Elements & Compounds (WJEC GCSE Science (Double Award)): Revision Note

Elements Definition

• In chemistry, elements are substances that are made up of only one type of atom

• The chemical elements are listed in the Periodic Table

A simple Periodic Table

The Periodic Table lists all chemical elements

• Elements can be grouped into two categories:

  • Atoms - made from single particles

  • Molecules - made from more than one particle chemically joined together

Examples of elements

Elements contain only one type of atom and exist as atoms or molecules

• Elements cannot be broken down into simpler substances by chemical means

  • But, they can be reacted together to make more complex substances

• Elements are, therefore, considered to be the basic building blocks of all substances

Compounds Definition

• Elements take part in chemical reactions, where the atoms rearrange to form compounds

  • The properties of compounds can be quite different from the elements that form them

Elements into compounds diagram

The properties of sodium chloride are quite different from sodium and chlorine

• Compounds are substances that are made of two or more different types of atom that are chemically joined 

  • This means that compounds are also molecules

Examples of compounds

Compounds are molecules that contain two or more different types of atoms chemically joined together