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Chemical Formula - GCSE Chemistry Definition

Reviewed by: Philippa Platt

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A chemical formula is a concise way of representing the elements that make up a compound and the ratio in which these elements combine. In GCSE Chemistry, understanding chemical formulas is essential, as they provide vital information about the composition of substances at the molecular level.

Each chemical symbol in a formula stands for an element from the Periodic Table, and subscript numbers indicate how many atoms of each element are present in the compound.

For example:

  • H2O represents water, with two hydrogen atoms and one oxygen atom.

  • CH4 represents methane, with for hydrogen atoms and one carbon atom.

Understanding chemical formulas helps students predict the properties of a substance and how it will react with others.

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Philippa Platt

Reviewer: Philippa Platt

Expertise: Chemistry Content Creator

Philippa has worked as a GCSE and A level chemistry teacher and tutor for over thirteen years. She studied chemistry and sport science at Loughborough University graduating in 2007 having also completed her PGCE in science. Throughout her time as a teacher she was incharge of a boarding house for five years and coached many teams in a variety of sports. When not producing resources with the chemistry team, Philippa enjoys being active outside with her young family and is a very keen gardener

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