Inside the atom

Inside the atom

Structure
1. So small, need an electron microscope to see them
2. Alpha scattering investigation - Rutherford
  1. Showed
    1. Positive nucleus
      1. Protons
      2. Neutrons
    2. Electrons surrounding nucleus
      1. Negative charge (-1.6x10^-19 C)
      2. Held by electrostatic attraction
  2. Procedure
    1. Alpha particles at gold foil
    2. Most went through undetected
    3. Some were deflected back at large angles
    4. Small number deflected backwards
    5. Enter text here
Isotopes
1. Different numbers of neutrons
2. Nucleon number - Protons and neutrons, mass number
Specific charge
1. Charge/Mass
Strong nuclear force
1. Force holding nuclei together
2. Overcomes electrostatic force of repulsion between protons
3. Keeps protons and neutrons together (in stable nuclei)
4. Range no more than 3-4fm
  1. Diameter of small nucleus
5. Has the same effect on two protons as on two neutrons
6. Attractive force from 3-4fm down to about 0.5fm
  1. At separation smaller than this, it is repulsive and prevents protons and neutrons being pushed into eachother
Radioactive decay
1. Alpha radiation
  1. Helium nucleus released (2 p 2 n)
2. Beta radiation
  1. Fast moving electrons
    1. Charge equal and opposite to the proton
  2. Neutron becomes a proton
  3. Antineutrino emitted
3. Gamma radiation
  1. EM radiation
  2. Can pass through thick metal plates
  3. No mass or charge
  4. Emitted from a nucleus with too much energy, after alpha or beta emission
Elusive particle
1. Energy spectrum of beta particles measured
  1. Energy appeared not to be conserved
    1. Actually carried away by particles
2. Particles were called neutrinos or anti neutrinos
3. Detected due to their interaction with cadmium nuclei in a large tank of water

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	Criado por Beth Ritchie quase 11 anos atrás