Skip to content
CHEM 121 Studioby Learn4Less · UBC CHEM 121

CHEM 121 glossary

Octet rule

Atoms tend to bond until each is surrounded by 8 valence electrons (a noble-gas count); H needs only 2, the duet. Period-2 atoms (C, N, O, F) never exceed 8.

OCO
In O=C=O, every atom has an octet: each O has 2 bonds + 2 lone pairs, C has 4 bonds.

Example

In CHX4\ce{CH4}, C has 4 bonding pairs (8 e⁻) and each H has 1 bonding pair (2 e⁻). BFX3\ce{BF3} (6 e⁻ on B) and SFX6\ce{SF6} (12 e⁻ on S) are exceptions.