Cathode rays are streams of electrons. Compare with anode . The electrode at which reduction occurs. Compare with anion . A cation is a positively charged ion.
Metals typically form cations.
Compare with physical change . A chemical change is a dissociation, recombination, or rearrangement of atoms. A compound is a material formed from elements chemically combined in definite proportions by mass. For example, water is formed from chemically bound hydrogen and oxygen. Any pure water sample contains 2 g of hydrogen for every 16 g of oxygen.