What are isotopes?

Atoms of the same element may not be identical. The different forms of an element are called isotopes.

Percentage mass & empirical formula

Calculate how each element in a compound is pulling its weight, and use this to find the chemical formula empirically

Relative atomic mass & molecular mass

Unit-less but meaningful: making sense of the mass of an atom with ratio

The mole & molar mass

Learn how how to count, but in moles