There are three isotopes of silicon. they have mass numbers of 28, 29 and 30. the average atomic mass of silicon is 28.086amu. what does this say about the relative abundances of the three isotopes?

The abundance of Si-28 isotope is the highest as compared to the other isotopes.

Explanation:

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

Formula used to calculate average atomic mass follows:

We are given:

Three isotopes of Silicon, which are Si-28, Si-29 and Si-30.

Average atomic mass of silicon = 28.086 amu

As, the average atomic mass of silicon is closer to the mass of Si-28 isotope. This means that the relative abundance of this isotope is the highest as compared to the other two isotopes.

Percentage abundance of Si-28 isotope = 92.2%

Percentage abundance of Si-29 isotope = 4.7 %

Percentage abundance of Si-30 isotope = 3.1%

Hence, the abundance of Si-28 isotope is the highest as compared to the other isotopes.