valency

Valency is a measure of how many electrons an atom can gain, lose, or share to form chemical bonds with other atoms. It reflects an atom's ability to combine with others to become stable. For example, oxygen has a valency of two because it typically needs to gain or share two electrons to complete its outer shell. Understanding valency helps explain how different elements connect to form molecules, shaping the structure and properties of substances. It’s a fundamental concept in chemistry that describes an atom's bonding capacity in chemical reactions.