Question

How do you find the nature of abundance in :

hydrogen-2

helium-3

helium5

lithium-6

lithium-7

oxygen-16

oxygen-17

oxygen-18

neon-20

neon-23

Answer 1

Steps to find the natural abundance of isotopes:

Identify the atomic weights

Set abundance equal to x

Write out equation

Solve for x

a) hydrogen-2

Atomic weight of hydrogen = 1.00784 u

let isotopic abundance = x

equation : 1.00784 = 1.00784x + 2(1 - x)

x = 0.015

b)

helium-3

Atomic weight of helium = 3.016029 u

let isotopic abundance = x

equation : 4.002603 = 3.016029x + 4(1 - x)

x = 0.000137

c) helium 5

Atomic weight of helium = 4.002603 u

let isotopic abundance = x

equation : 4.002603 = 4.002603x + 3.016029(1 - x)

x = 99.99863

d) lithium 6

Atomic weight of lithium = 6.015122 u

let isotopic abundance = x

equation : 6.015122 = 6.015122x + 7(1 - x)

x = 7.59

e) lithium 7

Atomic weight of lithium =7.016004 u

let isotopic abundance = x

equation : 7.016004 =7.016004 x + 6.015122(1 - x)

x = 92.41

f) oxygen 16

Atomic weight of oxygen =15.9949 u

let isotopic abundance = x

equation : 15.9949=15.9949 x + 16(1 - x)

x = 99.757

similarly for others can be done....