what is the valency of carbonate co₃^2-?

The valency of the carbonate ion (CO3²⁻) is 2. This is because the carbonate ion can combine with two hydrogen ions (or equivalent cations) due to its overall -2 charge, allowing it to form stable compounds like calcium carbonate (CaCO3) and sodium carbonate (Na2CO3).

• The valency of the whole carbonate ion refers to the number of bonds it can form to attach to other ions, which is 2, matching its negative charge.
• If you are asking about individual atom valencies: within the carbonate ion, the valency of carbon (C) is 4, as carbon forms one double bond and two single bonds with three oxygen atoms, fulfilling the octet rule.