Silicon, which makes up about 25 % of the Earth’s crust by mass, is widely used in the modern electronics industry. It has three naturally occurring isotopes, Si-28, Si-29, and Si-30. Calculate the atomic mass of silicon.
Isotope Isotopic Mass % Abundanc
Si-28 27.976927 92.23
Si-29 28.976495 4.67
Si-30 29.973770 3.10

28.0855089586

Explanation:

Isotopes are different kinds of the same atom differing in the number of neutrons but having the same number of protons or atomic number.

To calculate the atomic mass of silicon, we need to take into account the different isotopes. Since we have the complete abundances of each in percentages and their masses, we can multiply the abundance of each in percent by the masses and all the results together.

Si = [92.23/100 * 27.976927] + [4.67/100 * 28.976495] + [3.1/100 * 29.973770] = 25.8031197721 + 1.3532023165 + 0.92918687 = 28.0855089586