64. How do the isotopes of hydrogen differ from each other in their properties? In what physical properties do hydrogen and deuterium differ?

The electronic configuration of all the isotopes of hydrogen is same, therefore, chemical properties of all the isotopes are identical. However, they differ from each other in their rates of reaction and equilibrium constants for reversible reactions e.g. protium reacts with chlorine 13.4 times as fast as deuterium does.

Due to the difference in the masses of the isotopes of hydrogen, they have different physical properties. Property differences arising from differences in mass are called isotopic effects.

Properties: The difference in the masses of protium and deuterium produce appreciable changes in many of their physical properties like melting point and boiling point, latent heat of fusion, evaporation, sublimation etc. As deuterium is heavier than hydrogen, so the rates of a reaction involving deuterium are slower than reactions involving hydrogen. For the same reason, D₂ has a higher boiling point than that of H₂.