Interpreting formulae
A formula gives information about the type and the number of each atom present in a A substance formed when two or more elements are chemically combined..
The formula for sodium sulfate is Na2SO4. It tells you that sodium sulfate contains:
- two sodium atoms
- one sulfur atom
- and four oxygen atoms
The A character (number, letter or symbol) that is set below the normal line of type. numbers refer to the element before them.
Sometimes a formula includes brackets. The atoms inside the brackets are multiplied by the number outside the brackets.
Aluminium sulfate’s formula is Al2(SO4)3. It contains:
- 2 atoms of aluminium
- 3 atoms of sulfur
- 12 atoms of oxygen
