Particles

Particles

1. Atoms are made up of protons, neutrons and electrons

   • atomic number= number of protons
   • Nucleon number= number of neutrons + protons
   • Isotopes have same number of protons but different number of neutrons
   • In an uncharged atom, number of protons = electrons
     • Becomes an ion if it gains/loses electrons
   • specific charge = charge/mass

2. Strong nuclear force holds nuclei (protons + neutrons) together in a stable isotope

   • Attractive range from 0.5fm to 3-4fm, below 0.5 becomes repulsive
   • Alpha emission happens in a 'big' nucleus
     • compromises 2 protons and 2 neutrons
   • Beta-minus decay happens in a neutron rich nucleus
     • electron and an antiparticle (antineutrino) are emitted from nucleus
     • neutron in the nucleus changes into a proton