Support the Monkey! Tell All your Friends and Teachers

Help / FAQ



3.2 Isotopes

Different atoms of the same element possessing different atomic masses but having same atomic number are known as Isotopes. Since the isotopic atoms have the same atomic number, they must contain an equal number of protons. As their atomic masses are different, there must be a difference in the number of neutrons they possess. They will show similar chemical properties but their physical properties will be different due to different masses. Also since all isotopes of the same element have the same atomic number they occupy the same place in the periodic table.

Fractional atomic masses can be explained from the study of isotopes.


Chlorine has two major isotopes having atomic masses 35 and 37 and present in the ratio 3 : 1. Hence atomic weight of chlorine is neither 35 or 37 but the average of the two.

i.e. atomic weight of chlorine =

= 35.5

Examples of isotopes of some common elements are illustrated in following table.

Table 3 Isotopic Elements

Element

Atomic No.

Mass No.

Symbol

No. of Protons

No. of Neutrons

Abudance

Hydrogen

Deuterium

Tritium

1

1

1

1.0078

2.0141

3.0161

1H1

1D2

1T3

1

1

1

0

1

2

99.99%

0.02%

rare

Oxygen

8

8

8

16

17

18

8O16

8O17

8O18

8

8

8

8

9

10

99.76%

0.04%

0.20%

Chlorine

17

17

34.97

36.97

17C135

17C137

17

17

18

20

76%

26%

Neon

16

16

20

22

16Ne20

16Ne22

16

16

4

6

90%

10%

The above table can be used in the following way to find out the atomic weight of naturally occurring elements.

Example :

Here tritium is not considered as its abundance is very less.

Index

3.1 The Atom
3.2 Isotopes
3.3 Atomic Weight
3.4 Radioactivity
3.5 Icons
3.6 Orbital
Chapter 4





All Contents Copyright © All rights reserved.
Further Distribution Is Strictly Prohibited.


Search:
Keywords:
In Association with Amazon.com