Potassium forms an ionic compound with sulfur.
describe what happens when two atoms of potassium react with one atom of sulfur.
give your answer in terms of electron transfer.
give the formulae of the ions formed.

Balanced chemical reaction: 2K + S → K₂S, product of reaction is potassium sulfide.
There are same number of atoms on both side of chemical reaction, two potassium atoms and one sulfur atom.
Potassium oxidizes from zero to +1 oxidation number and sulfur is reduced from zero to -2 (gain two electrons).