Question

Why are all atomic masses not nearly whole numbers?

a
This is because atomic masses are the weighted average of the masses of all naturally-occurring isotopes.
b
This is because of experimental error.
c
This is due to the mass of all the electrons in the atom.
d
This is due to binding energy of the atoms.

Answer 1

The correct answer is:

**a. This is because atomic masses are the weighted average of the masses of all naturally occurring isotopes.**

Atomic masses are not whole numbers because they take into account the existence of isotopes, which are variants of elements that have the same number of protons but different numbers of neutrons. Each isotope has a different mass, and the atomic mass listed on the periodic table represents the weighted average of all isotopes based on their natural abundance. This results in atomic masses that are often non-integer values.