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Chemical Formula

Chemistry: AQA GCSE Higher, topic 1.1.2

Compounds

Atoms of different elements can be combined together to create compounds. Compounds have formulae that are made by combining the chemical symbols of the elements that combine to make them.

Different compounds

Different compounds

  • Combining different atoms creates different compounds. There are a lot of combinations that can be created.
  • A compound is made up of at least 2 different elements.
Lego

Lego

  • Compounds are a bit like Lego.
  • Different combinations of bricks result in different models.
  • Similarly, different combinations of atoms result in different compounds.
E.g. sodium oxide

E.g. sodium oxide

  • Combining sodium (Na) atoms and oxygen (O) atoms gives sodium oxide.
  • We can represent this compound by combining the chemical symbols of the 2 elements (Na and O) to create the chemical formula Na2O.

Test yourself on Chemical Formula

  • What is the chemical formula for sodium oxide?

  • Select the true statement in each pair.

  • Why can atoms of different elements form such a huge number of different compounds?

  • Sodium oxide has the formula Na2O. How many different elements are chemically combined in sodium oxide?

  • Every element has its own unique chemical symbol. Why does this let a compound's formula show which elements it contains?

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