How to Calculate the AMU

The atomic mass unit (amu) is a relative unit of mass used in the metric system to describe atomic weight. It is equivalent to one-twelfth of the mass of an atom of carbon-12 (See References 1). The atomic mass unit for an element can be found on the periodic table, or it can be calculated.

Instructions

1. Determine the atomic weight of an atom of a particular element by looking at the periodic table. The number located directly under the element symbol expresses the atomic weight of an element in atomic mass units.

2. Write down the number of grams of the substance.

3. Divide the number of grams of the substance by 0.60221415 x 10(-24).

4. Record the result of your calculation. This is the atomic weight of your substance in amus.

References

• "General Chemistry, Seventh Edition;" Kenneth Whitten, Ph.D., Raymond Davis, Ph.D., M. Peck, Ph.D., & George Stanley, Ph.D.; 2004