Why is a neutron slightly bigger than a proton?

Answer 1

It has a greater mass.

"Mass of proton : 1,6726 x 10^(-27) kg
Mass of neutron: 1,6749 x 10^(-27) kg
Mass of electron: 0,00091x10^(-27) kg"

"Still, the basic structure of a neutron is three quarks: 1 up, 2 down. Likewise, a proton is three quarks: 2 up, 1 down. An up quark and a down quark are not the same thing. Charge and mass are different. Quarks can be put together as protons, neutrons, and a wide variety of other particles. How they are assembled has a large effect on mass. Due to both quark mass and assembly details, a neutron ends up with more mass than a proton.
"

"http://www.newton.dep.anl.gov/askasci/gen01/gen01078.htm

Answer 2

A neutron will break down into it's natural parts in about 13 ms. They are : a proton and a electron.
In the nucleus of heavy elements protons and neutrons are held very close together by the Strong nuclear force when a Neutron breaks down, its electron is immediately captured by an adjacent proton, making it a neutron. So they just changed places! in real heavy elements, sometimes an electron is not captured, because there are just too many packed too close together. So, the electron escapes the element and is known as a Beta particle. This makes the element unbalanced and after loosing more electrons, it will cast off a large chunk of its core(2 protons and 2 neutrons). This is called a alpha particle and is the inside of a helium atom. The Whole action is called Radioactive! Just think of the nucleus as constantly changing or boiling.

Answer 3

Maybe because a neutron is electrically neutral - its like a proton plus an electron (positive plus negative).
Just an idea.

Answer 4

I believe that a neutron contains the equivalent of both a proton and an electron inside of it.

Answer 5

No one knows. It is simply one of the facts of particle physics that one learns to deal with. Actually, "bigger" isn't strictly accurate -- the better term is "heavier".

Answer 6

It's a mystery of science.

Honestly, no one knows why.