Octet Definition

Chemistry Glossary Definition of Octet

This is a diagram of the valence electron of a neon atom, which has a complete octet.
This is a diagram of the valence electron of a neon atom, which has a complete octet. MEHAU KULYK / Getty Images

Octet Definition

In chemistry, an octet is a group of eight valence electrons surrounding an atom. All noble gases have an octet of valence electrons, with the exception of helium.