Reactants are the elements or compounds before a reaction takes place. Reactants are found on the left-hand side of a chemical equation.

Products are the elements or compounds that are formed after a reaction has taken place.  Products are found on the right-hand side of a chemical equation.

A particle model of chemical reactions

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

substances present before a chemical reaction has taken place.

substances formed after a chemical reaction has taken place.

In a chemical reaction, what happens to the atoms?

In the chemical equation 2H₂ + O₂ → 2H₂O, what are the reactants?

Which of the following is a characteristic of a chemical reaction?

Not enough information is known, so it cannot be determined.

Different reaction conditions would lead to different answers.

After the reaction 2H₂ + O₂ → 2H₂O, what happens to the total number of atoms?

In the equation 2Na + Cl₂ → 2NaCl, what is the simplest ratio of sodium (Na) atoms to chlorine (Cl) atoms in the reactants?

A metal sulfate contains the group of elements -SO₄, nitrates have the group -NO₃ and {{}} have the group -CO₃.

What elements are present in the calcium chloride?

What of the following is an example of a molecular element?

Match the reacting elements with the compound formed.

What indicates a compound in a chemical formula?

Starter Quiz