The Electron

Subatomic particles
1. Protons
  1. Mass = 1 u
  2. Charge = +1
2. Neutrons
  1. Mass = 1 u
  2. Charge = 0
3. Electrons
  1. Charge = -1
  2. Mass = 1/1840 u
4. Unified atomic mass unit
  1. Unit of mass used to express atomic and molecular masses
  2. Symbol = u
  3. 1.66 x 10*-27 kg
Energy of an electron
1. E = qV
  1. E = energy
  2. q = charge
  3. V = voltage
2. Measured in electronvolts
  1. 1 eV = 1.6 x 10*-19
3. Energy conversion of a charged particle in an electric field
  1. Potential to kinetic or vice versa
  2. qV = 1/2 mv*2
Thermionic Emission
1. The emission of electrons from the surface of a hot metal
2. Work function
  1. Minimum energy needed to remove the loosest electrons from the surface of a metal
3. Occurs over 800 degrees C
Cathode Ray Tube
1. Components
  1. A vacuum inside a glass tube
  2. A hot filament
  3. An anode & a cathode
  4. A fluorescent screen
2. Thermionic emission occurs at the cathode
3. Properties of cathode rays
  1. Travel in straight lines
  2. Cause zinc sulphide to give out light when they strike it
  3. They have kinetic energy
  4. Deflected in electric or magnetic fields
  5. Produce X-Rays
X-rays
1. Electromagnetic radiation of very high frequency
2. Properties
  1. Electromagnetic waves
  2. Penetration
  3. Ionisation
Photoelectric effect
1. Emision of electrons from the surface of a metal due to electromagnetic radiation of a suitable frequency hitting the metal
2. Photon
  1. Bundle of light energy
  2. E = hf
    1. E = energy
    2. h = Planck's constant
    3. f = frequency

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