Most of the mass of the atom is provided by what?

1 Answer
Jan 11, 2017

The nucleus of the atom accounts for about #99.95%# of the mass of the atom, with electrons contributing a very small portion.


We know that the proton and neutron have very similar masses (though not identical!) and that each outweighs the electron by nearly a 2000:1 ratio.

So, the nucleus is the location of virtual all the mass of the atom.

This is why, for example, if we need to look up the molar mass of a sodium ion, #Na^+#, we are safe in using the atomic molar mass of sodium, with no "correction" necessary for the missing electron.