Question

The element lead (pb) consists of four naturally occurring isotopes with atomic masses 203.97302,205.97444,206.97587, n 207.97663 amu. the relative abundances of these four isotopes are 1.4,24.1,22.1, and 52.4 %, respectively. write the most common isotope of lead in two ways

Answer 1

The method of determining the most common isotope of lead is by determining the average atomic mass. The formula for determining the average atomic mass is:

`average atomic mass = \Sigma {percent abundance}* {atomic mass}`

Substituting the values in the formula:

`average atomic mass = \frac{{203.97302}* {1.4}+{205.9744}* {24.1}+{206.97587}* {22.1}+{207.97663}* {52.4}}{100}`

`average atomic mass = (285.562228+4963.984004+4574.166727+10897.975412)/(100)`

`average atomic mass = (20721.688371)/(100) = 207.22 amu`

The most common isotope of lead is:

Lead - 207.22 amu

The atomic symbol of lead is
`Pb`. The atomic number of
`Pb` is 82.

So, the the most common isotope of lead can be written as:

`_(207.22)^(82)Pb` and Lead - 207.22 amu.