Lesson: Relative Atomic Masses and Isotopic Abundance

In this lesson, we will learn how to calculate the relative atomic masses of elements based on the relative abundance of their isotopes.

Worksheet: 2 Questions

Q1:

Calculate, to 3 significant figures, the average atomic mass of the sample.

A second sample of lithium also contains a mixture of and but displays a higher abundance of . How does the average atomic mass of this sample compare with that of the first?

Q2:

Protons and neutrons have masses of approximately 1 unified atomic mass unit (u) and cannot easily be split into smaller particles. Magnesium consists of protons, neutrons, and electrons and has an atomic mass of 24.3 u. Why is the atomic mass of magnesium significantly greater than 24 u?

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