Question

Why are electrons smaller than protons and neutrons?

Answer 1

If by smaller you mean less massive there is a few reasons. An electron is an elementary particle whereas a neutron and a proton are formed through the bonding of quarks which are themselves elementary particles. However, the weight of the quarks make up roughly only one percent of a proton and neutron's mass. The rest is relativistic mass from the kinetic energy of the quarks and the binding energy of gluons. Making protons and neutrons much more massive than electrons.

Answer 2

One answer would be to say, well, that is just the way nature is !

Is the concept of size meaningful for an electron ? It's a very interesting question that has caused a few problems for physicists over the years.
I think of an electron as a 'point particle' in the sense that it doesn't have any internal structure, at least as far as I am aware.
We know that protons and neutrons are composite particles and the way in which the quarks hold together determines their size (proton diameter is roughly 10e-15 metres)

Answer 3

Another thought - if the electron has no internal structure, what on earth is electron spin ?
I meant 'no structure' in the sense of parts that you can pull around independently of one another.

Answer 4

http://openstudy.com/study#/updates/540ddec2e4b0d8ead1beb7c5

Answer 5

Sure, well I suppose most of that doesn't bother me, it's just that it seems to me unsymmetrical.