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This lesson covers covalent bonding, the second major type of chemical bonding in the AQA GCSE Chemistry specification (4.2.2). Covalent bonding occurs between non-metal atoms and involves the sharing of electron pairs. You need to understand how covalent bonds form, be able to draw dot-and-cross diagrams for key molecules, and recognise single, double, and triple bonds.
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 both atoms count the shared pair as part of their outer shell. This allows both atoms to achieve a full outer shell of electrons.
The shared pair of electrons is attracted to the nuclei of both atoms — this electrostatic attraction holds the atoms together.
Exam Tip: The definition of a covalent bond is: "A shared pair of electrons between two atoms." You must say "shared pair" not just "shared electrons." If you say "the atoms share electrons" without specifying "a pair," you may not get the mark.
Covalent bonds form because:
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