# The mole

The gram formula mass (GFM) of a substance is known as the mass of one mole.

Relative atomic masses of selected elements can be found in the SQA Data Booklet.These can be used to calculate the gram formula mass of a substance.

### Example

What is the mass of one mole of calcium chloride?

To calculate this, work out the formula of calcium chloride then add all the mass numbers together.

One mole of calcium chloride has a mass of 111 g.

Chemists predict the weight of chemical substances using a unit called 'the mole'