PHY 102 Lecture Notes - Lecture 20: Charge Radius, Electron Rest Mass, Atomic Number
Document Summary
Mass number (a) = atomic number (z) + number of neutrons (n) Binding energy = energy that keeps nucleus together/bound. 1 mev = 106 ev mass defect = m = (mass of z protons and n neutrons) (mass of nucleus) Eb = (total energy of z protons and n neutrons) (total energy of nucleus) nuclear mass unit = 1 u = 1. 66 x 10-27 kg electron mass = me = 9. 1 x 10-31 kg. Electron mass is much lighter than the nuclear mass unit. There are more neutrons in a nuclei than there are protons. Na = avogadro"s number of atoms m = mass per nucleon. R0 = 1. 2 x 10-15 m = 1. 2 fm. He-4 has higher binding energy because it"s more. Mass is not conserved, it can be defected. Alpha particle/helium atom (mass 4, charge 2) With an electron (mass 0, charge -1) or positron (mass 0, charge +1) With a photon (0 mass, 0 charge)
