EES 0836 Lecture Notes - Lecture 4: Atomic Number, Beta Decay, Nuclear Fission
3 Apr 2016
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Lecture - 4: nuclear fission, what"s it all about, what"s in a nucleus, the nucleus of an atom is made up of protons and neutrons. Each is about 2000 times the mass of the electron, and thus constitutes the vast majority of the mass of a neutral atom (equal number of protons and electrons) Proton has positive charge; mass = 1. 007276 a. m. u. Neutron has no charge; mass = 1. 008665 a. m. u. Proton by itself (hydrogen nucleus) will last forever. Neutron by itself will decay with a half-life of 10. 4 min. Size of nucleus is about 0. 00001 times size of atom: atom is then mostly empty space, puzzle: carbon-based a. m. u, the atomic mass unit (a. m. u. ) is based on 12c. Defined to be 12. 0000000000 a. m. u: adding up the constituent masses: All together: 12. 09894: but this isn"t 12. 000000. At close scales, another force takes over: the strong nuclear force: the strong force operates between quarks: the building blocks of both protons and neutrons.
