Exceptions to the Octet Rule

Definition

The octet rule states that elements usually combine in such a way that they each have eight electrons in their valence shell, giving them the same electronic configuration as a noble gas. However, there are exceptions to this rule for molecules and ions that do not follow this rule.

Related terms

Octet Rule:

A chemical rule of thumb that reflects observation that atoms of main-group elements tend to combine in such a way that each atom has eight electrons in its valence shell.

Valence Electrons:

These are the outermost electrons on an atom and can participate in forming bonds with other atoms.

Noble Gases:

These are any group 18 element on the periodic table which all have full electron shells.