The carbonate ion, CO32−, has a trigonal planar shape. In this ion, the carbon atom is at the center, and it is bonded to three oxygen atoms. These bonds form equal angles of approximately 120 degrees with each other.
This planar arrangement arises due to the sp2 hybridization of the carbon atom, which allows for the formation of three equivalent bonds using one s orbital and two p orbitals. The presence of resonance in the carbonate ion also contributes to its stability: the negative charges are delocalized over the oxygen atoms, making the shape and bond lengths more uniform.
In summary, the carbonate ion’s trigonal planar geometry results from its bonding and hybridization characteristics, which facilitate a stable and evenly distributed electron configuration.