Mass Number and Isotopes

Question 1

What is the definition of relative atomic mass?

Answer 1

Relative atomic mass (Aᵣ) is the weighted average mass of the atoms of an element, compared to 1/12th the mass of a carbon-12 atom.

Question 2

What is the definition of relative molecular mass?

Answer 2

Relative molecular mass (Mᵣ) is the sum of the relative atomic masses (Aᵣ) of all the atoms in a molecule, compared to 1/12th the mass of a carbon-12 atom.

Question 3

What is the definition of an isotope?

Answer 3

Isotopes are atoms of the same element with the same number of protons but different numbers of neutrons.