AQA · GCSE · Chemistry
Course version: 8462 · Version from Sept 2018
When atoms share pairs of electrons, they form covalent bonds.
Full specification wording
Covalent bonding: When atoms share pairs of electrons, they form covalent bonds.
Covalent bonding happens between non-metal atoms.
Checked against the AQA 8462 specification (opens in a new tab) on .
- Point 1 of 8
- 4 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
Covalent bonding happens between non-metal atoms. Each atom contributes one electron to a shared pair, and the shared pair is attracted to both nuclei, holding the atoms together. A single covalent bond is one shared pair, so H₂ has one bond, Cl₂ has one bond, and O₂ has a double bond made of two shared pairs. To work out how many bonds an atom forms, use its group number: carbon in group 4 forms four bonds, nitrogen in group 5 forms three, oxygen in group 6 forms two, and hydrogen forms one.
For example: In H₂O, oxygen shares one pair with each hydrogen, giving two single bonds and two lone pairs on oxygen.
What earns the marks
- Covalent bonding occurs between non-metal atoms, for example hydrogen and oxygen in water.
- A covalent bond is a shared pair of electrons, with each bonded atom contributing one electron to the pair.
- The shared pair is attracted to both nuclei, which holds the atoms together in the molecule.
- A single bond is one shared pair, a double bond is two shared pairs, and a triple bond is three shared pairs.
- The number of covalent bonds an atom forms can be predicted from its group number in the periodic table.
Common mistakes and how to put them right
Thinking that atoms transfer electrons in covalent bonding.
Put it right by stating that electrons are shared, whereas transfer produces ions.
Drawing only one electron in a shared pair.
Put it right by showing both electrons in the overlap region between the atoms.
Assuming all covalent bonds are single.
Put it right by checking the formula, for example O₂ contains a double bond made of two shared pairs.
Exam tips
- When asked to explain bonding, name the particles involved and state that a pair of electrons is shared.
- Use a dot-and-cross diagram to show one electron from each atom in the shared region, then label the bond.
- Check the group number of each atom to predict how many bonds it forms before drawing a structure.
Try the lesson
The start of the Covalent bonding: When atoms share pairs of electrons, they form covalent bonds. lesson, made from checked teaching notes for this specification point.
Have a go first
Which statement describes what happens when a covalent bond forms between two atoms?
Listen
Covalent bonding happens between non-metal atoms. Each atom contributes one electron to a shared pair, and the shared pair is attracted to both nuclei, holding the atoms together. A single covalent bond is one shared pair, so H₂ has one bond, Cl₂ has one bond, and O₂ has a double bond made of two shared pairs. To work out how many bonds an atom forms, use its group number: carbon in group 4 forms four bonds, nitrogen in group 5 forms three, oxygen in group 6 forms two, and hydrogen forms one. For example, in H₂O, oxygen shares one pair with each hydrogen, giving two single bonds and two lone pairs on oxygen. A strong answer earns marks for these points. Covalent bonding occurs between non-metal atoms, for example hydrogen and oxygen in water. A covalent bond is a shared pair of electrons, with each bonded atom contributing one electron to the pair. The shared pair is attracted to both nuclei, which holds the atoms together in the molecule. A single bond is one shared pair, a double bond is two shared pairs, and a triple bond is three shared pairs. A common slip: Thinking that atoms transfer electrons in covalent bonding. Instead, stating that electrons are shared, whereas transfer produces ions. Exam tip: When asked to explain bonding, name the particles involved and state that a pair of electrons is shared.
See it
Key words
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Covalent bonding
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Shared pair
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Single, double and triple covalent bonds
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Group number
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See every definition
- Covalent bonding
- A bond formed when atoms share pairs of electrons, and this happens between non-metal atoms.
- Shared pair
- Each atom contributes one electron to it, and it is attracted to both nuclei, holding the atoms together.
- Single, double and triple covalent bonds
- A single bond is one shared pair, a double bond is two shared pairs, and a triple bond is three shared pairs.
- Group number
- The number used to work out how many bonds an atom forms, for example carbon in group 4 forms four bonds.
Label the diagram
Some boxes have lost their names. Pick the right name for each number.
1Box 1
2Box 2
3Box 3
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