The Mole

What is The Mole?

Within Chemistry, which covers atoms, bonding, reactions, the periodic table, organic chemistry and the chemistry of everyday life, this topic explains The Mole. Chemistry links what you can see in the lab to the particles and bonds behind it, so each topic here shows that link in a model.

Check that you can explain The Mole in your own words and give one example from everyday life. If you can do that, you have understood the core idea.

Understanding The Mole helps you explain why substances behave as they do, from cleaning products and food to medicines.

The Mole in detail

The mole is the unit for amount of substance. One mole contains 6.02 × 10²³ particles (the Avogadro constant) and has a mass in grams equal to the relative formula mass. So 1 mole of water has a mass of 18 g.

The key equation is moles = mass ÷ Mᵣ. Moles allow chemists to count particles by weighing, and they connect balanced equations to real quantities, since the coefficients show the ratio of moles. The mole is the most important quantity for chemical calculations.

How the interactive helps you understand The Mole

Watch the bar chart in the interactive. Use any sliders or buttons it offers to change the values and see how the bar chart responds.

Before you change anything, predict the result. Then change one value at a time and check whether your prediction was right. This is a quick way to build a correct mental model of The Mole.

Real-life uses and examples

• Explain The Mole in an exam by linking the particles involved to what you observe.
• Use The Mole to explain what happens in a lab experiment and why.
• Link The Mole to everyday products such as cleaning agents, food and medicines.

Common mistakes to avoid

• Mixing up the names of substances or ions when you describe The Mole.
• Describing what happens without explaining the particles or bonds involved.
• Learning the definition without testing it. Use the quiz and the interactive to check that you can apply the idea.