Define an element?

Describe the structure of an element.

Define the turm compound.

Carbon + oxygen ------

Two oxygens molecules are red.
One carbon molecule is black.
How would you draw this?

Ca(+2), NO (-3) What is the chemical formula of calcium nitrate?

Relative atomic mass (Mr values) Percentage mass of an element in a compound

Mr values of MgCl (2)
Numbers have to be in subscript