How can chlorine have an atomic mass of #35.45*"amu"#?

1 Answer
Mar 7, 2017

Answer:

The atomic mass quoted on the Periodic Table is simply the WEIGHTED average of the individual isotopic masses of an element.

Explanation:

We can calculate the average atomic mass of the element chlorine, given that its isotopic distribution is: #""^35Cl, 75.53%; ""^37Cl, 24.47%#.

And the weighted average of the masses is:

#(0.7553xx35+0.2447xx37)*"amu"#

#=# #35.46*"amu"#, which is very near the atomic mass quoted on the Periodic Table (they are slightly different because the Table considers minor isotopes).