Isotopes of hydrogen

Introduction

In chemistry, an isotope is the different form of the same element, which has the same atomic number but the different mass numbers. Naturally occurring hydrogen and its compounds are composed of 3 isotopes. The most abundant of the 3 isotopes is protium, commonly referred to as hydrogen. Protium(H-1) and Deuterium(H-2) account for approximately 99.98%, and the remaining 0.02% is tritium(H-3). The table below summarizes the three isotopes of hydrogen.

 

Name of isotope

Symbol

Mass number

Relative abundance

Nature

Protium/hydrogen

H

1

99.985%

Non-radioactive

Deuterium

D

2

0.015%

Non-radioactive

tritium

T

3

10-15

Radioactive

 

 

 

 

 

 Physical properties of the three isotopes of hydrogen:

isotope

Molecular mass

Melting point in K

Boiling point in K

Heat of fusion

Heat of vaporization

H2

2.016

13.8

20.4

0.117

0.994

D2

4.028

18.7

23.9

0.197

1.126

T2

6.03

20.63

25.0

0.250

1.393

 

 

Isotopic effects:

Generally, all three isotopes of hydrogen have identical chemical properties. However, there is still a slight quantitative variation exist within. For instance, the rate of reaction between chlorine and hydrogen is approximately 13 times faster than the rate of reaction between hydrogen and bromine under similar conditions. The isotopic difference, therefore, refers to the difference in the chemical properties as a result of a change in the mass number of isotopes of hydrogen.

Write the names of isotopes of hydrogen. What is the ratio of these isotopes?

Answer: There are three isotopes of hydrogen; namely, protium, deuterium, and tritium. Their ratios are: protium: deuterium: tritium= 1:2:3



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