# Question about the comparative masses of Protons, Neutrons, and Electrons

1. ### minimal

11
Sorry if this is a really easy question, but in biology I don't normally deal with these matters, just confused about this.
Why is it that the mass of the electron is so much smaller than that of the proton or neutron, but the charge is similar to the proton (but opposite)? I'm assuming it has something to do with its rotation about the nucleus. Anyone care to shed a bit more light (and equations) on this?
Thanks

2. ### mathman

6,387
Charge of electron is exactly -1, charge of proton is exactly +1. "Why is it that the mass of the electron is so much smaller than that of the proton or neutron" is impossible to answer. However, the nucleons (made up of quarks and gluons) are completely different things from electrons, which are "elementary".

3. ### minimal

11
Thanks for the response, but perhaps I should have rephrased. What I meant to imply with my question, is that I do not understand how a charge can be essentially equal, if masses are different? I always thought charge was related to mass. If that has nothing to do with it, then the assumption can be that it is just chance, and it would be weirder if they were the same mass.
What are the kind of criteria that influence charge, or is it only empirically determined, and as of now, the only criteria is the charge itself, and we have no way of further reducing it to some sort of principle?

4. ### minimal

11
Last edited by a moderator: Jan 23, 2008
5. ### ZapperZ

29,650
Staff Emeritus
There are no accepted connection between "mass" and "charge". For all we know, these can "fractionalize" the way we have seen occurring with charge and spin. So as of now, there's no answer to your question.

Zz.

6. ### minimal

11
Great, thanks for the reply. I'm assuming I'm in error about what I'm about to say but I'd like some clarification on it please...
So there is no official relationship between charge and mass. However, there is a relationship between charge and magnetic field. And magnetic fields contain energy, which is related to mass. Does it not follow that there is some (albeit complicated) relationship between mass and charge?

7. ### ZapperZ

29,650
Staff Emeritus
If the charge isn't moving, there's no magnetic field. So already it isn't automatic that the presence of charge implies magnetic field.

Secondly, if spin and charge can be fractionalized (see Luttinger Liquid), then charge isn't an intrinsic property of magnetic spin.

Zz.

8. ### minimal

11
Excellent, thanks.