Explanation

Deuterium, (D, or 2H), also called heavy hydrogen.

Deuterium is an isotope of hydrogen.

In the simple hydrogen molecule, 

there is one proton,

one electron,

and no neutrons,protons,electrons,

and neutrons being the elementary particles that make up the atom.).

while 

Deuterium, on the other hand, is composed of one proton, one electron, and one neutron.

ND11-07-2023