The formula of a covalent network or ionic compound gives the simplest ratio of atoms/ions in the substance. Sometimes the name of the compound gives information about the formula of that compound.

The general formula for a perovskite is ABO3 where A and B are cations. The easiest way to visualize the structure is in terms of the BO6 octahedra which share corners infinitely in all 3 dimensions, ...

The formula of an ionic compound can be deduced from the formulae of its ions. Remember that for the metal elements in groups 1, 2, and 3 the charge on the ion can be deduced by how many outer ...