A mole of something is 6.02 × 10²³ of it. The mass of a mole of a substance is its relative mass expressed in grams.

The relative formula mass (RFM) of a substance is the sum of the relative atomic masses of all the atoms in a formula.

Avogadro's constant is the number of particles in one mole of a substance (6.02 × 10²³ mol⁻¹)

The mole

Combined science

Three types of chemical reaction

Conservation of mass

Balancing equations

Moles and masses

Uncertainties in measurements: chemistry

Representations of a mole

Mass in a chemical reaction: using moles

Limiting reactants

Determining an equation from given values

Determining an equation experimentally: magnesium oxide

Determining an equation experimentally: sodium hydrogencarbonate

In the Making salts unit, pupils will learn about the production of pure salts, concentration and strength of acids, and what makes acids acidic and how bases can neutralise them.

In the Understanding Chemical Reactions unit, pupils learned about how atoms rearrange during chemical reactions and the conservation of mass.

This unit covers writing chemical formulae, balancing equations, and using the conservation of mass. It includes calculating moles, empirical formulae, relative formula masses, and theoretical yields. Emphasis is on stoichiometry, concentration, gas volumes, and using standard form.

Calculations involving masses

Which of the following is the correct value for Avogadro's constant?

number of moles = (6.02 × 10²³) ÷ number of particles

number of moles = number of particles ÷ (6.02 × 10²³) 

number of moles = number of particles × (6.02 × 10²³) 

Which of the following correctly shows the relationship between the number of particles, number of moles and Avogadro's constant (6.02 × 10²³)?

There are {{}} moles in 5.42 × 10²³ particles of calcium carbonate. 
Give your answer to 3 significant figures.

Match the chemical formula to the correct type of particle.

Match the values that have an equivalent number of particles.

The mass of one atom of nickel is 9.75 × 10⁻²³ grams. 
What is the mass of 1.25 mol of nickel in grams?
Give your answer to 3 s.f. 

The relative atomic mass for this element is {{}}.

a substance made up of only one type of atom

two more or elements chemically bonded together

a particle with an electrical charge due to the gain/loss of electrons

a particle consisting of two or more atoms joined by covalent bonds

Match each keyword to the correct description.

Which of the following formulae are for substances that contain ionic bonds?

Which formulae indicate substances that are simple molecular in structure?

The chemical formula for sodium bromide is {{}}.

The relative formula mass of magnesium chloride, MgCl₂, is {{}}.

Starter Quiz

The relative atomic mass for this element is .