The mass of a #"_10^20Ne# atom is is 19.99244 amu. How do you calculate its mass defect?

1 Answer
anor277
Jan 12, 2017

By taking the difference between the sum of the nucleon masses and the atomic mass.

Explanation:

I will not consider electronic mass here. We know (the masses should have been provided in the question!) that the neutron mass is #1.008701*"amu"# and the proton mass is #1.007316*"amu"#.

Given #"10 protons"# and #"10 neutrons"#, there combined mass is #10xx{1.008701+1.007316}*"amu"=20.16017# #"amu"#.

And thus the mass defect is, #20.16017# #"amu"-19.99244# #"amu"#
#=0.16773*"amu"#. And this seems a rather large value? I would check this with your text, or with someone who deals with particle physics problems. You are in the chemistry section, and certainly I don't have a feel for the right order of magnitude here.

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