Lewis structure — Science definition
A diagram that shows an atom's or molecule's valence electrons as dots and each bonding pair as a line.
Where it is taught
- Covalent Bonding — Bonding, Formulas & Molecular Structure, Physical Science: Chemistry, Grade 11
In use
The Lewis structure of water, for instance, shows two O–H bonding pairs and two lone pairs resting on the oxygen.
Covalent Bonding
Questions using lewis structure
Problem 1
In the Lewis structure of carbon dioxide (O=C=O), how many lone pairs are on each oxygen atom?
- 1
- 2
- 3
- 0
Answer and explanation
2
Each oxygen shares 2 pairs in its double bond and keeps 2 lone pairs of its own, completing its octet.
Problem 2
In the Lewis structure of a water molecule (H₂O), how many lone pairs are on the central oxygen atom?
- 4
- 0
- 1
- 2
Answer and explanation
2
Oxygen has 6 valence electrons; 2 are used in the two O–H bonds, leaving 4 electrons — that is 2 lone pairs.