What is the volume(cubic meter) and density(kg/cubic meter) of electron,proton,neutron?

Question

i want to know the volume and density of electron,proton,neutron(subatomic particle) in S.I SYSTEM OR M.K.S SYSTEM.

Answer 1

The electron, proton, and neutron do not really have a size or volume.  If you have enough pressure, you can pack any number of them in a small space.  And if you have no pressure, they can be as large as you want, or can imagine.

But, there is something called the "classical size".

Electron size: 1.13E-43 cubic meters, density = 8.06E+12 kg/cubic meter.

Proton size: 1.65E-15, density = 8.89E+16

Neutron size: 1.65E-15, density = 8.90E+16

Answer 2

You can assume the particles are spheres so the density is just:

rho = mass / (4/3 pi r^3)

You can look up all the masses on wikipedia.

You can look up the characteristic sizes of the proton and neutron.

The electron is (as best we can tell) a point particle, but if you don't want to just say it has infinite density, you could use the upper limit on its size to establish a lower limit on its density.

Lemme look up a number you could use:

PDG doesn't have anything which kind of surprises me a little that nobody has quantified exactly how sure we are that the electron is a point particle and not a composite of some kind.  So you do just have to say its infinite.

The classical electron radius isn't really its size--that's just a parameter that describes how big it would have to be for its electrostatic self-energy to equal its mass.  It's many orders of magnitude bigger than the size of where it carries its mass/energy.  The nucleons are composite particles and do have a size that can be probed by experiment.  Under low pressure, they do not just expand.  The strong force keeps them bound to a certain size (which is much larger than their classical size).

And your "sizes" for the nucleon are on the order of the radii--way way low for volumes.

---I'm a little bothered by saying the electron is infinitely dense since that per se violates special relativity.  The best solution to the problem I can think of is to use the compton wavelength as a sort of characteristic size, but that depends on the momentum, so it really COULD be as big or small as you want to imagine.