Words become formulae

The idea

A chemical equation represents a chemical reaction using chemical formulae instead of words, which makes it more concise and useful than a word-equation.

Too many words

"Magnesium + Oxygen → Magnesium oxide" takes five words and a lot of space. Every reaction in a book would need many such lines.

How could we write it in much less space?

• Use the formula of each substance instead of its name
• Write only the first letters, like M + O → M
• Draw a picture each time

Names → formulae

Tap a formula tile, then the box under the name it stands for.

Formulae make it concise

A chemical equation represents a chemical reaction using chemical formulae instead of words. This makes it more concise and more useful than a word-equation.

The small number is part of the formula: O₂ means two oxygen atoms joined together.

• Word-equation | Chemical equation
• Magnesium + Oxygen → Magnesium oxide | Mg + O₂ → MgO
• Zinc + Sulphuric acid → Zinc sulphate + Hydrogen | Zn + H₂SO₄ → ZnSO₄ + H₂

Notes

A chemical equation represents a chemical reaction using chemical formulae instead of words, which makes it more concise and useful than a word-equation.

Check yourself

Which one is a chemical equation (not a word-equation)?

Why are formulae better than words in an equation?

How many formulae are written on the RHS of Zn + H₂SO₄ → ZnSO₄ + H₂ ?

Answer: 2

ZnSO₄ and H₂: two products.

• Zinc + Sulphuric acid → Zinc sulphate + Hydrogen. This one is written in words: a word-equation.
• Zn + H₂SO₄ → ZnSO₄ + H₂ — correct. Yes! It uses formulae instead of words.
• Zinc and acid make a salt and a gas. This is an ordinary sentence, not an equation.
• Words are not allowed in science. Word-equations are fine: they come first. Formulae are simply shorter.
• They make the reaction faster. Writing does not change how fast a reaction happens!
• They are more concise and more useful — correct. Yes! Short, and they show which atoms are present.