Subatomic Particles

particle	mass (kg)	radius (fm)
electron	9.109 × 10−31	0.01
proton	1.673 × 10−27	1.1
neutron	1.675 × 10−27	1.1

The radii of protons and neutrons can only be given approximately,
since they have fuzzy surfaces. For comparison, a
typical atom is about one nanometer (1 million femtometer) in radius.