QUANTUM

QUANTUM

1. Photoelectric Effect

   • When light of a high enough frequency is incident on a metal surafce electrons are ejected
   • Electrons absrob energy from incident radiation so can overcome attractive forces of nuclei
   • Threshold frequency is minimum frequency required for electron to be emitted
     • Each metal has diffferent threshold frequency
   • Range of energies are produced
     • Maximum value depends on colour

2. Ionisation

   • when an electron is removed from an atom
   • Ionisation energy: The amount of energy needed to completely remove an electron from the atom from the ground state (n=1)

3. Excitation

   • Atoms absorb specific energies from colliding electrons
     • Electrons overcome electrostatic attraction between itself and nucleus
     • Incident electron makes atomic electron move to a higher shell
   • Excitation energy is always less than ionisation energy
   • When electron returns to original shell a photon of the same energy is emitted

4. Wave Particle Duality

   • Light can be described as a particle and other times as a wave
   • Waves: Reflection, Refraction, Interference, Diffraction, Polarization
   • Particle: Photoelectric effect

5. Energy Levels

   • hf = E1 - E2
     • Measured in J
       • 1eV = 1.9 x 10-19 J
     • Measured in eV
       • The kinetic energy carried by an electron after it has been accelerated through a potential difference of 1 volt