Question

The three stable isotopes of neon : `._(10)^(20)Ne, ._(10)^(21)Ne` and `._(10)^(22)Ne` have respective abundance of 90.51%, 0.27% and 9.22%. The atomic masses of the three isotopes are 19.99u, 20.99 u and 21.99 u, respectively. Obtain the average atomic mass of Neon.

Answer 1

The masses of three isotopes are 19.99 u, 20.99 u, 21.99 u
Their relative abundances are 90.51 %, 10.27% and 9.22%
`therefore` Average atomic mass of Neon is
`m = (90.51xx19.99+0.27xx20.99+9.22xx21.99)/((90.51+0.27+9.22))`
`=(1809.29+5.67+202.75)/(100)=(2017.7)/(100)=20.17 u`