What is the average atomic mass of an element composed of a series of isotopes, #X, Y, Z# with respective masses, #18.473*"amu", 19.962*"amu", 21.469*"amu"#, and respective abundances, #X=28.812%#, #Y=28.757%#...?

1 Answer
Feb 7, 2018

Answer:

We take the weighted average ..... and get #20.15*"amu"#

Explanation:

#"Average atomic mass"={18.473_"X"xx28.812%+19.962_"Y"xx 28.757% +21.469_"Z" xx(100-28.812-28.757)%}*"amu"#

#-=20.15*"amu"#...if I have done my 'rithmetic right...

How did I get the percentage abundance of #Z#?

And it is likely that we got the element neon. How did I know this?