Meaning & use
lone pair
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Meaning
nouncountablechemistryspecialist
A pair of electrons in an atom's outer shell that is not shared with another atom in a chemical bond.
Grammar: Countable: you can say 'a lone pair' or 'two lone pairs'. It often appears before another noun, as in 'lone pair electrons'.
Patterns
- a lone pair of electrons
- lone pair electrons
- have a lone pair
- donate a lone pair
Water has two lone pairs on the oxygen atom, which is why the molecule is bent.
In ammonia, the nitrogen atom has one lone pair that can accept a proton.
The Lewis structure shows three bonding pairs and one lone pair around the central atom.
Word forms
| plural | lone pairs |
|---|
Common combinations
- a lone pair of electrons
- A lone pair of electrons occupies more space than a bonding pair.
- lone pair electrons
- Lone pair electrons repel each other strongly.
- donate a lone pair
- The oxygen atom can donate a lone pair to a metal ion.
- the lone pair on the nitrogen
- The lone pair on the nitrogen makes the molecule basic.
Synonyms and how they differ
- nonbonding pair
- A more general term for any electron pair not used in bonding; 'lone pair' is the usual term in basic chemistry.
- unshared pair
- Similar meaning, but less common in modern textbooks; both describe electrons that belong to one atom only.
Opposites
Word family
Commonly confused: lone pair or bonding pair?
lone pair vs bonding pair
A bonding pair is shared between two atoms, while a lone pair belongs to just one atom.
Practice
In a water molecule, how many lone pairs are on the oxygen atom?
Choose one answer.
Oxygen in water has two lone pairs, which help give the molecule its bent shape. One lone pair would be true for ammonia, not water.
Make it your own
Write a sentence using “lone pair”, then check it and compare it with the examples above.