In a few cases, isotopes are different enough to earn different names. Normal hydrogen has no neutrons. Hydrogen 2 (one proton and one neutron) is called deuterium. Hydrogen 3 (one proton and two neutrons) is called tritium. All behave chemically as hydrogen. For example, deuterium combines with oxygen to make a form of water called heavy water, famous for its use in the manufacture of hydrogen bombs.
