Final answer:
The carbonate anion, CO₃²⁻, is a polyatomic ion with a trigonal planar electron-pair geometry and a linear molecular structure. It can exist in multiple resonance forms, with the actual structure being an average of these forms.
Step-by-step explanation:
The carbonate anion, CO₃²⁻, is a polyatomic ion that consists of a carbon atom bonded to three oxygen atoms. It has a trigonal planar electron-pair geometry and a linear molecular structure.
The electron-pair geometry refers to the arrangement of electron pairs around the central atom, while the molecular structure describes the geometric arrangement of the atoms in the molecule.
The carbonate ion can exist in multiple resonance forms, which are different representations of the same molecule. In the resonance hybrid, the electrons are shared between the carbon and all three oxygen atoms, resulting in one and one-third covalent bonds between them. The actual structure of the carbonate ion is an average of these resonance forms.