Question

Name the isotopes of hydrogen. Write their atomic composition schematically and explain which of these is radioactive ?

Answer 1

1. Hydrogen has three isotopes i.e., hydrogen \(\left({ }_{1}^{1} \mathrm{H}\right)\), deuterium \(\left({ }_{1}^{2} \mathrm{H}\right)\) and tritium \(\left({ }_{1}^{3} \mathrm{H}\right)\) with mass numbers 1, 2 and 3 respectively.
2. They all contain one proton and one electron but different number of neutrons in the nucleus.
3. Atomic composition of isotopes of hydrogen:

   Name of the isotope	Symbol	Atomic number Z	Atomic mass number A	Neutron number N	Abundance	Stability
   Hydrogen	\[\ce{H  or _1^1H or H-1}\]	1	1	0	99.98%	Stable
   Deuterium	\[\ce{D  or _1^2H or H-2}\]	1	2	1	0.015%	Stable
   Tritium	\[\ce{T  or _1^3H or H-3}\]	1	3	2	Trace	Radioactive

4. Tritium is a radioactive nuclide with a half-life period of 12.4 years and emits low energy β particles.
5. Schematic representation of isotopes of hydrogen is as follows:
6.