Other combinations of atoms also exist, either larger ionic complexes or complete molecules. The three-dimensional structures are drawn as CPK models. CPK structures represent the atoms as spheres, where the radius of the sphere is equal to the van der Waals radius of the atom; these structures give an approximate volume of the polyatomic ion.
Polyatomic Ionic Compound Sulfuric Acid Many common chemicals are polyatomic compounds and contain polyatomic ions.
Many materials exist as simply binary compounds composed of a metal cation and a nonmetal anion, with each ion consisting of only one type of atom. The table below lists a number of polyatomic ions by name and by formula. For each polyatomic ion, the name, chemical formula, two-dimensional drawing, and three-dimensional representation are given.
Some of the most useful materials we work with contain polyatomic ions. Some names are simple - we know Romeo mainly as Romeo. Compounds formed from such ion combinations are called polyatomic ionic compounds, but the polyatomic ion behaves as a single unit.