2.0 Atomic and Physical Properties of Hydrogen (reference: NCERT)

Property

Hydrogen

Deuterium

Tritium

Relative abundance $\% $

99.985

0.0156

10–15

Relative atomic mass ($g mol^{–1}$)

1.008

2.014

3.016

Melting point / $K$

13.96

18.73

20.62

Boiling point/ $K$

20.39

23.67

25.0

Density / $gL^{–1}$

0.09

0.18

0.27

Enthalpy of fusion/$kJ mol^{–1}$

0.117

0.197

-

Enthalpy of vaporization/$kJ mol^{–1}$

0.904

1.226

-

Enthalpy of bond dissociation/$kJ mol^{–1}$ at $298.2\ K$

435.88

443.35

-

Internuclear distance/$pm$

74.14

74.14

-

Ionization enthalpy/$kJ mol^{–1}$

1312

-

-

Electron gain enthalpy/$kJ mol^{–1}$

–73

-

-

Covalent radius/$pm$

37

-

-

Ionic radius $(H^{–})$$/$$pm$

208