Posted by Jill on .
How do you calculate the atomic mass of an element when an isotopic composition is given
99.985% 1H; 0.015% 2H
Please show steps to solve!

Chemistry 
bobpursley,
The idea is the sum of the parts is equal to the whole.
100*avgatomicmass= 99.985*1 + .015*2
solve for avgatomicmass. 
Chemistry 
Jill,
Bob please help further

Chemistry 
Jill,
How???

Chemistry 
bobpursley,
divide both sides by 100.
then on the right, muliply the terms and add. 
Chemistry 
Jill,
Can you please show how in long form so I know how to do it! Thanks

Chemistry/ bob 
Jill,
Help please see last entry

Chemistry 
Jill,
Can you please show how in long form so I know how to do it! Thanks

Chemistry 
Jill,
ANYONE!!!

Chemistry 
DrBob222,
Here is what Bob Pursley wrote.
100*avgatomicmass= 99.985*1 + .015*2
Here is a rewritten form of his equation although his instructions for solving the equation are simple.
100*x = [99.9985*1 + 0.015*2]
solve for x which is the average atomic mass.