Question

In naturally occurring neon, the fractional abundance of different isotopes is as follows: ²0Ne 0.9051; ²¹N 0.0027; ²³Ne 0.0922 What is the atomic mass of neon?

Answer 1

Answer: The atomic mass of neon comes out to be 20.2793 units.

Explanation:

Average atomic mass of an element is the sum of masses of all the isotopes each multiplied with its natural fractional abundance.

Formula that is used to calculate the average atomic mass follows:

$\text{Average atomic mass }=\sum_{i=1}^n\text{(Atomic mass of an isotopes)}_i\times \text{(Fractional abundance})_i$

We are given:

Mass of isotope 1 = 20 u

Fractional abundance of isotope 1 = 0.9051

Mass of isotope 2 = 21 u

Fractional abundance of isotope 2 = 0.0027

Mass of isotope 3 = 23 u

Fractional abundance of isotope 3 = 0.0922

Putting values in above equation, we get:

$\text{Average atomic mass of neon}=[(20\times 0.9051)+(21\times 0.0027)+(23\times 0.0922)]$

$\text{Average atomic mass of neon}=20.2793u$

Hence, the atomic weight of the neon is 20.2793 units.