Isotopes Of Hydrogen
Hydrogen of Class 11
Isotopes Of Hydrogen
It has been found by mass spectrograph that hydrogen has three isotopes namely; Protium, Deuterium and Tritium. The relative abundance of three isotopes of hydrogen is as under
(a) Protium or hydrogen
It is represented by the symbol H. Its atomic number is 1 and mass number is also 1. It has one proton (but no neutron) in its nucleus and one electron in its 1s orbital. Naturally occurring hydrogen contains 99.985% of this isotopes.
(b) Deuterium or heavy hydrogen
It is represented by the symbol D or 
. It’s atomic number is 1 and mass number is 2. It has one proton and one neutron in its nucleus and one electron in its 1s orbital. Naturally occurring hydrogen has 0.015% of this isotopes mostly in the form of HD.
(c) Tritium
It is represented by the symbol T or 
. Its nucleus has one proton and two neutrons and there is one electron in its 1s orbital. It is an extremely rare isotope. Out of 1017 molecules of ordinary hydrogen there is just one molecule of tritium. This isotope of hydrogen is radioactive in nature and emits low energy β - particles (t1/2 = 12.33γ)
It may be noted that three isotopes of hydrogen have same chemical properties because of the same electronic configuration 1s1. However due to different mass numbers they have different rates of chemical reactions. For example, reaction between protium and chlorine is 13.4 times faster than that between deuterium and chlorine. Similarly electrolysis of ordinary water (H2O) occurs more rapidly than of heavy water(D2O).Difference in properties arising due to the difference in mass number is referred to as isotopic effect.
Uses of Tritium
Tritium is used to make thermonuclear devices and for carrying out researches in fusion reactions as a means of producing energy. Tritium gas is usually stored by making UT3, which on heating to 673 K releases T.
