10th Sep '25

Multiple Choice 2015-16

Question	Answer	Point
What are the three states of matter?	The three states of matter are solid, liquid and gas.	The three states of matter are solid, liquid and gas. Melting and freezing take place at the melting point, boiling and condensing take place at the boiling point.
How are the three states of nmatter represented when using solid spheres to represent particles?	When using solid spheres to represent particles, the three states of matter can be represented as follows: Solid - particles packed tightly together and are arranged in a regular pattern. Liquid - particles are close together and arranged in a random way. Gas - particles are far apart and arranged in a random way.	The three states of matter can be represented by a simple model. In this model, particles are represented by small solid spheres.
What happens to a substance as it changes from a solid to a liquid?	When a substance is changing state from a solid to a liquid, it is melting. In a solid the particles are close together and touching in a fixed pattern. They are vibrating around a fixed point. As the particles are heated they begin to store more internal energy. The particles transfer this internal energy store using a thermal pathway into kinetic energy and therefore move more. In a liquid the particles are still touching but are arranged in a random way and can flow over one another.	Particle theory can help to explain melting, boiling, freezing and condensing.
Why do different substances have different melting and boiling points?	Different substances have different melting and boiling points because the amount of energy needed to change state from solid to liquid and from liquid to gas depends on the strength of the forces between the particles of the substance. The nature of the particles involved depends on the type of bonding and the structure of the substance. The stronger the forces between the particles the higher the melting point and boiling point of the substance.	The amount of energy needed to change state from solid to liquid and from liquid to gas depends on the strength of the forces between the particles of the substance. The nature of the particles involved depends on the type of bonding and the structure of the substance. The stronger the forces between the particles the higher the melting point and boiling point of the substance.
What are the limitations to using simple particle models used to represent the different states of matter?	The limitations of the simple particle models used to represent the different states of matter are that in the model there are no forces represented, all particles are represented as spheres and that the spheres are solid.	(HT only) Limitations of the simple model above include that in the model there are no forces, that all particles are represented as spheres and that the spheres are solid.
What state would substance A be at room temperature (25oC) when substance A has a melting point of -10oC and a boiling point of 55oC?	When substance A has a melting point of -10oC and a boiling point of 55oC, substance A would be a liquid at room temperature as 25oC is greater than the melting point of substance A but lower than its boiling point.	Students should be able to predict the states of substances at different temperatures given appropriate data
Why does water boil at 100oC rather than 90oC, in terms of bonding and energy transfers?	Water boils at 100oC, rather than 90oC, as the amount of energy needed to break each bond between the water molecules is only reached at 100oC and not at 90oC.	Students should be able to explain the different temperatures at which changes of state occur in terms of energy transfers and types of bonding
(HT) What are the limitations of the particle theory in relation to changes of state?	(HT) The limitations of particle theory in relation to changes of state are that the particles are represented by solid, inelastic spheres which have no forces between them. It also does not show the bonds between molecules, does not take into account the size of particles and the space between them.	(HT only) explain the limitations of the particle theory in relation to changes of state when particles are represented by solid inelastic spheres which have no forces between them.
What is the smallest part of an element that can exist?	An atom is the smallest part of an element that can exist.	All substances are made of atoms. An atom is the smallest part of an element that can exist.
How are atoms of elements represented on the periodic table?	Atoms of each element are represented by a chemical symbol.	Atoms of each element are represented by a chemical symbol, eg O represents an atom of oxygen, Na represents an atom of sodium.
How many different elements are there?	There are over 100 different elements.	There are about 100 different elements. Elements are shown in the periodic table.
How are compounds formed?	Compounds are formed from elements by chemical reactions.	Compounds are formed from elements by chemical reactions.
How can chemical reactions be detected other than through the observation of new substances forming?	Chemical reactions can be measured by a detectable energy change.	Chemical reactions always involve the formation of one or more new substances, and often involve a detectable energy change.
What is a compound and how is it respresented?	Compounds contain two or more elements chemically combined in fixed proportions and can be represented by formulae using the symbols of the atoms from which they were formed.	Compounds contain two or more elements chemically combined in fixed proportions and can be represented by formulae using the symbols of the atoms from which they were formed.
What type of reaction is needed to separate a compound into elements?	Compounds can only be separated into elements by chemical reactions.	Compounds can only be separated into elements by chemical reactions.
How are chemical reactions represented?	Chemical reactions can be represented by word equations or equations using symbols and formulae.	Chemical reactions can be represented by word equations or equations using symbols and formulae.
What are the names and symbols of elements in Groups 1 and 7?	Group 1: L (Lithium), Na (Sodium), K (Potassium), Rb (Rubidium), Cs (Caesium), Fr (Francium). Group 7: F (Fluorine), Neon (Ne), Argon (Ar), Kr (Krypton), Xe (Xenon), Rn (Radon).	Students will be supplied with a periodic table for the exam and should be able to use the names and symbols of the first 20 elements in the periodic table, the elements in Groups 1 and 7, and other elements in this specification
What are the names of the following compounds: NaCl, KF, LiBr?	NaCl - sodium chloride, KF - potassium fluoride, LiBr - Lithium bromide.	Name compounds of these elements from given formulae or symbol equations.
In a chemical equation, what do the symbols (s), (l), (g), and (aq) represent?	In a chemical equation, the following symbols represent the following states: (s) = Solid (l) = Liquid (g) = Gas (aq) = Aqueous solution (dissolved in water)	In chemical equations, the three states of matter are shown as (s), (l) and (g), with (aq) for aqueous solutions.
What state symbols are added to each part of the chemical equation below? C O2 -> CO2	The state symbols added the each part of the chemical equation is seen below: C (s) O2 (g) -> CO2 (g)	Review from KS3 balancing equations if secure in the naming and symbols of basic elements and compounds.
What is a mixture?	A mixture consists of two or more elements or compounds not chemically combined together.	A mixture consists of two or more elements or compounds not chemically combined together.
What happens to the chemical properties of each substance in a mixture?	In a mixture the chemical properties of each substance in the mixture are unchanged.	The chemical properties of each substance in the mixture are unchanged.
When mixtures are separated by physical processes how does this affect the chemical reactions and substances made?	Mixtures separated by physical processes do not involve chemical reactions and no new substances are made.	Mixtures can be separated by physical processes such as filtration, crystallisation, simple distillation, fractional distillation and chromatography. These physical processes do not involve chemical reactions and no new substances are made.
How are mixtures separated using filtration?	Mixtures of insoluble solid molcules and liquids can be seperated using filitration. The insoluble solid is unable to pass through filter paper allowing them to be separated from a liquid. For example a when a mixture of sand and water is filtered the sand remains in the filter and the water passes through.	Filtration (review from KS3)
How are mixtures separated using crystallisation?	Crystallisation can be used to separate a solid that has dissolved in a liquid. The mixture is heated to remove most of the liquid and then left to allow crystals of the solid to form	Crystallisation (review from KS3)
How are mixtures separated using simple distillation?	Distillation is a process that can be used to separate a pure liquid from a mixture of liquids. It works when the liquids have different boiling points. Distillation is commonly used to separate ethanol - the alcohol in alcoholic drinks - from water.	Simple distillation (review from KS3)
How are mixtures separated using fractional distillation?	During fractional distillation a mixture is separated into its component parts, or fractions, based on their boiling point. This is achieved by heating them to a temperature at which one or more fractions of the compound will vaporise and condensing them at different temperatures in a distillation column.	fractional distillation
How are mixtures separated using chromatography?	In chromatography a mixture is passed through a medium in which the components move at different rates allowing separation of the individual components.	chromatography (review from KS3)
How could we separare a mixture of sand, salt, iron and water into its individual components?	A mixture of sand, salt, iron and water can be seperated using filtration to separate out the insoluble solids (iron and sand) from the solution (salt and water). Iron can be separated from the sand using a magnet. Salt and water can be separated by either evaporation or distillation.	Students should be able to suggest suitable separation and purification techniques for mixtures when given appropriate information.
What can lead to a scientific model being changed or replace?	New experimental evidence may lead to a scientific model being changed or replaced.	New experimental evidence may lead to a scientific model being changed or replaced. (WS) This historical context provides an opportunity for students to show an understanding of why and describe how scientific methods and theories develop over time.
What is an atom?	The word atom means indivisible. An atom is the smallest constituent unit of ordinary matter.	Before the discovery of the electron, atoms were thought to be tiny spheres that could not be divided.
What were the main features of the 'plum pudding' model of the atom?	In the plum pudding model the atom was thought to be a sphere of positive charge with negatively charged electrons dotted around inside it like plums in a pudding.	The discovery of the electron led to the plum pudding model of the atom.
How did the 'plum pudding' model describe the structure of an atom?	The plum pudding model suggested that the atom is a ball of positive charge with negative electrons embedded in it.	The plum pudding model suggested that the atom is a ball of positive charge with negative electrons embedded in it.
How did the Rutherford's alpha particle scattering experiment change our understanding of the structure of the atom?	A beam of alpha particles was aimed at very thin gold foil and their passage through the foil detected. The scientists expected the alpha particles to pass straight through the foil, but something else also happened. Some of the alpha particles emerged from the foil at different angles, and some even came straight back. The scientists realised that the positively charged alpha particles were being repelled and deflected by a tiny concentration of positive charge in the atom. As a result of this experiment, the plum pudding model was replaced by the nuclear model of the atom.	The results from the alpha particle scattering experiment led to the conclusion that the mass of an atom was concentrated at the centre (nucleus) and that the nucleus was charged. This nuclear model replaced the plum pudding model.
What contribution did Niels-Bohr make in furthering our understanding of the structure of the atom.	Niels-Bohr adapted the nuclear model by suggesting that electrons orbit the nucleus at specific distances. The theoretical calculations of Bohr agreed with experimental observations.	Niels Bohr adapted the nuclear model by suggesting that electrons orbit the nucleus at specific distances. The theoretical calculations of Bohr agreed with experimental observations.
Which subatomic particle gives the nucleus of the atom a positive charge?	Protons give the nucleus of the atom a postive charge, each proton has mass of 1 and a 1 charge.	Later experiments led to the idea that the positive charge of any nucleus could be subdivided into a whole number of smaller particles, each particle having the same amount of positive charge. The name proton was given to these particles.
What discovery did James Chadwick make that advanced our understanding of the structure of an atom?	James Chadwick provided evidence that the nucleus of an atom was also made of neutrons. Protons were discovered some 20 years prior.	The experimental work of James Chadwick provided the evidence to show the existence of neutrons within the nucleus. This was about 20 years after the nucleus became an accepted scientific idea.
How did the evidence of alpha particles scattering lead to a change in the atomic model?	The new evidence of alpha particles scattering during the gold leaf experiment lead to a new atomic model as it proved most of the atom was empty space except for a postive charge at the very centre of it.	Students should be able to describe why the new evidence from the scattering experiment led to a change in the atomic model
Describe the currently accepted structure of the atom	A nucleus composed of protons and neutrons, surrounded by shells of electrons.	Students should be able to describe the difference between the plum pudding model of the atom and the nuclear model of the atom.
What are the relative electrical charges of each sub-atomic particle?	The relative electrical charges of each sub-atomic particles are: Proton 1 Neutron 0 Electron -1	The relative electrical charges of the particles in atoms are: Proton +1 Neutron 0 Electron -1
Why do atoms have no overall charge?	Atoms do not have an overall charge as a number of POSITIVE protons will always match the number of NEGATIVE electrons.	Atoms have no overall electrical charge.
If an atom has 9 protons, how many electrons would it have?	If an atom has 9 protons it would have 9 electrons.	In an atom, the number of electrons is equal to the number of protons in the nucleus.
What does the atomic number of an element tell us?	The atomic number tells us the number of protons found in an atom of that element.	The number of protons in an atom of an element is its atomic number.
What do all atoms of a particular element have in common?	Atoms of the same element all have the same number of protons.	All atoms of a particular element have the same number of protons.
What are the differences between an atom of Nitrogen and an atom of Carbon. What is it that makes them unique elements?	An atom of carbon has: Protons= 6 Electrons= 6 Neutrons= 6. An atom of Nitrogen has: Protons= 7 Electrons= 7 Neutrons= 7. It is the differing number of protons which makes them unique elements.	Atoms of different elements have different numbers of protons.
How does the current nuclear model describe an atom?	The nuclear model shows that an atom is made of a small nucleus of positive protons and neutral neutrons, it also has negatively charged electrons orbiting it in energy levels.	Students should be able to use the nuclear model to describe atoms.
How large is the radius of the nucleus of an atom in comparison to its total radius?	The radius of the nucleus of an atom compared to the total atoms radius is 1/10 000 of that of the atom (about 1 x 10 to the power -14 m).	The radius of a nucleus is less than 1/10 000 of that of the atom (about 1 x 10-14 m).
Where is the majority of the mass of the atom found?	The majority of the mass of the atom is found within the nucleus and is made up of protons and neutrons. Electrons have a negligible mass.	Almost all of the mass of an atom is in the nucleus.
What are the relative masses of each subatomic particle (proton, neutron and electron)?	The relative masses of the subatomic particles are: Proton = 1 Neutron = 1 Electron = negligible (very small)	The relative masses of protons, neutrons and electrons are: Proton 1 Neutron 1 Electron Very small
What does the mass number of an atom tell us about that atom?	The mass number tells us the total number of protons and neutrons within that atom.	The sum of the protons and neutrons in an atom is its mass number.
What is an isotope?	An isotope is an atom of the same element with differing numbers of neutrons.	Atoms of the same element can have different numbers of neutrons; these atoms are called isotopes of that element.
What do the individual tiles of the periodic table tell us?	The individual tiles of the periodic table tell us the chemical symbol, Mass number, Atomic (Proton) number	Atoms can be represented as shown in this example: (periodic table tile for sodium with mass and atomic number)
Calculate the number of protons, neutrons and electrons in an atom of Cobalt. Mass number = 59 and Atomic number = 27	The total number of subatomic particles in cobalk are: Protons: 27 Electrons: 27 Neutrons: 32	Students should be able to calculate the numbers of protons, neutrons and electrons in an atom or ion, given its atomic number and mass number.
How large are atoms? a) 1 × 10-6 m b) 1 × 10-8 m c) 1 × 10-10 m	The size of atoms are 1 × 10-10 m	Students should be able to relate size and scale of atoms to objects in the physical world.
Why does chlorine have a mass number of 35.5?	The relative atomic mass of an element is an average value that takes account of the abundance of the isotopes of the element. Chlorine exists as 75% Cl35 and 25% Cl37, an average of this is taken.	The relative atomic mass of an element is an average value that takes account of the abundance of the isotopes of the element.
What is the relative atomic mass of bromine where there are two isotopes of Bromine, 50% Br-79 and 50% Br-81?	The relative atomic mass of bromine is 80, since (79 x 50) + (81 x 50) / 100 = 80.	Students should be able to calculate the relative atomic mass of an element given the percentage abundance of its isotopes.
What is the maximum number of electrons that can be held by each of the three inner most shells?	The maximum number of electrons are 2 in the inner most shell, 8 in the second shell and 8 in the third shell.	The electrons in an atom occupy the lowest available energy levels (innermost available shells).
What would a diagram of the electron structure of an atom of carbon look like?	A diagram of the electronic structure of carbon would have 2 electrons on inner most shell, 4 on the second shell.	The electronic structure of an atom can be represented by numbers or by a diagram. For example, the electronic structure of sodium is 2,8,1 or (electron arrangement using dot-and-cross diagram) showing two electrons in the lowest energy level, eight in the second energy level and one in the third energy level.
Why is carbon found in group 4 of the periodic table?	Carbon is found in group 4 because there are 4 electrons in its outermost shell.	(WS) Students should be able to represent the electronic structures of the first twenty elements of the periodic table in both forms.
How big is the total radius of an average atom?	The total radius of an average atom is 0.1 nm (1 x 10-10 m).	Atoms are very small, having a radius of about 0.1 nm (1 x 10-10 m).
How are elements ordered in the periodic table?	The elements in the periodic table are arranged in order of atomic (proton) number and so that elements with similar properties are in columns, known as groups. The table is called a periodic table because similar properties occur at regular intervals.	The elements in the periodic table are arranged in order of atomic (proton) number and so that elements with similar properties are in columns, known as groups. The table is called a periodic table because similar properties occur at regular intervals.
Metals react to form __________ charged ions	Metals react to form POSITIVELY charged ions	Elements that react to form positive ions are metals.
In terms of electron structure, how are elements in the same group similar?	Elements in the same group in the periodic table have the same number of electrons in their outer shell (outer electrons) and this gives them similar chemical properties.	Elements in the same group in the periodic table have the same number of electrons in their outer shell (outer electrons) and this gives them similar chemical properties.
Non-metals react to form __________ charged ions	Non-metals react to form NEGATIVELY charged ions	Elements that do not form positive ions are non-metals.
What does the group and period of an element tell us about its electron structure?	Period = Total number of electron shells. Group = Total number of electrons found in the outermost shell	Students should be able to explain how the position of an element in the periodic table is related to the arrangement of electrons in its atoms and hence to its atomic number
Are there more metals or non-metal elements on the periodic table?	The majority of elements are metals.	The majority of elements are metals.
Predict how the reactivity of caesium would compare to lithium	Caesium would be far more reactive than lithium because it is further down group 1 so it experiences more shielding from the nucleus	Students should be able to predict possible reactions and probable reactivity of elements from their positions in the periodic table.
How were elements in early periodic tables ordered?	By atomic mass	Before the discovery of protons, neutrons and electrons, scientists attempted to classify the elements by arranging them in order of their atomic weights.
Why were early attempts at ordering the periodic table by atomic mass unsuccessful?	As this caused certain elements to be incorrectly placed in groups with elements with very different propertiesno.	The early periodic tables were incomplete and some elements were placed in inappropriate groups if the strict order of atomic weights was followed.
How did Mendeleev predict the existence of several undiscovered elements when designing his periodic table?	He identified where there was no existing element that fit the pattern of his periodic table, so left gaps in for them.	Mendeleev overcame some of the problems by leaving gaps for elements that he thought had not been discovered and in some places changed the order based on atomic weights.
How are metals and non-metal elements arranged on the periodic table	Metals are found to the left and towards the bottom of the periodic table. Non-metals are found towards the right and top of the periodic table.	Metals are found to the left and towards the bottom of the periodic table. Non-metals are found towards the right and top of the periodic table.
What steps were involved in the development of the periodic table?	1. Groups of three elements with similar properties called triads. 2. More accurate atomic weights 3. Newlands table in atomic weight (law of octaves) 4. Mendeleev who left gaps putting them in groups with similar properties	Students should be able to describe these steps in the development of the periodic table.
Which group of the periodic table are also named the nobel gases?	Group 0	The elements in Group 0 of the periodic table are called the noble gases.
Describe in terms of electron structure as to why all of the nobel gases are unreactive	They all have a full outer shell of electrons, as a result do not easily form molecules	The elements in Group 0 of the periodic table are unreactive and do not easily form molecules because their atoms have stable arrangements of electrons.
What is the same about the electron structure for all elements in Group 0 (noble gases)?	All elements in Group 0 (noble gases) have a full outer shell of electrons.	The noble gases have eight electrons in their outer shell, except for helium, which has only two electrons.
Describe the trend in boiling point down group 0	Boiling points increase with relative atomic mass (as you go down the group)	The boiling points of the noble gases increase with increasing relative atomic mass (going down the group).
What is the common name given to the group 1 elements?	Alkali metals	The elements in Group 1 of the periodic table are known as the alkali metals and have characteristic properties because of the single electron in their outer shell.
Give 4 common properties of transition metal elements.	Heat conductor, Electrical conductor, Lustrous (shiny), Dense, High melting and boiling point, High tensile strength, Strong, Hard	Students should be able to explain the differences between metals and non-metals on the basis of their characteristic physical and chemical properties. This links to Group 0, Group 1, Group 7 and Bonding, structure and the properties of matter
Write a word equation for the reaction of sodium with chlorine.	Sodium + Chlorine -> Sodium Chloride	Students should be able to describe the reactions of the first three alkali metals with oxygen, chlorine and water.
Describe the trend in reactivity in group 1 as you go down the group	Reactivity of elements in group 1 increases as you go down the group (Lithium = least reactive, Francium = most reactive)	In Group 1, the reactivity of the elements increases going down the group.
For elements in Group 1, what do the properties depend on?	Properties of the elements in Group 1 depend on the outer shell of electrons of the atoms	Students should be able to explain how properties of the elements in Group 1 depend on the outer shell of electrons of the atoms
Explain why elements become more reactive the further you go down group 1	Elements in group 1 react by giving up their outermost electron. The further down the group you go the weaker the attraction between the nucleus of the atom and the outermost electron, as well as a greater amount of shielding. Therefore the electron is given up more easily.	Students should be able to predict properties from given trends down the group.
What are the transition elements?	Metals with similar properties which are different from those of the elements in Group 1.	The transition elements are metals with similar properties which are different from those of the elements in Group 1.
Compare the properties of transition metal elements with those of the group 1 elements.	Group 1 metals are soft, highly reactive to oxygen and water, form alkali solutions, are less dense than group 2 metals. Group 2 metals are harder, less reactive.	Students should be able to describe the difference compared with Group 1 in melting points, densities, strength, hardness and reactivity with oxygen, water and halogens.
Give examples of 3 transition metals	Any three from the transition block eg. Cr, Mn, Fe, Co, Ni, Cu.	Students should be able to exemplify these general properties by reference to Cr, Mn, Fe, Co, Ni, Cu.
What is the common name given to the group 7 elements?	The halogens	The elements in Group 7 of the periodic table are known as the halogens and have similar reactions because they all have seven electrons in their outer shell.
Describe the trend in boiling point and melting point of elements as you go down group 7?	As you go down group 7, the melting and boiling points of the elements increases.	In Group 7, the further down the group an element is the higher its relative molecular mass, melting point and boiling point.
Describe the trend in reactivity of elements as you go down group 7?	As you go down group 7, the reactivity of the elements decreases.	In Group 7, the reactivity of the elements decreases going down the group.
Write a word equation for the reaction between sodium chloride and fluorine. What type of reaction is this?	Sodium chloride Fluorine -> Sodium Fluoride Chlorine. This is a displacement reaction as the more reactive halogen displaces the less reactive halogen from its compound.	A more reactive halogen can displace a less reactive halogen from an aqueous solution of its salt.
In terms of electron structure, whAt do all group 7 elements share in common?	They all have 7 electrons in their outermost shell	Students should be able to explain how properties of the elements in Group 7 depend on the outer shell of electrons of the atoms
List the elements of group 7 in order of reactivity.	Fluorine, Chlorine, Bromine, Iodine, Astatine	Students should be able to predict properties from given trends down the group.
Many transition elements are also useful as catalysts. What is a catalyst?	A catalyst is a substance which speeds up a chemical reaction without being used up itself.	Many transition elements have ions with different charges, form coloured compounds and are useful as catalysts.
List the general properties of compounds of transition elements		Students should be able to exemplify these general properties by reference to compounds of Cr, Mn, Fe, Co, Ni, Cu.
How can different atoms interact with each to gain a full outer shell of electrons.	Atoms can gain, lose or share electrons. (Metals on their own will delocalise their outer electron(s).)	There are three types of strong chemical bonds: ionic, covalent and metallic. ALTERNATIVE activity - independent thinking.
What are the three types of chemical bonding?	Ionic, Metallic and Covalent	There are three types of strong chemical bonds: ionic, covalent and metallic.
Name the type of attraction between particles in an ionic bond	Electrostatic attraction (attraction between oppositely charged particles)	For ionic bonding the particles are oppositely charged ions.
In terms of electrons, how are covalent bonds formed?	When two non-metal atoms share electrons to form a bond	For covalent bonding the particles are atoms which share pairs of electrons.
Metallic bonds have delocalised electrons. What are delocalised electrons?	Electrons in a molecule, ion or solid metal that are not associated with a single atom	For metallic bonding the particles are atoms which share delocalised electrons.
Ionic bonding occurs in compounds formed from ________ combined with ___________.	Ionic bonding occurs in compounds formed from METALS combined with NON-METALS.	Ionic bonding occurs in compounds formed from metals combined with non-metals.
Covalent bonding occurs when _____________ atoms bond together.	Covalent bonding occurs when NON-METAL atoms bond together.	Covalent bonding occurs in most non-metallic elements and in compounds of non-metals.
Metallic bonding occurs between atoms of __________ elements.	Metallic bonding occurs between atoms of METAL elements.	Metallic bonding occurs in metallic elements and alloys.
What is chemical bonding?	chemical bonding is where atoms are held together because of electrostatic forces caused by the transfer or sharing of electrons.	Students should be able to explain chemical bonding in terms of electrostatic forces and the transfer or sharing of electrons.
Describe the transfer of electrons in an ionic bond	Electrons are donated from the metal element in order to complete the outer shell of the non-metal element	When a metal atom reacts with a non-metal atom, electrons in the outer shell of the metal atom are transferred.
When a metal atom become an ion it loses electrons. How does this effect its charge?	It becomes a positively charged ion.	Metal atoms lose electrons to become positively charged ions.
When a non-metal atom bonds ionically it gains electrons. How does this effect its charge?	It becomes a negatively charged ion.	Non-metal atoms gain electrons to become negatively charged ions.
What is the electronic structure of ions produced by group 1,2 metals and group 6,7 non metals?	They have full outside shells of electrons giving them a stable electronic configuration, the same as a noble gas.	The ions produced by metals in Groups 1 and 2 and by non-metals in Groups 6 and 7 have the electronic structure of a noble gas (Group 0).
How could you show the formation of an ionic compound using a dot and cross diagram?	Showing outer electrons only. Crosses for one element and dots for the other. Show transfer of electrons on shell. Use brackets to show the overall charge of the ions formed.	The electron transfer during the formation of an ionic compound can be represented by a dot and cross diagram. E.g. for sodium chloride.
Draw a dot cross diagram to show the ionic bond in sodium chloride.	Diagram: Sodium - Electron strucuture represented in square brackets, with a 1 charge on the top right outside the bracket. . It's one outer shell electron removed. Chlorine - Electron strucuture represented in square brackets, with a -1 charge on the top right outside the bracket. One extra electron represented as either a dot or cross shown to represent the electron gained from sodium.	Students should be able to draw dot and cross diagrams for ionic compounds formed by metals in Groups 1 and 2 with non-metals in Groups 6 and 7.
What charge do ions of elements from the following groups form 1) Group 1 2) Group 2 3) Group 6 4) Group 7	1) Group 1 = +1 ion 2) Group 2 = +2 ion 3) Group 6 = -2 ion 4) Group 7 = -1 ion	The charge on the ions produced by metals in Groups 1 and 2 and by non-metals in Groups 6 and 7 relates to the group number of the element in the periodic table.
Explain why potassium chloride is KCl but potassium oxide is K2O	The overall charge of an ionic compound will always be neutral. Potassium forms an ion with a 1 charge, so will bond in a 1:1 ratio chlorine as chlorine forms a -1 ion. Oxygen on the other hand forms a -2 ion, so for each Oxygen 2 potassiums would be needed to neutralise the charge.	Students should be able to work out the charge on the ions of metals and non-metals from the group number of the element, limited to the metals in Groups 1 and 2, and non-metals in Groups 6 and 7.
What is an ionic compound?	A giant structure of ions	An ionic compound is a giant structure of ions.
What do we call the attraction between oppositely charged ions?	Electrostatic attraction	Ionic compounds are held together by strong electrostatic forces of attraction between oppositely charged ions.
Describe the structure of a giant ionic lattice.	It is a 'lattice' because the arrangement is a regular one and 'giant' because the arrangement is repeated many times with large numbers of ions.	These forces act in all directions in the lattice: this is called ionic bonding.
What two models can be used to represent giant ionic structures?	Ball and stick and charged ion ionic lattice	The structure of sodium chloride can be represented in the following forms: ball and stick giant lattice and charged ion ionic lattice.
Give a limitation of each the ball and stick model and charged ion ionic lattice models for representing ionic bonds.	Ball and stick model: - The ions are actually packed closer together - Gives a false image of bond direction when is only electrostatic attraction Charged ion ionic lattice model: - Difficult to see the arrangement of ions in 3D.	Students should be able to describe the limitations of using dot and cross, ball and stick, two and three-dimensional diagrams to represent a giant ionic structure.
Determine the empirical formulae of a compound given the ions: a) Na+ and N3- b) Al3+ and O2-	a) Na3N b) Al2O3	Students should be able to work out the empirical formula of an ionic compound from a given model or diagram that shows the ions in the structure.
Draw out a dot cross diagram to show the ionic bond formed in the compound sodium chloride.	The sodium ion has an electon pattern of (2,8) and is represented in square brackets with a + charge in the top right corner, as a consequence of having lost an electron from its outer shell. This is then placed next to the chloride ion, which has an electron pattern of (2,8,8) and is also represented in square bracket, but with a - charge in the top right corner, due to it gaining an electron.	Students should be familiar with the structure of sodium chloride but do not need to know the structures of other ionic compounds.
What are covalent bonds?	Strong bonds that form when atoms share pairs of electrons	When atoms share pairs of electrons, they form covalent bonds. These bonds between atoms are strong.
What type of substances have covalent bonds?	small molecules	Covalently bonded substances may consist of small molecules.
What are the names of the following substances CO2 H2O H2 Cl2	Carbon dioxide water hydrogen chlroine	Students should be able to recognise common substances that consist of small molecules from their chemical formula.
Give an example of large molecules with covalent bonds	Polymers	Some covalently bonded substances have very large molecules, such as polymers.
Give two examples of substances that have giant covalent structures	diamond graphite silicon dioxide	Some covalently bonded substances have giant covalent structures, such as diamond and silicon dioxide.
List three ways to represent covalent bonds in molecules	dot and cross diagrams ball and stick diagrams display formula	The covalent bonds in molecules and giant structures can be represented in the following forms: using dot-and-cross diagram, ball-and-stick diagram or displayed formula)
How are polymers commonly represented?	Polymers can be represented using displayed formulae, where n is a large number.	Polymers can be represented using displayed formulae, where n is a large number.
Draw dot and cross diagrams for the molecules of hydrogen, chlorine, oxygen, nitrogen, hydrogen chloride, water, ammonia and methane look like?		Students should be able to draw dot and cross diagrams for the molecules of hydrogen, chlorine, oxygen, nitrogen, hydrogen chloride, water, ammonia and methane
How would you draw a single covalent bond?	single line between atoms	Students should be able to represent the covalent bonds in small molecules, in the repeating units of polymers and in part of giant covalent structures, using a line to represent a single bond
What are the limitations of using dot and cross, ball and stick, 2D and 3D diagrams to represent substances?	dot and cross, ball and stick do not show orginatation in space.	Students should be able to describe the limitations of using dot and cross, ball and stick, two and three-dimensional diagrams to represent molecules or giant structures
What is the structure of a metal like?	Metals consist of giant structures of atoms arranged in a regular pattern.	Metals consist of giant structures of atoms arranged in a regular pattern.
How are the electrons in the outer shell of metal atoms arranged?	The electrons in the outer shell of metal atoms are delocalised and so are free to move through the whole structure.	The electrons in the outer shell of metal atoms are delocalised and so are free to move through the whole structure.
Why are metallic bonds so strong?	The sharing of delocalised electrons gives rise to strong metallic bonds. The bonding in metals may be represented in the following form: (diagram)	The sharing of delocalised electrons gives rise to strong metallic bonds. The bonding in metals may be represented in the following form: (diagram)
Describe the structure of metallic bonding?	positive atoms surrounded by negatively charged delocalised electrons	Students should be able to recognise substances as metallic giant structures from diagrams showing their bonding.
When compared with the properties of materials, do atoms have the same bulk properties?	Atoms themselves do not have the bulk properties of materials.	Students should be able to recognise that atoms themselves do not have the bulk properties of materials
1. How do a metal and non-metal bond? 2. How do two non-metals bond?	1. ionic bonding by losing/gaining electrons. 2. covalent bonding by sharing pairs of electrons.	Students should be able to describe and explain the bonding in ionic and simple covalent bonding.
Why are metals good conductors of electricity?	Metals are good conductors of electricity because the delocalised electrons in the metal carry electrical charge through the metal.	Metals are good conductors of electricity because the delocalised electrons in the metal carry electrical charge through the metal.
In pure metals atoms are arranged in layers. What property does this give them?	It causes them to be malleable (means they can be bent and shaped).	In pure metals, atoms are arranged in layers, which allows metals to be bent and shaped.
Why are metals good conductors of thermal energy?	Metals are good conductors of thermal energy because energy is transferred by the delocalised electrons.	Metals are good conductors of thermal energy because energy is transferred by the delocalised electrons.
Why are pure metals often mixed with other metals or carbon?	Pure metals are too soft for many uses and so are mixed with other metals to make alloys which are harder.	Pure metals are too soft for many uses and so are mixed with other metals to make alloys which are harder.
Why are alloys harder than pure metals?	Alloys are harder than pure metals as alloys contain atoms of different sizes. This causes distortion of the layers of atoms compared with the regular struccture of a pure metal. The regular structure in a pure metal allows the layers to slide over one another.	Students should be able to explain why alloys are harder than pure metals in terms of distortion of the layers of atoms in the structure of a pure metal.
Describe the structure of an ionic compound?	Ionic compounds have regular structures (giant ionic lattices) in which there are strong electrostatic forces of attraction in all directions between oppositely charged ions.	Ionic compounds have regular structures (giant ionic lattices) in which there are strong electrostatic forces of attraction in all directions between oppositely charged ions.
Explain why ionic compounds have high melting and boiling points?	These compounds have high melting points and high boiling points because of the large amounts of energy needed to break the many strong bonds.	These compounds have high melting points and high boiling points because of the large amounts of energy needed to break the many strong bonds.
Under what conditions are ionic compounds able to conduct electricity?	When melted or dissolved in water, ionic compounds conduct electricity because the ions are free to move and so charge can flow.	When melted or dissolved in water, ionic compounds conduct electricity because the ions are free to move and so charge can flow.
What are the structures of different ionic compounds?	Need to know the structure of sodium chloride.	Knowledge of the structures of specific ionic compounds other than sodium chloride is not required.
Substances that consist of small molecules are most commonly which states of matter at room temperature?	They tend to have lower boiling points, meaning they commonly exist at room temperature either as gases or liquids.	Substances that consist of small molecules are usually gases or liquids that have relatively low melting points and boiling points.
How does the size of a molecule affect the size of its intermolecular force?	The larger the molecule the greater the size of its intermolecular force. Hence larger molecules tend to have higher melting and boiling points.	The intermolecular forces increase with the size of the molecules, so larger molecules have higher melting and boiling points.
Explain why substances that consist of small molecules often have low boiling and melting points	Smaller molecules tend to have weaker intermolecular forces of attraction. This means only small amounts of energy are required to overcome the intermolecular forces that hold molecules of that substance together.	These substances have only weak forces between the molecules (intermolecular forces).
Why are covalent compounds unable to conduct electricity?	Because covalent molecules carry no overall charge	These substances do not conduct electricity because the molecules do not have an overall electric charge.
What is the difference between intermolecular forces and intramolecular forces?	Intermolecular forces are the forces of attraction between different molecules of the same substance. Intramolecular forces are the bonds between atoms of the same molecule eg. ionic or covalent bonds.	It is these intermolecular forces that are overcome, not the covalent bonds, when the substance melts or boils.
Which is stronger: A covalent bond or intermolecular force?	Intermolecular forces are weak when compared with covalent bonds and explain the bulk properties of molecular substances.	Students should be able to use the idea that intermolecular forces are weak compared with covalent bonds to explain the bulk properties of molecular substances.
Why is diamond so hard, in terms of its structure and bonding?	each carbon atom forms four covalent bonds with other carbon atoms in a giant covalent structure, so diamond is very hard, has a very high melting point and does not conduct electricity.	Students should be able to explain the properties of diamond in terms of its structure and bonding.
Why do metals tend to have high melting and boiling points?	Metals have giant structures of atoms with strong metallic bonding. This means that most metals have high melting and boiling points.	Metals have giant structures of atoms with strong metallic bonding. This means that most metals have high melting and boiling points.
How many bonds does each carbon atom form in graphite and how does this impact it's structure?	In graphite, each carbon atom forms three covalent bonds with three other carbon atoms, forming layers of hexagonal rings which have no covalent bonds between the layers.	In graphite, each carbon atom forms three covalent bonds with three other carbon atoms, forming layers of hexagonal rings which have no covalent bonds between the layers.
What happens to the spare electron that remains unused in a covalent bond in graphite?	It becomes delocalised (shared between atoms)	In graphite, one electron from each carbon atom is delocalised.
Why do giant covalent structures have very high melting and boiling points?	Their covalent bonds must be overcome in order for them to melt or boil, meaning large amounts of energy are required..	These bonds must be overcome to melt or boil these substances.
Why is graphite soft and slippery?	Because individual layer of graphite are only held together by weak intermolecular forces, allowing them to easily slide away from each other.	Students should be able to explain the properties of graphite in terms of its structure and bonding.
How is graphite similar to metals?	Graphite is similar to metals in that is has delocalised electrons.	Students should know that graphite is similar to metals in that it has delocalised electrons.
What makes graphene useful in electronics and composites?	Graphene is a single layer of graphite and has properties that make it useful in electronics and composites.	Graphene is a single layer of graphite and has properties that make it useful in electronics and composites.
What are the properties of carbon nanotubes and what do their properties make them useful for?	Carbon nanotubes are cylindrical fullerenes with very high length to diameter ratios. Their properties make them useful for nanotechnology, electronics and materials.	Carbon nanotubes are cylindrical fullerenes with very high length to diameter ratios. Their properties make them useful for nanotechnology, electronics and materials.
What are the properties of graphene in terms of its structure and bonding?	- One atom thick, so is 2D in structure. - Strong, as each layer of graphene is held together by strong covalent bonds. - Able to conduct electricity and heat, due to each carbon giving up a delocalised electron.	Students should be able to explain the properties of graphene in terms of its structure and bonding.
What are fullerenes and what is their structure?	Fullerenes are molecules of carbon atoms with hollow shapes. The structure of fullerenes is based on hexagonal rings of carbon atoms but they may also contain rings with five or seven carbon atoms.	Fullerenes are molecules of carbon atoms with hollow shapes. The structure of fullerenes is based on hexagonal rings of carbon atoms but they may also contain rings with five or seven carbon atoms.
Name three uses of fullerenes?	Fullerenes can be used as carbon nanotubes to reinforce graphite in tennis rackets, semiconductors in electrical circuits, and as nanotubes as a container from transporting a drug in the body.	Students should be able to give examples of the uses of fullerenes, including carbon nanotubes.
Diamond, graphite and fullerenes are all examples of what type of structure?	Diamond, graphite and fullerenes are all examples of giant covalent structures	Substances that consist of giant covalent structures are solids with very high melting points.
How many bonds can an individual atom of carbon form? How many bonds does each carbon form in an atom of a) Diamond b) Graphite	A single carbon atom can form a maximum of four possible bonds. a) In diamond each carbon atom is covalently bonded to 4 other carbon atoms. b) In graphite each carbon atom is covalently bonded to 3 other carbon atoms.	In diamond, each carbon atom forms four covalent bonds with other carbon atoms in a giant covalent structure, so diamond is very hard, has a very high melting point and does not conduct electricity.
Molecules of diamond, graphite and fullerenes are all held together by what type of bonds?	Covalent bonds	All of the atoms in these structures are linked to other atoms by strong covalent bonds.
Which giant covalent structures are made only from carbon?	Diamond and graphite (forms of carbon) and silicon dioxide (silica) are examples of giant covalent structures.	Diamond and graphite (forms of carbon) and silicon dioxide (silica) are examples of giant covalent structures.
What was the first fullerene to be discovered and what is its shape?	The first fullerene to be discovered was Buckminsterfullerene (C60) which has a spherical shape.	The first fullerene to be discovered was Buckminsterfullerene (C60) which has a spherical shape.
What sort of structures does nanoscience refer to?	Nanoscience refers to structures that are 1-100 nm in size, of the order of a few hundred atoms.	Nanoscience refers to structures that are 1?100 nm in size, of the order of a few hundred atoms.
What is the size of a fine particle and which is smaller, nanoparticles or fine particles?	Nanoparticles, are smaller than fine particles (PM2.5), which have diameters between 100 and 2500 nm (1 x 10-7 m and 2.5 x 10-6 m).	Nanoparticles, are smaller than fine particles (PM2.5), which have diameters between 100 and 2500 nm (1 x 10-7 m and 2.5 x 10-6 m).
What is the diameter of coarse particles, such as dust?	Coarse particles (PM10) have diameters between 1 x 10-5 m and 2.5 x 10-6 m. Coarse particles are often referred to as dust.	Coarse particles (PM10) have diameters between 1 x 10-5 m and 2.5 x 10-6 m. Coarse particles are often referred to as dust.
What happens to the size of the surface area to volume ratio of a cube is you decrease the size of the sides by a factor or 10?	As the side of cube decreases by a factor of 10 the surface area to volume ratio increases by a factor of 10.	As the side of cube decreases by a factor of 10 the surface area to volume ratio increases by a factor of 10.
Why are the properties of nanoparticles different from those for the same materials in bulk?	Nanoparticles may have properties different from those for the same materials in bulk because of their high surface area to volume ratio. It may also mean that smaller quantities are needed to be effective than for materials with normal particle sizes.	Nanoparticles may have properties different from those for the same materials in bulk because of their high surface area to volume ratio. It may also mean that smaller quantities are needed to be effective than for materials with normal particle sizes.
How do nanoparticles compare in size to individual atoms?	Nanoparticles are made of up to 1000 atoms or molecules, therefore their size is larger than that of an atom.	Students should be able to compare ?nano? dimensions to typical dimensions of atoms and molecules.
What are the main applications of nanoparticles?	Nanoparticles have many applications in medicine, in electronics, in cosmetics and sun creams, as deodorants, and as catalysts.	Nanoparticles have many applications in medicine, in electronics, in cosmetics and sun creams, as deodorants, and as catalysts. New applications for nanoparticulate materials are an important area of research.
What are the advantages and disadvantages of using nanoparticles?	The advantages of nanoparticles are endless as they link to many new technilogies both commercially and medically however there are disadvantages as well. There are some concerns that nanoparticles may be toxic to people. They may be able to enter the brain from the bloodstream and cause harm. Some people think more tests should take place before nanoparticles of a material are used on a wider scale.	Students should consider advantages and disadvantages of the applications of these nanoparticulate materials, but do not need to know specific examples or properties other than those specified.
What sort of molecules are polymers?	Polymers are very large molecules.	Polymers are very large molecules.
What two monomers form polyester?	ethane diol and hexanedioic acid polymerise to produce a polyester.	For example: ethane diol and hexanedioic acid polymerise to produce a polyester.
What type of bond links individual monomers together when forming a polymer?	The atoms in the polymer molecules are linked to other atoms by strong covalent bonds.	The atoms in the polymer molecules are linked to other atoms by strong covalent bonds.
What type of hydrocarbons are used to make polymers?	Alkenes can be used to make polymers such as poly(ethene) and poly(propene) by addition polymerisation.	Alkenes can be used to make polymers such as poly(ethene) and poly(propene) by addition polymerisation. Use models to represent addition polymerisation.
Why are polymers solids at room temperature?	The intermolecular forces between polymer molecules are relatively strong and so these substances are solids at room temperature.(Remember the greater the size of a molecule the greater the strength its intermolecular forces)	The intermolecular forces between polymer molecules are relatively strong and so these substances are solids at room temperature.
What happens in an addition polymerisation reaction?	In addition polymerisation reactions, many small molecules (monomers) join together to form very large molecules (polymers).	In addition polymerisation reactions, many small molecules (monomers) join together to form very large molecules (polymers).
How is a polymer of poly(ethene) produced from ethene? (Show using a diagram)	A polymer of poly(ethene) can be made by many monomers of ethene joining together to make a long chain of polymers. The diagram would show a C=C in the monomer but only a single bond in the polymer e.g. nCH2=CH2 --> [-CH2CH2-]n	For example (displayed formula showing ethene monomer becoming poly(ethene)).
(Chem only) How is the structure of the repeated unit of an addition polymer related to the monomer?	In addition polymers the repeating unit has the same atoms as the monomer because no other molecule is formed in the reaction.	In addition polymers the repeating unit has the same atoms as the monomer because no other molecule is formed in the reaction.
(Chem only) How can you identify if you have a polymer or a monomer structure?	addition polymers and monomers can be identified from diagrams by the presence of the functional group C=C in the monomers	Students should be able to recognise addition polymers and monomers from diagrams in the forms shown and from the presence of the functional group C=C in the monomers
(Chem only) What occurs during a condensation polymersiation reaction?	When monomers with two functional groups react they join together, usually losing small molecules such as water, and so the reactions are called condensation reactions.	When these types of monomers react they join together, usually losing small molecules such as water, and so the reactions are called condensation reactions. Use models to represent condensation polymerisation.
(Chem only) How many functional groups does each monomer have in the simplest condensation polymerisation reactions?	The simplest polymers are produced from two different monomers with two of the same functional groups on each monomer.	The simplest polymers are produced from two different monomers with two of the same functional groups on each monomer.
(Chem only) What are the basic principles of condensation polymersiation? (refer to functional groups and repeating units in your answer)	The basic principles of condensation polymerisation are that each monomer has two functional groups and the repeat units are made up of at least two different monomers in alternating sequence	Students should be able to explain the basic principles of condensation polymerisation by reference to the functional groups in the monomers and the repeating units in the polymers.
(Chem only) When does condensation polymerisation occur?	Condensation polymerisation involves monomers with two functional groups.	Condensation polymerisation involves monomers with two functional groups.
(Chem only) What are the monomers that form the following naturally occuring polymers? 1. proteins 2. starch 3. cellulose	(HT only) The monomers that form the naturally occuring polymers are: 1. proteins = amino acids 2. starch = glucose 3. cellulose = glucose	Students should be able to name the types of monomers from which these naturally occurring polymers are made. (HT only)
(Chem only) What type of polymerisation reaction occurs when amino acids react to form polypeptides? (Include a reason why)	(HT only) Amino acids react by condensation polymerisation to produce polypeptides, this is because amino acids have two different functional groups in one molecule.	Amino acids have two different functional groups in a molecule. Amino acids react by condensation polymerisation to produce polypeptides. (HT only)
(Chem only) What would the equation looks like for the polymerisation of glycine?	(HT only) n NCH COOH --> [-HNCH2COO-]n H2O.	For example: glycine is H NCH COOH and polymerises to produce the polypeptide (-HNCH2COO-) and n H2O. (HT only)
(Chem only) How are proteins an example of a condensation polymer?	(HT only) Proteins are an example of a condensation polymer because Different amino acids (with two functional groups) can be combined in the same chain to produce proteins.	Different amino acids can be combined in the same chain to produce proteins. (HT only)
(Chem only) What is DNA and what is its function?	(HT only) DNA (deoxyribonucleic acid) is a large molecule essential for life. DNA encodes genetic instructions for the development and functioning of living organisms and viruses.	DNA (deoxyribonucleic acid) is a large molecule essential for life. DNA encodes genetic instructions for the development and functioning of living organisms and viruses. (HT only)
(Chem only) Why is the structure of DNA described as a polymer?	(HT only) Most DNA molecules are two polymer chains, made from four different monomers called nucleotides, in the form of a double helix.	Most DNA molecules are two polymer chains, made from four different monomers called nucleotides, in the form of a double helix. (HT only)
(Chem only) What are the other naturally occuring polymers that are important for life processes?	(HT only) Other naturally occurring polymers important for life include proteins, starch and cellulose.	Other naturally occurring polymers important for life include proteins, starch and cellulose. (HT only)
What is the law of the conservation of mass?	The law of conservation of mass states that no atoms are lost or made during a chemical reaction so the mass of the products equals the mass of the reactants.	The law of conservation of mass states that no atoms are lost or made during a chemical reaction so the mass of the products equals the mass of the reactants.
Why must we ensure that chemical equations are balanced?	To accurately represent that no atoms are being made or lost during a chemical reaction, they are just converting from one form to another.	This means that chemical reactions can be represented by symbol equations which are balanced in terms of the numbers of atoms of each element involved on both sides of the equation.
What do the multipliers in normal script before a chemical formula represent? Eg 2MgO	The normal script numbers before a chemical formula represent you have that many of that particular atom or molecule. In the example 2MgO, the 2 represents that there are two molecules of MgO	Students should understand the use of the multipliers in equations in normal script before a formula and in subscript within a formula.
How do we calculate the relative formula mass (Mr) of a compound?	The relative formula mass (Mr) of a compound is the sum of the relative atomic masses of the atoms in the numbers shown in the formula.	The relative formula mass (Mr) of a compound is the sum of the relative atomic masses of the atoms in the numbers shown in the formula.
Why must the total relative formula mass of all of the reactants equal that of all of the products made?	The law of conservation of mass states that no atoms are lost or made during a chemical reaction so the mass of the products equals the mass of the reactants. Therefore the total atoms before and after a chemical reaction must be the same.	In a balanced chemical equation, the sum of the relative formula masses of the reactants in the quantities shown equals the sum of the relative formula masses of the products in the quantities shown.
When a gas is produced in a chemical reaction, why would the mass of the products appear to be less than that of the reactants?	The mass of the products will be reduced because the gas escapes into the surroundings. The total number of atoms will not have changed.	Some reactions may appear to involve a change in mass but this can usually be explained because a reactant or product is a gas and its mass has not been taken into account. For example: when a metal reacts with oxygen the mass of the oxide produced is greater than the mass of the metal or in thermal decompositions of metal carbonates carbon dioxide is produced and escapes into the atmosphere leaving the metal oxide as the only solid product.
Explain why in the reaction below the mass of the products would be greater than that of the reactants 2Mg (s) O2 (g) -> 2MgO (s)	Because oxygen gas would not be accounted for when the mass of the reactants are recorded, yet form part of the solid MgO produced. Therefore giving an increase in mass, but no new atoms were created or destroyed within the reaction.	Students should be able to explain any observed changes in mass in non-enclosed systems during a chemical reaction given the balanced symbol equation for the reaction and explain these changes in terms of the particle model.
What does the term uncertainty mean?	Whenever a measurement is made there is always some uncertainty about the result obtained.	Whenever a measurement is made there is always some uncertainty about the result obtained.
How would you represent the distrubtion of results to make estimations of uncertainty?	To represent the distrubution of results and make estimations of uncertainty you should use error bars on a graph.	Students should be able to represent the distribution of results and make estimations of uncertainty
A pippette has an uncertainty of /-0.01mL. It is used three times in a practical. What is the mean measure of uncertainty?	The uncertainty of a pippette that is used three times is = 3 x 0.01 = /- 0.03mL	Students should be able to use the range of a set of measurements about the mean as a measure of uncertainty.
(HT only) Chemical amounts are measured in moles. What is the symbol of the unit for moles?	The symbol for the unit mole is mol.	Chemical amounts are measured in moles. The symbol for the unit mole is mol.
(HT only)How can we calculate the mass of one mole of a substance?	The mass of one mole of a substance is equal to its relative formula mass in grams. Eg. CO2 Mr = 44 : so 1 Mole of CO2 = 44g	How the mass of one mole of a substance calculated.
(HT only)If you have one mole each of two different substances, what will they share in common?	One mole of a substance contains the same number of the stated particles, atoms, molecules or ions as one mole of any other substance.	One mole of a substance contains the same number of the stated particles, atoms, molecules or ions as one mole of any other substance.
(HT only)What does Avogadro's constant represent?	The total number of particles/atoms/molecules/ions within one mole of a substance.	The number of atoms, molecules or ions in a mole of a given substance is the Avogadro constant.
(HT only)What is the value of Avogadro's constant?	1 mole = 6.02 x 1023 particles/atoms/molecules/ions of a substance	The value of the Avogadro constant is 6.02 x 1023 per mole.
(HT only)Would there be any difference in the number of atoms in one mole of carbon (C) compared with the number of one mole of molecules of carbon dioxide (CO2)?	Measurement of amounts in moles can apply to atoms, molecules, ions, electrons, formulae and equations, for example that in one mole of carbon (C) the number of atoms is the same as the number of molecules in one mole of carbon dioxide (CO2).	Students should understand that the measurement of amounts in moles can apply to atoms, molecules, ions, electrons, formulae and equations, for example that in one mole of carbon (C) the number of atoms is the same as the number of molecules in one mole of carbon dioxide (CO2).
(HT only)Calculate the mass of one mole of C2H6	The relative formula mass (Mr) of C2H6 = 30 Therefore the mass of 1 mol C2H6 = 30g	Students should be able to use the relative formula mass of a substance to calculate the number of moles in a given mass of that substance and vice versa.
What units are used for the measurement of concentration of a solution?	The standard measures of concentration of a solution are: grams per dm3 (g/dm3) or moles per dm3 (mol/dm3)	Many chemical reactions take place in solutions. The concentration of a solution can be measured in mass per given volume of solution, eg grams per dm3 (g/dm3).
What is the concentration of a solution that has 37g of solute dissolved in 100cm3? Give your answer in dm3.	The concentration would be 37g / 100cm3. To convert this to dm3 divide answer by 1000 = 0.0037g/dm3.	Students should be able to calculate the mass of solute in a given volume of solution of known concentration in terms of mass per given volume of solution
(HT only) What is the equation that relates the mass of a solute, the volume of a solution and the concentration of the solution?	concentration of solution (g/dm3) = mass of a solute (g) / volume of solution (dm3)	Students should be able to (HT only) explain how the mass of a solute and the volume of a solution is related to the concentration of the solution.
Why industrially is high atom economy important?	It is important for sustainable development and for economic reasons to use reactions with high atom economy.	It is important for sustainable development and for economic reasons to use reactions with high atom economy.
(HT only)Balance the equation and calculate the mass of the reactants and products of the balanced symbol equation: H2O2 --> H20 02	2H2O2 --> 2H20 02 The mass of the reactants is 68, the mass of the reactants is also 68	The masses of reactants and products can be calculated from balanced symbol equations.
(HT only)In the following equation: Mg 2HCI --> MgCI2 H2 What is the ratio of magnesium (Mg) atoms react in comparison to that of hydrochloric acid (HCl)?	1:2 This is because chemical equations can be interpreted in terms of moles. Mg + 2HCI --> MgCI2 + H2 The equation shows that one mole of magnesium (Mg) reacts with two moles of hydrochloric acid (HCl)	Chemical equations can be interpreted in terms of moles. For example: Mg + 2HCI --> MgCI2 + H2 shows that one mole of magnesium reacts with two moles of hydrochloric acid to produce one mole of magnesium chloride and one mole of hydrogen gas.
(HT only)CaCO3 2HCl ---> CaCl2 CO2 H2O Use the above equation to determine the mass of carbon dioxide produced if you react 10g of calcium carbonate with an excess of hydrochloric acid?	4.4g of CO2 is produced	Students should be able to calculate the masses of substances shown in a balanced symbol equation
(HT only)Calculate the mass of iron produced when 32g of iron (III) oxide is completely reduced by aluminium. The reaction is shown in the symbol equation: Fe2O3 2Al ? 2Fe Al2O3	When 32g of iron (III) oxide is reduced by aluminium 22.4g of iron is produced	Students should be able to calculate the masses of reactants and products from the balanced symbol equation and the mass of a given reactant or product.
(HT only)How can you use the massess of reactants and products to balance a symbol equation?	The balancing numbers in a symbol equation can be calculated from the masses of reactants and products by converting the masses in grams to amounts in moles and converting the numbers of moles to simple whole number ratios.	The balancing numbers in a symbol equation can be calculated from the masses of reactants and products by converting the masses in grams to amounts in moles and converting the numbers of moles to simple whole number ratios.
(HT only) Reactants Sb = 488g Cl2 = 426g Products SbCl3= 914g Complete a symbol equation for the reaction above using the masses to balance the equation.	2Sb + 3Cl2 ---> 2SbCl3	Students should be able to balance an equation given the masses of reactants and products.
(HT only)How do you rearrange the moles equation to find the relative formulat mass? Moles = mass / RFM	The moles equation can be rearranged to find RFM = mass / moles	Students should be able to change the subject of a mathematical equation.
(HT only)What is meant when a reactant is said to be in excess?	An excess reactant is any reactant in a chemical reaction with a greater amount than necessary to react completely with the all other reactants.	In a chemical reaction involving two reactants, it is common to use an excess of one of the reactants to ensure that all of the other reactant is used.
What is meant when a reactant is described as a limiting reactant?	A limiting reactant is a reactant that when completely used up the reaction will cease. This is because it limits the amount of products that can be made.	The reactant that is completely used up is called the limiting reactant because it limits the amount of products.
(HT only) 2H2 O2 --> 2H2O You react 10g of oxygen with 10g of hydrogen. Only 11.25g of product is made the rest of the reactants remain unused. Suggest why the full mass of reactants did not react. What is the leftover unreacted substance?	Oxygen is the limiting reactant in this example. Once all of the oxygen is used up the reaction will be unable to continue. Hydrogen therefore we would describe as being in excess, so the 8.75g of leftover reactant would be unused hydrogen that was not used up during the chemical reaction.	Students should be able to explain the effect of a limiting quantity of a reactant on the amount of products it is possible to obtain in terms of amounts in moles or masses in grams.
(Chem only) Suggest why it is not always possible obtain the calculated amount of product from a reaction?	You may not always get the maximum yield because the reaction may not go to completion because it is reversible, some of the product may be lost when it is separated from the reaction mixture; or some of the reactants may react in ways different to the expected reaction.	Even though no atoms are gained or lost in a chemical reaction, it is not always possible to obtain the calculated amount of a product because: ??? the reaction may not go to completion because it is reversible ??? some of the product may be lost when it is separated from the reaction mixture; ? some of the reactants may react in ways different to the expected reaction.
(Chem only) What does the term yield refer to?	The amount of product obtained	The amount of a product obtained is known as the yield.
(Chem only) What is percentage yield?	When the actual yield obtained is compared with the maximum theoretical yield of a reaction is expressed as a percentage, it is called the percentage yield.	When compared with the maximum theoretical amount as a percentage, it is called the percentage yield. % Yield = Mass of product actually made / Maximum theoretical mass of product ? 100
(Chem only) What is the formula for calculating percentage yield?	% Yield = Mass of product actually made / Maximum theoretical mass of product ? 100	Students should be able to calculate the percentage yield of a product from the actual yield of a reaction
(Chem only) What mass of carbon dioxide is formed when 12 g of carbon is burned in air?	1.Write out the equation for the reaction. Make sure it is balanced. C O2 -> CO2 (Carbon is the known, carbon dioxide is the unknown) 2.Work out the relative masses of the substances needed in the calculation. Mass of carbon = 12, mass of carbon dioxide = 44 3.Convert the relative masses into the units in the question. Mass of carbon = 12 g, mass of carbon dioxide is 44 g 4.Find the ratio by dividing both numbers by the smallest number. For carbon 12 ? 12 = 1, for carbon dioxide 44 ? 12 = 3.67 5.Find the mass of the unknown by multiplying the mass of the known by the ratio of the unknown. 3.67 ? 12 = 44 g	(HT only) calculate the theoretical mass of a product from a given mass of reactant and the balanced equation for the reaction.
(Chem only) What is atom economy a measure of?	The amount of starting materials that end up as useful products.	The atom economy (atom utilisation) is a measure of the amount of starting materials that end up as useful products.
(Chem only) What is the formula for calculating percentage atom economy?	The percentage atom economy of a reaction is calculated using the balanced equation for the reaction as follows: Relative formula mass of desired product from equation / Sum of relative formula masses of all reactants from equation ? 100	The percentage atom economy of a reaction is calculated using the balanced equation for the reaction as follows: Relative formula mass of desired product from equation / Sum of relative formula masses of all reactants from equation ? 100
(Chem only) Hydrazine (N2H4) is used in some rocket fuels. Two different methods can be used to manufacture hydrazine. The reactions are: NH2Cl NH3 ? N2H4 HCl 2NH3 H2O2 ? N2H4 2H2O Calculate the atom economy for each reaction	1) Mr of N2H4 = 32 2) Sum of Mr all reactants in equation 1= 68.5 3) (32 / 68.5 ) x100 46.7% 4) Sum of Mr all reactants in equation 2 = 68 5) (32/68) x 100 = 47%	Students should be able to calculate the atom economy of a reaction to form a desired product from the balanced equation
(Chem only) How can a chemist in a chemical plant that makes rocket fuel prevent waste products being formed?	(HT) A chemist can prevent waste rocket fuel being formed by Choose a reaction with few/no other products.	(HT only) explain why a particular reaction pathway is chosen to produce a specified product given appropriate data such as atom economy (if not calculated), yield, rate, equilibrium position and usefulness of by-products.
(Chem only) What is mol/dm3 the unit of measurement for?	mol/dm3 is a measure of concentration. It tells us how many moles of that substance you would find in a dm3	The concentration of a solution can be measured in mol/dm3.
(Chem only) How can we calculate the number of moles of solute in a given volume of a solution?	The amount in moles of solute of solute in a given volume of solution can be calculated from its concentration in mol/dm3 multiplied by the volume of the solution in dm3.	The amount in moles of solute or the mass in grams of solute in a given volume of solution can be calculated from its concentration in mol/dm3.
(Chem only) What technique can we use if the volumes of two solutions that react completely are known and the concentration of one solution is known, to calculate the concentration of the other solution.	A titration reaction	If the volumes of two solutions that react completely are known and the concentration of one solution is known, the concentration of the other solution can be calculated.
(Chem only) How can we calculate the mass of a solute within a solution if we know the concentration in mol/dm3?	mass of solute = (concentration (mol dm-3) / relative formula mass) x volume of solution (dm3)	Students should be able to explain how the concentration of a solution in mol/dm3 is related to the mass of the solute and the volume of the solution
(Chem only) What is the difference between a strong and weak acid?	A strong acid will fully dissociate from all of its H ions whereas a weak acid won't	Opportunities within titrations including to determine concentrations of strong acids and alkalis. (WS)
(Chem only) Do all gases occupy the same volume?	Equal amounts in moles of gases occupy the same volume under the same conditions of temperature and pressure.	Equal amounts in moles of gases occupy the same volume under the same conditions of temperature and pressure.
(Chem only) What volume does one mole of any gas occupy at room temperature and pressure?	A single mole of any gas will occupy 24dm3	The volume of one mole of any gas at room temperature and pressure (20oC and 1 atmosphere pressure) is 24 dm3.
(Chem only) How could you calculate the volume a gas would occupy if you were given the mass of gas made?	1) Calculate the total number of moles of that gas you have (Moles = Mass (g) / Mr) 2) Then calulate the volume that gas would occupy. Volume of gas (dm3) = Moles x 24	The volumes of gaseous reactants and products can be calculated from the balanced equation for the reaction.
(Chem only) If you have 88g of CO2. What volume would it occupy?	1) Calculate moles first: moles = mass /Mr = 88/44 = 2 2) Calculate the volume of gas made: Volume of gas = Moles x 24 = 2x24 = 48dm3	Students should be able to calculate the volume of a gas at room temperature and pressure from its mass and relative formula mass
(Chem only) In the reaction CH4 2O2 ? CO2 2H2O (at rtp) what volume of water vapour is produced when 2.4 dm3 of methane burns?	1) Rearrange volume equation for moles to find moles of methane reacting: moles (methane) = volume / 24 moles (methane) = 2.4 / 24 moles (methane) = 0.1 2) Identify molar ratio for reactants and products in question: 1 mole of methane products 2 moles of water, therefore 1:2 ratio 3) Deduce the moles of water using ratio: 0.1 x 2 = 0.2 moles 4) calculate volume of water vapour: volume of gas = moles x 24 volume of gas = 0.2 x 24 = 4.8dm3	Students should be able to calculate volumes of gaseous reactants and products from a balanced equation and a given volume of a gaseous reactant or product
(Chem only) Rearrange the volume of gas equation to calculate the number of moles	Rearrange volume equation for moles to find moles of methane reacting: moles (methane) = volume / 24	Students should be able to change the subject of a mathematical equation.
What does the reactivity of a metal depend on?	The reactivity of a metal is related to its tendency to form positive ions.	The reactivity of a metal is related to its tendency to form positive ions.
How can the reactivity of group 1 metals be compared using a practical investigation?	Group 1 metal reactivity can be compared by observing their reactivity with water and dilute acids qualitatively by looking at the amount of gas produced using a magnifying glass or quantitatively by measuring the temperature changes.	The metals potassium, sodium, lithium, calcium, order of reactivity is from their reactions with water and dilute acids.
What happens when a metal reacts with oxygen?	Metals react with oxygen to produce metal oxides.	Metals react with oxygen to produce metal oxides.
What happens to metals in an oxidation reaction?	In oxidation reactions metals gain oxygen and looses electrons.	The reactions are oxidation reactions because the metals gain oxygen.
What is meant by the term 'reduction'?	Reduction is the loss of oxygen and gain of electrons.	Students should be able to explain reduction and oxidation in terms of loss or gain of oxygen.
What happens in terms of electrons during reduction and oxidation reactions?	During oxidation reactions substances loose/donate electrons and in reduction reactions substanced gain electrons.	Oxidation is the loss of electrons and reduction is the gain of electrons.
Why is potassium more reactive than lithium?	Potassium is more reactive than lithium because it can form a postive ion easier. This is because the attraction between the outside electron and the nuclues is far lower in potassium than lithium. This is because potassium is a bigger atom with more electron shells, creating more sheilding of the electrostatic attraction.	Students should be able to explain how the reactivity of metals with water or dilute acids is related to the tendency of the metal to form its positive ion
What happens during a displacement reaction?	In a displacement reaction a more reactive metal can displace a less reactive metal from a compound.	A more reactive metal can displace a less reactive metal from a compound.
What would the independent, dependent and control variables be for a quantitative investigation into the reactivity of metals?	To investigate the reactivity of metals quantitatively the independent variable would be the type of metal. The dependent variable would be the temperature increase. The control variables would be the surface area of the metal, the volume and concentration of the water/acid, the temperature of the reactants and the mass of the metal.	Students should be able to deduce an order of reactivity of metals based on experimental results.
Where in the reactivity series does carbon appear and which elements can be displaced by carbon?	The order of reactivity including non metals is: Pottassium, sodium, lithium, calcium, magnesium, aluminium, carbon, zinc, iron, hydrogen, copper, silver, gold. Only elements below carbon in the reactivity series can be displaced by carbon.	The non-metals hydrogen and carbon are often included in the reactivity series.
What conditions are standard when investigating the reactivity of metals with water and acids?	The reactions of metals with water and acids are limited to room temperature and do not include reactions with steam.	The reactions of metals with water and acids are limited to room temperature and do not include reactions with steam.
What is the list of metals (and non-metals) in the reactivity series, from most reactive to least reactive?	Potassium, sodium, lithium, calcium, magnesium, aluminium, carbon, zinc, iron, hydrogen, copper, silver, gold.	Metals can be arranged in order of their reactivity in a reactivity series.
How do each of the following metals react with each of water and dilute acids: potassium, sodium, lithium, calcium, magnesium, zinc, iron and copper?	Lithium, sodium and potassium have vigorous reactions with cold water and explosive reactions with dilute acids. Calcium, magnesium have less vigorous reactions with water and dilute acids but it is possible to see gas being produced. Zinc, iron and copper have far less vigorous reactions, decreasing in reactivity.	Students should be able to recall and describe the reactions, if any, of potassium, sodium, lithium, calcium, magnesium, zinc, iron and copper with water or dilute acids and where appropriate, to place these metals in order of reactivity
Write the ionic equation for the displacement reaction between copper ions and magnesium	The equation for the displacement reaction between copper ions and magnesium is: Cu2 Mg --> Mg2 Cu	Student should be able to write ionic equations for displacement reactions
Why are metals such as gold found in the Earth as the metal itself?	Gold is found in the Earth as the metal itself as it is unreactive.	Unreactive metals such as gold are found in the Earth as the metal itself but most metals are found as compounds that require chemical reactions to extract the metal.
How can metals less reactive than carbon be extracted from their oxides?	Metals less reactive than carbon can be extracted from their oxides by reduction with carbon.	Metals less reactive than carbon can be extracted from their oxides by reduction with carbon.
What is meant by 'reduction' in terms of oxygen?	Reduction involves the loss of oxygen.	Reduction involves the loss of oxygen.
What substance can be used to extract the lesser reactive metals?	Carbon can be used to extract the lesser reactive metals.	Knowledge and understanding are limited to the reduction of oxides using carbon.
What type of reaction is it when electrons are transferred from one species to another?	When electrons are transferred from one species to another this is called a redox reaction.	Knowledge of the details of processes used in the extraction of metals is not required.
Identify the species that are oxidised and reduced in the half equations below: Cu2 Mg --> Mg2 Cu	The oxidation half equation is: Mg --> Mg2 2e- The reduction half equation is: Cu2 2e- --> Cu	Students should be able to identify in a given reaction, symbol equation or half equation which species are oxidised and which are reduced.
What are the products when acids react with metals?	Acids react with some metals to produce salts and hydrogen.	Acids react with some metals to produce salts and hydrogen.
(HT only) What type of reaction occurs when acids react with metals?	(HT) When acids react with metals there is a transfer of electrons so this is a redox reaction.	(HT only) Students should be able to explain in terms of gain or loss of electrons, that these are redox reactions
(HT only) In a reaction between copper (II) oxide and carbon, where does each of oxidation and reduction happen?	Carbon is oxidised by gaining oxygen to form carbon dioxide. Copper (in CuO) is reduced by losing oxygen to form copper metal. Copper has changed from Cu2 (in CuO) to Cu(s) and so has gained electrons. Cu2 (aq) 2e-(aq) arrow Cu(s)	Students should be able to identify which species are oxidised and which are reduced in given chemical equations. (HT only)
When an acid (such as hydrochloric acid) reacts with an alkali or a base (such as sodium hydroxide), what will the two products be?	When an acid reacts with an alkali or base it produces salts and water.	Acids are neutralised by alkalis (eg soluble metal hydroxides) and bases (eg insoluble metal hydroxides and metal oxides) to produce salts and water
What products are made when an acid reacts with a metal carbonate?	Acids are neutralised by metal carbonates to produce salts, water and carbon dioxide.	Acids are neutralised by metal carbonates to produce salts, water and carbon dioxide.
What factors affect the type of salt produced in a reaction between an acid and a base or alkali?	The particular salt produced in any reaction between an acid and a base or alkali depends on: - the acid used (hydrochloric acid produces chlorides, nitric acid produces nitrates, sulfuric acid produces sulfates) - the positive ions in the base, alkali or carbonate.	The particular salt produced in any reaction between an acid and a base or alkali depends on: - the acid used (hydrochloric acid produces chlorides, nitric acid produces nitrates, sulfuric acid produces sulfates) - the positive ions in the base, alkali or carbonate.
What two products would be made when zinc oxide reacts with dilute hydrochloric acid?	The two products that would be made when zinc oxide reacts with dilute hydrochloric acid are zinc chloride and water.	Students should be able to predict products from given reactants
What examples of solid insoluble substances react with acids to form soluble salts?	Soluble salts can be made from acids by reacting them with solid insoluble substances, such as metals, metal oxides, hydroxides or carbonates.	Soluble salts can be made from acids by reacting them with solid insoluble substances, such as metals, metal oxides, hydroxides or carbonates.
When an excess of metal oxide reactant is added to an acid, how can the pure salt solution be collected?	The solid is added to the acid until no more reacts and the excess solid is filtered off to produce a solution of the salt.	(WS) The solid is added to the acid until no more reacts and the excess solid is filtered off to produce a solution of the salt.
What process is used to produce solid soluble salts from salt solutions?	Salt solutions can be crystallised to produce solid salts.	Salt solutions can be crystallised to produce solid salts.
What are the typical steps are involved in preparing a pure, dry sample of silver chloride from silver nitrate and sodium chloride?	Silver chloride is insoluble - you can see this from the table. You need a soluble silver salt and a soluble chloride salt to make it. Silver nitrate and sodium chloride are both soluble. When you mix their solutions together, you make soluble sodium nitrate and insoluble silver chloride: silver nitrate sodium chloride → sodium nitrate silver chloride AgNO3(aq) NaCl(aq) → NaNO3(aq) AgCl(s) The silver chloride appears as tiny particles suspended in the reaction mixture - it forms a precipitate. The precipitate can be filtered, washed with water on the filter paper, and then dried in an oven.	Students should be able to describe how to make pure, dry samples of named soluble salts from information provided.
What would the formula be if the following ions reacted to form salts: a) Mg Cl- b) Cu2 S2- c) Fe2 I-	a) MgCl2 b) CuS c) FeI2	Students should be able to use the formulae of common ions to deduce the formulae of salts.
In what way can universal indicator be used to measure the approximate pH of a solution?	Universal indicator is used to measure the approximate pH of a solution as when it is added to a solution strongly acidic solutions appear red, weakly acidic solutions appear orange/yellow, neutral solutions appear green, weakly alkaline solutions appear blue and strongly alkaline solutions appear purple.	(WS) Students should be able to describe the use of universal indicator or a wide range indicator to measure the approximate pH of a solution
If a substance has the following pH is it classified as acid, alkali or neutral: 1) pH 3 2) pH 11 3) pH 7	1) pH 3 = acid 2) pH 11 = alkali 3) pH 7 = neutral	(WS) Students should be able to use the pH scale to identify acidic or alkaline solutions.
What ions are produced in alkalis in aqueous solutions?	Aqueous solutions of alkalis contain hydroxide ions (OH-).	Aqueous solutions of alkalis contain hydroxide ions (OH-).
What happens to strong acids in an aqueous solution in terms of ionisation?	A strong acid is completely ionised in aqueous solution. Examples of strong acids are hydrochloric, nitric and sulfuric acids.	A strong acid is completely ionised in aqueous solution. Examples of strong acids are hydrochloric, nitric and sulfuric acids.
What happens to weak acids in an aqueous solution in terms of ionisation?	A weak acid is only partially ionised in aqueous solution. Examples of weak acids are ethanoic, citric and carbonic acids.	A weak acid is only partially ionised in aqueous solution. Examples of weak acids are ethanoic, citric and carbonic acids.
What ions are produced in acids in aqueous solutions?	Acids produce hydrogen ions (H ) in aqueous solutions.	Acids produce hydrogen ions (H ) in aqueous solutions.
When an acid is stronger, what effect does this have on the pH?	For a given concentration of aqueous solutions, the stronger an acid, the lower the pH.	For a given concentration of aqueous solutions, the stronger an acid, the lower the pH.
What happens to the hydrogen ion concentration of a solution when pH decreases by one unit?	As the pH decreases by one unit, the hydrogen ion concentration of the solution increases by a factor of 10.	As the pH decreases by one unit, the hydrogen ion concentration of the solution increases by a factor of 10.
What is meant by 'dilute' and 'concentrated' (in terms of amount of substance) and 'weak acid' and 'strong acid' (in terms of the degree of ionisation)?	The strength of an acid is a measure of the degree of its ionisation - strong acids are fully ionised but weak acids are only partly ionised. Remember that the opposite of strong is weak. The concentration of an acid is a measure of the number of moles of acid in 1 dm3 of acid solution. For example, 2 mol/dm3 hydrochloric acid is twice as concentrated as 1 mol/dm3 hydrochloric acid or 1 mol/dm3 ethanoic acid. Remember: the opposite of concentrated is dilute.	Students should be able to use and explain the terms dilute and concentrated (in terms of amount of substance), and weak and strong (in terms of the degree of ionisation) in relation to acids
How is the reaction between hydrogen ions and hydroxide ions to produce water presented as an equation?	This reaction can be represented by the equation: H (aq) OH-(aq) -> H2O(l)	This reaction can be represented by the equation: H (aq) OH-(aq) -> H2O(l)
How is water produced in a neutralisation reaction between an acid and an alkali in terms of ions?	In neutralisation reactions between an acid and an alkali, hydrogen ions react with hydroxide ions to produce water.	In neutralisation reactions between an acid and an alkali, hydrogen ions react with hydroxide ions to produce water.
What piece of digital equipment can be used to measure the pH of a solution?	A digital pH probe can be used to measure the acidity or alkalinity of a solution more accurately and precisely than universal indicator.	The pH scale, from 0 to 14, is a measure of the acidity or alkalinity of a solution, and can be measured using universal indicator or a pH probe.
What pH values do each of acidic, alkaline and neutral solutions have?	A solution with pH 7 is neutral. Aqueous solutions of acids have pH values of less than 7 and aqueous solutions of alkalis have pH values greater than 7.	A solution with pH 7 is neutral. Aqueous solutions of acids have pH values of less than 7 and aqueous solutions of alkalis have pH values greater than 7.
A sample of vinegar contains 0.1 mol/dm3 ethanoic acid. What is its concentration in g/dm3? (The relative formula mass, Mr, of ethanoic acid is 60)	concentration in g/dm3 = concentration in g/dm3 ? Mr concentration = 0.1 ? 60 = 6 g/dm3 Answer 6 g/dm3	(MS) (HT Only) calculate the chemical quantities in titrations involving concentrations in mol/dm3 and in g/dm3.
25 cm3 of dilute hydrochloric acid is neutralised by 20 cm3 of 0.5 mol/dm3 sodium hydroxide. What is the concentration of the hydrochloric acid?	Step 1: Convert volumes to dm3 25 cm3 of HCl = 25 /1000 = 0.025 dm3 20 cm3 of NaOH = 20 / 1000 = 0.020 dm3 Step 2: Determine the number of moles of sodium hydroxide moles of NaOH = concentration ? volume moles of NaOH = 0.5 x 0.020 = 0.010 mol Step 3: Work out the number of moles of acid using the balanced equation HCl(aq) NaOH(aq) ? NaCl(aq) H2O(l) In this reaction, one mole of HCl reacts with one mole of NaOH. This is a 1:1 ratio. Therefore, in our titration, 0.010 mol of NaOH must neutralise 0.010 mol of HCl. Step 4: Calculate the concentration of the acid concentration of HCl = number of moles / volume concentration of HCl = 0.010 / 0.025 = 0.4 mol/dm3 Answer The concentration of the HCl is 0.4 mol/dm3.	(MS) (HT only) determination of the concentration of one of the solutions in mol/dm3 and g/dm3 from the reacting volumes and the known concentration of the other solution.
How can the volumes of acid and alkali solutions that react with each other be measured?	The volumes of acid and alkali solutions that react with each other can be measured by titration using a suitable indicator.	The volumes of acid and alkali solutions that react with each other can be measured by titration using a suitable indicator.
What does conservation of energy mean?	Energy is conserved in chemical reactions. The amount of energy in the universe at the end of a chemical reaction is the same as before the reaction	Energy is conserved in chemical reactions. The amount of energy in the universe at the end of a chemical reaction is the same as before the reaction takes place.
In what circumstance is energy transferred to the surroundings during a chemical reaction?	If a reaction transfers energy to the surroundings the product molecules must have less energy than the reactants, by the amount transferred.	If a reaction transfers energy to the surroundings the product molecules must have less energy than the reactants, by the amount transferred.
What happens to the energy in an exothermic reaction?	An exothermic reaction is one that transfers energy to the surroundings so the temperature of the surroundings increases.	An exothermic reaction is one that transfers energy to the surroundings so the temperature of the surroundings increases.
What are three examples of exothermic reactions?	Exothermic reactions include combustion, many oxidation reactions and neutralisation.	Exothermic reactions include combustion, many oxidation reactions and neutralisation.
What is an example of an exothermic reaction in everyday life?	Everyday uses of exothermic reactions include self-heating cans and hand warmers.	Everyday uses of exothermic reactions include self-heating cans and hand warmers.
What happens to the energy in an endothermic reaction?	An endothermic reaction is one that takes in energy from the surroundings so the temperature of the surroundings decreases.	An endothermic reaction is one that takes in energy from the surroundings so the temperature of the surroundings decreases.
What are three examples of endothermic reactions?	Endothermic reactions include thermal decompositions and the reaction of citric acid and sodium hydrogencarbonate	Endothermic reactions include thermal decompositions and the reaction of citric acid and sodium hydrogencarbonate. Some sports injury packs are based on endothermic reactions.
What is an example of an endothermic reaction in everyday life?	Everyday uses of endothermic reactions are some sports injury (ice) packs.	Some sports injury packs are based on endothermic reactions.
When a chemical reaction occurs and the temperature of the surroundings has increased, is it an exothermic or endothermic reaction?	When a chemical reaction occurs and the temperature of the surroundings has increased the chemical reaction is exothermic.	Students should be able to distinguish between exothermic and endothermic reactions on the basis of the temperature change of the surroundings
What are the advantages of using exothermic reactions for hand warmers?	The advantages of using exothermic reactions for hand warmers is that they keep your hands warm because they release thermal energy to the surroundings.	Students should be able to evaluate uses and applications of exothermic and endothermic reactions given appropriate information.
What is the temperature change of the solution if the starting temperature was 20 degrees and the end temperature was -5 degrees. State if this is endothermic or exothermic.	The energy change would be (-)15 degrees. This is an endothermic reaction.	Limited to measurement of temperature change. Calculation of energy changes or ?H is not required.
Why do some collisions between reactant particles not result in a product forming?	Chemical reactions can occur only when reacting particles collide with each other and with sufficient energy. This doesn't always happen.	Chemical reactions can occur only when reacting particles collide with each other and with sufficient energy.
What does the term activation energy mean?	The minimum amount of energy that particles must have to react is called the activation energy.	The minimum amount of energy that particles must have to react is called the activation energy.
What information can be shown in a reaction profile?	Reaction profiles can be used to show the relative energies of reactants and products, the activation energy and the overall energy change of a reaction.	Reaction profiles can be used to show the relative energies of reactants and products, the activation energy and the overall energy change of a reaction.
What would the simple reaction profile for an exothermic reaction look like?	For an exothermic reaction the reaction profile would show the energy level for the reactants to be lower than the energy level for the products. A curved line is used to show the activation energy required for the reaction (this is higher than the products energy level)	Students should be able to draw simple reaction profiles (energy level diagrams) for exothermic and endothermic reactions showing the relative energies of reactants and products, the activation energy and the overall energy change, with a curved line to show the energy as the reaction proceeds
What would the simple reaction profile for an endothermic reaction look like?	For an endothermic reaction the reaction profile would show the energy level for the reactants to be higher than the energy level for the products. A curved line is used to show the activation energy required for the reaction (this is higher than the reactants energy level)	Students should be able to use reaction profiles to identify reactions as exothermic or endothermic
What information does the activation energy provide?	The activation energy is the energy needed for a reaction to occur.	Students should be able to explain that the activation energy is the energy needed for a reaction to occur.
What energy transfers occur during breaking bonds of reactants and forming new bonds of products?	During a chemical reaction energy must be supplied to break bonds in the reactants and energy is released when bonds in the products are formed.	During a chemical reaction energy must be supplied to break bonds in the reactants and energy is released when bonds in the products are formed.
What information can bond energies provide?	Bond energies tell us the energy needed to break bonds and the energy released when bonds are formed.	The energy needed to break bonds and the energy released when bonds are formed can be calculated from bond energies.
How is the overall energy change of a reaction calculated?	The overall energy change is calculated by working out the difference between the sum of the energy needed to break bonds in the reactants and the sum of the energy released when bonds in the products are formed is the overall energy change of the reaction.	The difference between the sum of the energy needed to break bonds in the reactants and the sum of the energy released when bonds in the products are formed is the overall energy change of the reaction.
What happens in an exothermic reaction in terms of energy, bond making and bond breaking?	In an exothermic reaction, the energy released from forming new bonds is greater than the energy needed to break existing bonds.	In an exothermic reaction, the energy released from forming new bonds is greater than the energy needed to break existing bonds.
What happens in an endothermic reaction in terms of energy, bond making and bond breaking?	In an endothermic reaction, the energy needed to break existing bonds is greater than the energy released from forming new bonds.	In an endothermic reaction, the energy needed to break existing bonds is greater than the energy released from forming new bonds.
What is the energy transferred in the following chemical reaction: hydrogen bromide decomposing to form hydrogen and bromine? 2 ? (H?Br) ? H?H Br?Br The bond energies relevant to this reaction are shown below: H?Br 366 kJ/mol H?H 436 kJ/mol Br?Br 193kJ/mol	1.Energy in = 2 ? 366 = 732 kJ/mole 2.Energy out = 436 + 193 = 629 kJ/mole 3.Energy change = in ? out = 732 ? 629 = +103 kJ/mole The energy change is positive, showing that energy is taken in from the surroundings in an endothermic reaction.	Students should be able to calculate the energy transferred in chemical reactions using bond energies supplied.
How can the amount of energy transferred during a chemical reaction be measured using a practical?	A calorimeter can be used to measure the energy change of a reaction. Equipment needed: polystyrene cup, lid, thermometer, measuring cylinder, spatula. Add 10mL of solution to the beaker and record the starting temperature. Add one spatula of the powder of the reactants. Record the change in temperature. Subtract the end temperature from the start temperature.	Required practical 4 - temperature change in reactions (AT skills 1,3,5,6)
Why are chemical cells useful?	Cells contain chemicals which react to produce electricity.	Cells contain chemicals which react to produce electricity.
What factors can affect the voltage produced by a chemical cell?	The voltage produced by a cell is dependent upon a number of factors including the type of electrode and electrolyte.	The voltage produced by a cell is dependent upon a number of factors including the type of electrode and electrolyte.
How can a simple chemical cell be made?	A simple cell can be made by connecting two different metals in contact with an electrolyte.	A simple cell can be made by connecting two different metals in contact with an electrolyte.
What is the structure of a battery like?	Batteries consist of two or more cells connected together in series to provide a greater voltage	Batteries consist of two or more cells connected together in series to provide a greater voltage.
Why do re-chargeable cells and batteries stop working?	In non-rechargeable cells and batteries the chemical reactions stop when one of the reactants has been used up.	In non-rechargeable cells and batteries the chemical reactions stop when one of the reactants has been used up. Alkaline batteries are non-rechargeable.
How can re-chargeable cells and batteries be re-charged?	Rechargeable cells and batteries can be recharged because the chemical reactions are reversed when an external electrical current is supplied.	Rechargeable cells and batteries can be recharged because the chemical reactions are reversed when an external electrical current is supplied.
Which cell would be the best choice to use to power a machine? Cell A produces 0.01V of energy and cell B produces 0.20V of energy. Give a reason for your answer.	Cell B would be the better choice to power a machine as it produces more electricity.	Students should be able to interpret data for relative reactivity of different metals and evaluate the use of cells.
What type of batteries are non-rechargeable?	Alkaline batteries are non-rechargable.	Students do not need to know details of cells and batteries other than those specified.
How do fuel cells produce a potential difference?	Fuel cells are supplied by an external source of fuel (eg hydrogen) and oxygen or air. The fuel is oxidised electrochemically within the fuel cell to produce a potential difference.	Fuel cells are supplied by an external source of fuel (eg hydrogen) and oxygen or air. The fuel is oxidised electrochemically within the fuel cell to produce a potential difference.
What sort of reaction occurs in a hydrogen fuel cell?	The overall reaction in a hydrogen fuel cell involves the oxidation of hydrogen to produce water.	The overall reaction in a hydrogen fuel cell involves the oxidation of hydrogen to produce water.
What do hydrogen fuel cells offer alternatives to?	Hydrogen fuel cells offer a potential alternative to rechargeable cells and batteries.	Hydrogen fuel cells offer a potential alternative to rechargeable cells and batteries.
What are the advantages and disadvantages of using hydrogen fuel cells compared with rechargeable cells and batteries?	Similarities: Both convert chemical energy directly into electrical energy using ?spontaneous? redox reactions / Both function in similar ways ? that is, there is a negative electrode where an oxidation half-reaction occurs and a positive electrode where a reduction half-reaction occurs / Both generate electrical energy using chemical energy (compounds in the cells undergo chemical reactions which send electrons into an external circuit) / Both generate a current through an external circuit, which is caused by the separation of the half-reactions part of a full redox reaction / Both are made up of an electrolyte, an anode, and a cathode. Differences: The hydrogen oxygen fuel cell is an energy conversion device while the rechargeable battery is an energy storage device / Fuel cells can only provide electrical energy when reactants (fuel) are constantly provided to the cell (open system) / Rechargeable batteries have chemical energy stored in its parts, in a closed system, and so can provide electricity until its stored chemical energy is used up, at which point the battery requires recharging to renew its chemical energy level. Fuel cells do not require charging, as long as reactants continue to be provided, whereas rechargeable batteries must be charged, which takes the battery out of operation for a period of time / Fuel cells can provide electrical energy for a much longer duration, whereas rechargeable batteries can only provide energy in an intermittent schedule / Electrodes in fuel cells are made of porous material, which allows for the free movement of hydrogen, oxygen, and water, while those in rechargeable batteries are made of solid metal compounds and lattices / Currently, fuel cells are much more expensive than rechargeable batteries, due to the high prices of its individual parts, such as the platinum catalysts / Currently, fuel cells are far larger than rechargeable batteries / Fuel cells are able to generate a large amount of electrical energy, much greater than that produced by rechargeable batteries.	Students should be able to evaluate the use of hydrogen fuel cells in comparison with rechargeable cells and batteries
(HT only) What are the half equations for the electrode reactions in a hydrogen fuel cell?	(HT only) At the cathode (negative electrode): H2(g) – 2e– → 2H (aq) At the anode (positive electrode): 4H (aq) O2(g) 4e– → 2H2O(g)	Students should be able to write the half equations for the electrode reactions in the hydrogen fuel cell. (HT only)
When is an ionic compound able to conduct electricity?	When an ionic compound is melted or dissolved in water, the ions are free to move about within the liquid or solution. These liquids and solutions are able to conduct electricity and are called electrolytes.	When an ionic compound is melted or dissolved in water, the ions are free to move about within the liquid or solution. These liquids and solutions are able to conduct electricity and are called electrolytes.
(HT) What is the balanced half equation for H ? e??? H2	T(HT)he balanced half equation is: 2H ? 2e??? H2	(HT only) Write balanced half equations and ionic equations where appropriate.
What happens at each of the electrodes in electrolysis when an electric current is passed through the electroytes?	Passing an electric current through electrolytes causes the ions to move to the electrodes. Positively charged ions move to the negative electrode (the cathode), and negatively charged ions move to the positive electrode (the anode). Ions are discharged at the electrodes producing elements. This process is called electrolysis.	Passing an electric current through electrolytes causes the ions to move to the electrodes. Positively charged ions move to the negative electrode (the cathode), and negatively charged ions move to the positive electrode (the anode). Ions are discharged at the electrodes producing elements. This process is called electrolysis.
(HT) What happens at the anode and cathode electrodes in the electrolysis of aqueous sodium chloride? (use half equations to help explain)	(HT) At the cathode sodium is formed: 2Na 2e- --> 2Na At the anode chlorine gas is formed: 2Cl- -->Cl2 2e-	(HT only) Throughout Section 4.4.3 Higher Tier students should be able to write half equations for the reactions occurring at the electrodes during electrolysis, and may be required to complete and balance supplied half equations. (MS)
Which electrode as the metals and non metals products found during electrolysis?	During electrolysis the metal product is found at the cathode as this cathode is negatively charged. The non metal product is found at the anode, this this electrode is positively charged.	When a simple ionic compound (eg lead bromide) is electrolysed in the molten state using inert electrodes, the metal (lead) is produced at the cathode and the non-metal (bromine) is produced at the anode.
What would the products be for the electrolysis of the following ionic compounds: 1. NaCl 2. PbBr2 3. NaOH 4. Al2O3	The products of electrolysis would be: 1. H2 (g) Cl2 (g) NaOH (aq) 2. Pb (s) Br2 (g) 3. H2 (g) O2 (g) Na (aq) 4. Al (s) O2 (g)	Students should be able to predict the products of the electrolysis of binary ionic compounds in the molten state.
(HT) What would the half equations be for the electrolysis of NaCl?	(HT) anode: 2Cl– → Cl2 2e- (oxidation) cathode: 2H 2e– → H2 (reduction). NaOH solution is also produced.	(HT only) students should be able to write half equations for the reactions occurring at the electrodes during electrolysis, and may be required to complete and balance supplied half equations for this process . (MS)
What happens at the cathode during electrolysis? Is this an oxidation or reduction reaction?	During electrolysis, at the cathode (negative electrode), positively charged ions gain electrons and so the reactions are reductions.	During electrolysis, at the cathode (negative electrode), positively charged ions gain electrons and so the reactions are reductions.
What happens at the anode during electrolysis? Is this an oxidation or reduction reaction?	At the anode (positive electrode), negatively charged ions lose electrons and so the reactions are oxidation reactions.	At the anode (positive electrode), negatively charged ions lose electrons and so the reactions are oxidation reactions.
What would the half equations be during the electrolysis of PbBr2?	anode: 2Br– → Br2 2e- (oxidation) cathode: Pb2 2e– → Pb (reduction).	Reactions at electrodes can be represented by half equations, for example: 2H 2e- ? H2 and 4OH- ? O2 2H2O 4e- or 4OH- 4e- ? O 2H2O
When is electrolysis used to extract metals from their ores?	Metals can be extracted from molten compounds using electrolysis. Electrolysis is used if the metal is too reactive to be extracted by reduction with carbon or if the metal reacts with carbon.	Metals can be extracted from molten compounds using electrolysis. Electrolysis is used if the metal is too reactive to be extracted by reduction with carbon or if the metal reacts with carbon.
What is the main drawback of using electrolysis to extract metals?	The main drawback of using electrolysis to extract metals is that a large amount of energy is used to melt the compounds and to produce the electrical current.	Large amounts of energy are used in the extraction process to melt the compounds and to produce the electrical current.
How is aluminium extracted from its metal ore (aluminium oxide)?	Aluminium is manufactured by the electrolysis of a molten mixture of aluminium oxide and cryolite using carbon as the positive electrode (anode).	Aluminium is manufactured by the electrolysis of a molten mixture of aluminium oxide and cryolite using carbon as the positive electrode (anode).
Why is a mixture used as the electrolyte in electrolysis?	A mixture is used as the electrolyte in electrolysis as the atoms are not chemically bonded they can be separated.	Students should be able to explain why a mixture is used as the electrolyte
Why does the positive electrode (the anode) need to be replaced regularly?	Oxygen forms at the positive electrodes (anodes). This oxygen reacts with the carbon of the positive electrodes, forming carbon dioxide, and they gradually burn away.	Students should be able to explain why the positive electrode must be continually replaced.
(HT)What are the missing reactants and products of the half equation shown below: Mg2 ___--> _____	(HT) Mg2 2e- --> Mg	(HT only) students should be able to write half equations for the reactions occurring at the electrodes during electrolysis, and may be required to complete and balance supplied half equations for this process . (MS)
Why is hydrogen produced instead of sodium in the electrolysis of NaCl solution?	The ions discharged when an aqueous solution is electrolysed using inert electrodes depend on the relative reactivity of the elements involved. Sodium is more reactive than hydrogen so forms NaOH in solution. Hydrogen gas is discharged at the electrode.	The ions discharged when an aqueous solution is electrolysed using inert electrodes depend on the relative reactivity of the elements involved.
When is hydrogen produced at the negative electrode in electrolysis?	At the negative electrode (cathode), hydrogen is produced if the metal is more reactive than hydrogen.	At the negative electrode (cathode), hydrogen is produced if the metal is more reactive than hydrogen.
When is oxygen not produced at the positive electrode?	At the positive electrode (anode), oxygen is produced unless the solution contains halide ions when the halogen is produced.	At the positive electrode (anode), oxygen is produced unless the solution contains halide ions when the halogen is produced.
Why are hydrogen and oxygen often discharged in the electrolysis of aqueous ionic solutions?	Oxygen and hydrogen gas are discharged because in the aqueous solution water molecules break down producing hydrogen ions and hydroxide ions that are discharged.	This happens because in the aqueous solution water molecules break down producing hydrogen ions and hydroxide ions that are discharged.
What are the three products made in the electrolysis of aqueous sodium chloride?	The three products of the electrolysis of NaCl would be NaOH, Cl2 and H2.	Students should be able to predict the products of the electrolysis of aqueous solutions containing a single ionic compound.
(HT)	(HT)	(HT only) students should be able to write half equations for the reactions occurring at the electrodes during electrolysis, and may be required to complete and balance supplied half equations for this process . (MS)
How can you separate a solution of copper II sulfate to extract low grade copper ores? (include equipment)	Electrolysis can be used to extract low grade copper ores. Equipment needed: DC power supply, wires, graphite electrodes, beaker, copper sulfate solution. Connect the graphite electrodes to the power supply, immerse into the solution and switch on. Wait. copper ions will be collected at cathode and oxygen gas will be collected at the anode.	Required practical 3 - electrolysis (developing hypothesis) (AT skills 3,7,8)

Mod	Number of Questions
0S	10
1B	10
1C	10
1P	10
BI	5