The three stable isotopes of neon: \[{}_{10}^{20}Ne\], \[{}_{10}^{21}Ne\]and \[{}_{10}^{22}Ne\]have respective abundances of 90.51%, 0.27% and 9.22%. The atomic masses of the three isotopes are 19.99 u, 20.99 u and 21.99 u, respectively. Obtain the average atomic mass of neon.

3 years ago

Answer –

Mass of neon isotope – \[{}_{10}^{20}Ne\], m₁ = 19.99 u

Abundance of neon isotope – \[{}_{10}^{20}Ne\], n₁ = 90.51%

Mass of neon isotope – \[{}_{10}^{21}Ne\], m₂ = 20.99 u

Abundance of neon isotope – \[{}_{10}^{21}Ne\], n₂ = 0.27%

Mass of neon isotope – \[{}_{10}^{22}Ne\], m₃ = 21.99 u

Abundance of neon isotope – \[{}_{10}^{22}Ne\], n₃ = 9.22%

Average atomic mass of Neon is given by the relation –

\[m=\frac{{{\operatorname{m}}_{1}}{{n}_{1}}+{{m}_{2}}{{n}_{2}}+{{m}_{3}}{{n}_{3}}}{{{n}_{1}}+{{n}_{2}}+{{n}_{3}}}\]

\[m=\frac{19.99\times 90.51+20.99\times 0.27+21.99\times 9.22}{90.51+0.27+9.22}\]

\[m=20.1771u\]