Enter the percentage abundance and mass of up to 5 different isotopes into the average atom mass calculator. The calculator will display the average atomic mass of the isotopes.
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Average Atomic Mass Formula
The following formula is used to calculate the average atomic mass of a substance.
AM = f1M1 + f2M2 +… + fnMn
- Where AM is the average atomic mass
- fn is the fractional percent of the isotope
- M is the mass of the isotope
Average Atomic Mass Definition
An average atomic mass is defined as the average mass of all isotopes within a given substance.
How to calculate average atomic mass?
How to calculate average atomic mass?
- First, determine the fractional percent of each isotope in the substance
For example, chlorine has two major isotopes. 1 with 75.77 percent of atoms and 1 with 24.23 percent of atoms. These two percentages would be the fractional percents of those isotopes.
- Next, determine the masses of each isotope
Using the same example above, this would be 35 and 37 amu respectively.
- Finally, calculate the average atomic mass
Calculate the average atomic mass using the information from steps 1 and 2 and the formula above.
FAQ
The average atomic mass is the average mass of all of the isotopes that make up a substance.
The fractional percent is the total percentage of a particular isotope in a substance.
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