Question

State whether the given statement is true or false:

Atomic mass of an element is same as the mass of a single atom of that element.

• A. True
• B. False

Answer 1

The correct option is B False

Atomic mass of an element cannot be same as the mass of a single atom of that element because many naturally occurring elements exist in the form of two or more isotopes.

Isotopes are the atoms of the same elements having the same atomic number containing the same number of protons but different number of neutrons. So, their atomic masses vary. Average of atomic masses of different isotopes of the same element are taken and then the atomic mass of the element is decided.

For example, atomic mass of element carbon is 12 u. But we cannot say that mass of a single atom of carbon is 12 u, because there are different isotopes of carbon, like carbon-14 (atomic mass = 14 u), carbon-12 (atomic mass = 12 u), carbon-13 (atomic mass = 13 u), etc. Atomic mass of carbon element = 12u is just the average of these different atomic masses, and that's why it's more accurately called relative atomic mass.