Valency, in chemistry, refers to the measure of the capacity of an atom to combine with other atoms. It is determined by the number of chemical bonds an atom can form.

Here are a few key aspects of valency:

• Combining Capacity: It represents the number of hydrogen atoms or other univalent atoms (atoms that form only one bond) that an atom can combine with.
• Determined by Electrons: Valency is related to the number of electrons in the outermost shell (valence shell) of an atom. Atoms tend to gain, lose, or share electrons to achieve a stable electron configuration, typically with eight electrons in their valence shell (octet rule).
• Variable Valency: Some elements can exhibit variable valency, meaning they can form different numbers of bonds depending on the chemical environment. Transition metals are particularly known for this.
• Examples:
  • Hydrogen (H) has a valency of 1.
  • Oxygen (O) has a valency of 2.
  • Nitrogen (N) often has a valency of 3.
  • Carbon (C) typically has a valency of 4.

For more detailed information, you can refer to these resources:

• Britannica - Valency
• LibreTexts - Valence Bond Theory