# What is the geometry of the carbonate dianion, CO_3^(2-)?

May 2, 2017

We have $4 + 3 \times 6 + 2 = 24 \cdot \text{electrons}$ to distribute around 3 oxygen and 1 carbon atoms.......
A Lewis structure gives $O = C {\left(- {O}^{-}\right)}_{2}$, which gives one neutral ($s {p}^{2} - \text{hybridized}$) oxygen, and 2 formally anionic oxygen centres ($s {p}^{3} - \text{hybridized}$)......The central carbon is $s {p}^{2} - \text{hybridized}$.
If we ignore the $\pi - \text{bond}$, there are THREE regions of electron density around the central carbon, and trigonal planar geometry is adopted, with $\angle O - C - O = {120}^{\circ}$.