Question

Helium has two naturally occurring isotopes, helium-3 and helium-4. the atomic mass of helium is 4.003 amu. which isotope is more abundant in nature? explain your answer.

Answer 1

Helium-4 is more abundant. The reason for this is because Helium-4's mass number is closer to the atomic mass of Helium than Helium-3's.

Answer 2

Answer: The abundance of He-4 isotope is the highest as compared to the other isotope.

Explanation:

Average atomic mass is defined as the sum of masses of each isotope each multiplied by their natural fractional abundance.

The equation used to calculate 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:

Two isotopes of helium, which are He-3 and He-4

Average atomic mass of helium = 4.003 amu

As, the average atomic mass of helium is closer to the mass of He-4 isotope. This means that the relative abundance of this isotope is the highest as compared to the other isotope.

Percentage abundance of He-4 isotope = 99.99%

Percentage abundance of He-3 isotope = 0.01 %

Hence, the abundance of He-4 isotope is the highest as compared to the other isotope.