State the formula and valency of oxide ions.

Explanation:

Valency: An atom’s combining capacity is known as its valency. The valency of the element represents the number of bonds that an atom can form as part of a compound.

• An oxide is a category of chemical compound that has one or more oxygen atoms as well as another element in its composition.
• The Oxygen atom ${\mathrm{O}}_2$ has a total of 8 electrons, and the electronic configuration is 2, 6.
• The oxide ion ${{\mathrm{O}}_2}^{-2}$ will have 2 electrons more than the atomic configuration to attain a stable electronic configuration, i.e. 2,8.
• The formula of oxide is ${{\mathrm{O}}_2}^{-2}$ and valency is -2.