why are two potassiums needed to bond to one carbonate?

Question

why are two potassiums needed to bond to one carbonate?

Answer 1

The carbonate anion is CO₃^2-, i.e. it has a minus 2 charge on it. Each potassium (K) ion has a plus 1 charge on it, i.e. it is represented as K⁺. In order for the compound potassium carbonate to be neutral (no net charge) it will take two K⁺ ions for each CO₃^2- ions. Thus, potassium carbonate is K₂CO₃.