Isotopes of hydrogen

Hydrogen is the most abundant element in the universe. About half the mass of sun and stars is due to hydrogen. Jupiter and Saturn planets consist mainly of hydrogen. It is common on earth in water, coal, petroleum, clay, animal and vegetable matter that constitutes 0.9% by weight of Earth's crust. It is the ninth element in order of abundance.

Isotopes of hydrogen

Isotopes are the different forms of the same element, which have the same atomic number but different mass numbers. The isotopes of hydrogen are protium, deuterium and tritium with mass number 1, 2 and 3 respectively. The relative abundance of three isotopes in nature is in the ratio of 1 : 1.5 x 10^-2: 1 x 10^-17respectively. The hydrogen occurring in nature is mainly composed of atoms of protium and it contains only 0.015% of deuterium atoms. The third isotope of hydrogen is radioactive.

All the three isotopes of hydrogen have one electron in their only shell and one proton in the nucleus. However, they differ with respect to the number of neutrons in them.

It is the most abundant isotope of hydrogen. Its nucleus has one proton and no neutron (mass number = 1). It is represented as H.

It is present in heavy water (D₂O) and can be recovered by fractional electrolysis. Its nucleus has one proton and one neutron (mass number = 2). It is represented as D.

Tritium

It is the rarest isotope of hydrogen (10^-15%) due to the instability and radioactive nature of its nucleus. Its nucleus has one proton and two neutrons (mass number = 3). It is represented as T. It is prepared artificially, by the bombardment of nitrogen and an isotope of lithium with deutrons.