Write Lewis structures for these ions. Show all valence electrons and all formal charges. (Q) Carbonate ion, CO32-

Lewis structure represents the systematic arrangement of atoms around the central atom. Electrons in this structure are indicated by dots. The central atom is the least electronegative element in a compound.

The molecular formula of the given compound is ${{\mathrm{CO}}_3}^{2-}$. O is more electronegative than C. Therefore, C is the central atom in the compound  

The C atom has 4 valence electrons and O has 6 valence electrons. Calculate the total number of valence electrons.

$\begin{array}{rcl}\mathrm{Total} \mathrm{number} \mathrm{of} \mathrm{valence} \mathrm{electrons}& =& 4+\left(6\times 3\right)+2\\ & =& 24\end{array}$

The total number of valence electrons in ${{\mathrm{CO}}_3}^{2-}$are 24. The number of valence electron pairs is half of the total number of valence electrons. Therefore, the number of valence electron pairs 12, which is 24/2.