Memory Anchor:

• Super Challenge:

  Stretch:

  Challenge:

Key Questions:

1. What are the three states of matter?
   • The three states of matter are solid, liquid and gas.
2. 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.
3. 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.
4. 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.
5. 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.
6. 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.
7. 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.
8. (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.