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SQA Higher Chemistry Relative atomic mass

Relative atomic mass

This page covers the following topics:

1. Relative atomic mass

Relative atomic mass is a weighted average mass of all the isotopes of an element. Weighted means that it takes into account the natural abundance of each isotope.

To find the relative atomic mass from given atomic masses of isotopes and their abundances, multiply corresponding atomic masses and their abundances in decimals and add the multiplication products together. If you use abundances as percentages, divide your final result by 100%.

Relative atomic mass

1

Magnesium has three stable isotopes, ²⁴Mg (79%), ²⁡Mg (10%) and ²⁢Mg (11%). What is the relative atomic mass of magnesium?

Magnesium has three stable isotopes, ²⁴Mg (79%), ²⁡Mg (10%) and ²⁢Mg (11%). What is the relative atomic mass of magnesium?

2

Chlorine has two stable isotopes, ³⁡Cl (75%) and ³⁷Cl (25%). What is the relative atomic mass of chlorine?

Chlorine has two stable isotopes, ³⁡Cl (75%) and ³⁷Cl (25%). What is the relative atomic mass of chlorine?

3

Copper has two main isotopes, ⁢³Cu and ⁢⁡Cu with their abundances respectively being 70% and 30%. What is the relative atomic mass of copper? The data provided has been adjusted for the question.

Copper has two main isotopes, ⁢³Cu and ⁢⁡Cu with their abundances respectively being 70% and 30%. What is the relative atomic mass of copper? The data provided has been adjusted for the question.

4

What is the relative atomic mass of tungsten? Give your answer to 2 decimal places.

What is the relative atomic mass of tungsten? Give your answer to 2 decimal places.

5

What is the relative atomic mass of platinum correct to 3 decimal places? The data in the table has been adapted for the question.

What is the relative atomic mass of platinum correct to 3 decimal places? The data in the table has been adapted for the question.

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