Covalent Bonding

This lesson covers covalent bonding as required by the AQA GCSE Combined Science Trilogy specification (8464), section 4.2.2. You need to understand how covalent bonds form, draw dot-and-cross diagrams for simple molecules, and recognise single and double covalent bonds.

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What Is Covalent Bonding?

A covalent bond is a shared pair of electrons between two atoms. Covalent bonding occurs between non-metal atoms. Each atom contributes one electron to the shared pair, and the shared electrons are attracted to the nuclei of both atoms, holding them together.

Covalent bonding happens because non-metal atoms need to gain electrons to achieve a full outer shell, but neither atom is willing to give up electrons completely (as metals do in ionic bonding). Instead, they share electron pairs.

Exam Tip (AQA 8464): The definition of a covalent bond is "a shared pair of electrons between two atoms." Make sure you say "shared pair" — a single electron is not a covalent bond.

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How Covalent Bonds Form