In physics, the neutron is a subatomic particle with no net electric charge and a mass of 940 MeV (very slightly more than a proton). The nucleus of most atoms (all except the most common isotope of Hydrogen, which consists of a single proton only) consists of protons and neutrons. Outside the nucleus, neutrons are unstable and have a half-life of about 15 minutes, decaying by emitting an electron and antineutrino to become a proton. The same decay method (beta decay) occurs in some nuclei. Particles inside the nucleus are typically resonances between neutrons and protons, which transform into one another by the emission and absorption of pions. A neutron is classified as a baryon, and consists of two down quarks and one up quark.
The characteristic of neutrons which most differentiates them from other common subatomic particles is the fact that they are uncharged. This property of neutrons delayed their discovery, makes them very penetrating, makes it impossible to observe them directly, and makes them very important as agents in nuclear change.....blah blah blah.....now my head is spinning!
