Question

How do you find the average atomic mass?

Answer 1

When calculating the average atomic mass of an element you should be given the isotope and the percent abundance. For example (X is a made up element).

`X-45` = 44.8776 amu is 32.88% abundant.
`X-47` = 49.9443 amu is 67.12% abundant.

Note: amu stands for atomic mass unit

Given that information, you multiply the amu by the percent abundance

`.3288(44.8776) = 14.75575`
`.6712(46.9443) = 33.52261`

Then you add the two figures together to get your average atomic mass.

`14.75575+33.52261 = 48.27836`