Neutron size and scale context

The neutron is the electrically neutral baryon that, together with the proton, builds atomic nuclei. A free neutron decays by beta-minus decay into a proton, an electron, and an electron antineutrino in about 15 minutes, while neutron-rich matter can persist inside neutron stars. Read its scale context, comparisons, and journey links on the canonical object page.

ProtonBaryon·1.68 fm

NeutronBaryon·~1.72 fm

Plutonium-244 NucleusAtomic nucleus·15 fm

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Particles

Proton

The proton is the positively charged particle that gives every atomic nucleus its identity. Less than 1% of a proton’s mass comes from the masses of its quarks; almost all of the rest comes from the energy of quarks and gluons bound by the strong force.

Scale fact1.68 fmdiameter

Object class: Baryon

Particles

Neutron

Scale fact~1.72 fmdiameter

Object class: Baryon

Particles

Plutonium-244 Nucleus

The plutonium-244 nucleus is the heavy atomic nucleus of a long-lived plutonium isotope, built from 94 protons and 150 neutrons. It was forged in rare neutron-rich explosions before the Solar System formed, and its 81.3-million-year half-life made it an important extinct radionuclide in early Solar System history.

Scale fact15 fmdiameter

Object class: Atomic nucleus
Composition: 94 protons, 150 neutrons