Memory Anchor:

• Students can identify the number of elements in a compound from its formulae.
Students can identify the number of atoms in a compound from its formulae.

Super Challenge:

Stretch:

Challenge:

Key Questions:

1. How do we represent chemicals universally?
   • chemical symbols and formulae for elements and compounds
2. What rules apply to all chemical symbols?
   • Some chemical symbols consist of two letters (as there are more than 26 elements). Chemical symbols start with a capital letter.
3. What does the chemical formulae of a compound show?
   • Compounds have chemical formulae which show the elements in the compound.
4. How can you tell a compound from the formula of it?
   • Compounds have chemical formulae with more than one capital letter in.
5. How can you tell an element from the formula of it?
   • Elements have chemical formulae with only one capital letter in.
6. How can we identify the number of elements in a compound?
   • We identify the number of elements in a compound by counting the number capital letters in the formulae.
7. Identify the number of element and atoms in the following formulae: CO Co NaOH MgO MgSO4 CaCO3 CaCl What are the elements in the above formulae?
   • CO 2 atoms, 2 elements. NaOH 4 atoms, 3 elements. MgO 2 atoms, 2 elements. MgSO4 6 atoms, 3 elements. CaCO3 5 atoms, 3 elements. CaCl 2 atoms, two elements. CO2 carbon and oxygen. NaOH sodium, oxygen and hydrogen. MgO magnesium and oxygen. MgSO4 magnesium, sulfur and oxygen. CaCO3 calcium, carbon and oxygen. CaCl calcium and chlorine.
8. How can you represent a mixture in writing?
   • Mixture formulae have a plus sign in.