Chemistry: A Molecular Approach (3rd Edition)

Final compound formed has the formula $K_{2}CO_{3}$.
The metal cation is $K^{+}$ The polyatomic anion is $CO_{3}^{2-}$ Combine 2 $K^{+}$ and 1 $CO_{3}^{2-}$ to balance the charge. Final compound formed has the formula $K_{2}CO_{3}$.