Question #2f9a7

1 Answer
May 26, 2014

deuterium, symbol D, is an isotope of Hydrogen.

Hydrogen has three isotopes. Most hydrogen atoms have one proton and one electron and no neutrons, so have a mass number of 1. Deuterium atoms have 1 proton and 1 neutron in the nucleus, so a mass number of 2. They are chemically identical to hydrogen, but heavier.