Neon has three naturally occurring isotopes. They include Ne-20, atomic mass of 19.992 amu and percent abundance of 90.48%; Ne-21, atomic mass of 20.994 amu and percent abundance of 0.27%; Ne-22 has a mass of 21.991 amu and percent abundance of 9.25%. Calculate the average atomic mass of neon?

The three isotopes of neon are Ne-20 with atomic mass 19.992 amu and % abundance 90.48%, Ne-21 with atomic mass 20.994 amu and % abundance 0.27% and Ne-22 with atomic mass 21.991 amu and % abundance 9.25%.

The average atomic mass of Ne can be calculated as follows:

M=M (Ne-20) * % (Ne-20) + M (Ne-21) * % (Ne-21) + M (Ne-22) * % (Ne-22)

On putting the values,

M = (19.992 amu) (0.9048) + (20.994 amu) (0.0027) + (21.991 amu) (0.0925) = 20.180 amu

Thus, average mass of neon is 20.180 amu