# The ratio of the atoms of isotope-80 and isotope-100 are 6 to 5. What is the average atomic mass of the element?

Sep 25, 2016

The average mass is the element is 89 grams per mole.

#### Explanation:

There are 11 total parts in this ratio. So the total mass needs to be divided by 11.

6 parts are of isotope 80 so the mass of these parts is

$6 \times 80$ = 480 mass units.

5 parts are of isotope 100 so the mass of these parts is

$5 \times 100$ = 500 mass units.

The total mass units are the sum of the 11 parts.

480 + 500 = 980 mass units.

To find the average divide the total by 11

$\frac{980}{11}$ = 89