Lesson 3 of 8
Word equations
Goal: Write word equations for reactions.
A word equation is a short way to write down a reaction. The reactants go on the left and the products go on the right.
magnesium + oxygenreactants: what you start with
→magnesium oxideproduct: what is made
- The arrow means “react to make”. It is not an equals sign.
- The + means “and”. It goes between two reactants, or between two products.
- Only substances go in. Heat, light and flames are not substances, so leave them out.
- Names give clues. When a metal reacts with oxygen, the product is a metal oxide.
Symbol equations use formulae in place of names: 2Mg + O2 → 2MgO. The numbers in front make it balance: there are 2 magnesium atoms and 2 oxygen atoms on each side.
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Key words in this lesson
Reactant A substance you start with in a reaction
Product A new substance made in a reaction
Word equation Shows a reaction using the names of the substances
Oxide A compound of an element joined with oxygen