One or two letters used to represent a chemical element. The first letter is always a capital letter, e.g. Br represents bromine.

A representation of either the number of atoms or ratio of atoms of each element in a substance, e.g. H₂O is water = 2 x hydrogen + 1 x oxygen

Chemical formulae

Science

In the Patterns in the periodic table unit, pupils will build on this knowledge to learn how the chemical and physical properties of different elements are indicated by their position on the periodic table and about key groups of elements. 

In the Solutions unit, pupils learnt about mixtures, solutions and dissolving in terms of the particle model.

Atoms, elements and compounds

Two hydrogen molecules and one oxygen molecule.

What does the chemical formula H₂O represent?

The compound is twice as heavy as oxygen.

In the formula CO₂, what does the subscript '2' indicate?

It is important to write subscript values correctly, both in terms of the value, but also in their physical size and placement to accurately represent the correct number of each type of ...

There's no difference. They have the same number of oxygen and hydrogen atoms.

What is the difference between H₂O and H₂O₂?

A graphical representation of a molecule.

A symbolic way to represent the elements in a chemical substance.

A method to determine the pH of a substance.

Which statement best defines a chemical formula?

Match the following chemical substances up to the key terms.

Which element does the chemical symbol 'O' represent?

In the chemical formula CO₂, what element does 'C' represent?

Match the chemical formula to the correct substance.

Each {{}} is represented by its own chemical symbol, for example 'K', 'Fe' or 'C'.

A substance that cannot be broken down into simpler substances.

Anything that has mass and takes up space.

A substance composed of only one chemical substance.

Two or more atoms bonded together (usually non-metals).

Two or more different types of atoms bonded together.

Match each term with its correct definition.

Starter Quiz