·adj Having a valence of four; tetratomic; quadrivalent.
tetravalent
[?t?tr?'ve?l(?)nt]
¦ adjective Chemistry having a valency of four.
divalent
[d??'ve?l(?)nt]
¦ adjective Chemistry having a valency of two.
Wikipedia
Valence (chemistry)
In chemistry, the valence (US spelling) or valency (British spelling) of an element is the measure of its combining capacity with other atoms when it forms chemical compounds or molecules.