Now practice calculating average atomic mass.

The first problem will give you step by step hints. What is the average atomic mass of nitrogen? Click on the blanks to check your answers.

Change the percent abundance of nitrogen 14 to a decimal. Interactive button. Assistance may be required. __________ 0.9963

Change the percent abundance of nitrogen 15 to a decimal. Interactive button. Assistance may be required. __________ 0.0037

Plug exact weights and percentages abundance into the following equation:

(exact weight of isotope 1 x percent abundance of isotope 1) + (exact weight of isotope 2 x percent abundance of isotope 2)
= average atomic mass

Interactive button. Assistance may be required. (__________ 14.003074 x Interactive button. Assistance may be required. __________) 0.9963 + Interactive button. Assistance may be required. ( __________ 15.000108 x Interactive button. Assistance may be required. __________) 0.0037
Interactive button. Assistance may be required. __________ 13.95126 + Interactive button. Assistance may be required. __________ 0.05550 =
Interactive button. Assistance may be required. __________ 14.007 amu

Now calculate the following on your own.

Chlorine

Magnesium