What percentage of the mass of an atom does the electron represent? The weight of the electron is 5.486*10^-4 and weight of the proton is 1.0073

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jerichorayel | College Teacher | (Level 2) Senior Educator

Posted on

Hello! :)

 

I can see that there are some lacking details in the problem.

Lets just say we have an element Chlorine.

its atomic number is 17 meaning there are 17 protons and 17 neutrons and 17 electrons.

*we can say that mass proton=mass neutron

so,

17 x 1.0073          = 17.1241

17 x 1.0073          = 17.1241

17 x 5.486x10^-4 =0.0093262

 

total amu (atomic mass unit) =    34.2575 amu

 

to get the % electron:

% electron = total amu electron/ total x 100

 = 0.0093262/34.2575  x100

 

= 0.0272% electron by mass.

 

 

hope this helps :)

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