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Module 4 - Chapter 13 - Quantum Physics II - Coggle Diagram
Module 4 - Chapter 13 - Quantum Physics II
Conservation of energy
Energy of each individual photon is conserved
Photon energy frees a single electron from the surface of the metal in a one to one interaction
Any remainder is transferred into kinetic energy
Work function - minimum energy to free electron from a certain metal
Energy of a single photon = work function + kinetic energy of electron
Maximum kinetic energy
Some electrons are closer to the positive metal ions than others
Relative positions affect how much energy is required to free an electron, most electrons need more than the work function
An electron that requires the minimum energy to be freed has the maximum kinetic energy
If a photon strikes a metal at the threshold frequency, it only has enough to free a surface electron, so no energy is transferred to kinetic
Graph of KE max agaisnt frequency
KE max = hf - work function
Gradient is planck costant
y intercept = -(work function)
Different materials
All metals have the same gradient
Every metal has a different work function and thus different threshold frequency
x intercept is the threshold frequency
Particle duality
Diffracting particles
Wave-particle duality describes how matter has both wave and particles properties
Photon model suggests photos can be particles, by EM radaiton can diffract, which is wave behaviour
Electron diffraction
Electrons are normally described as particles, but they are also able to diffract
Electrons spread out like waves when they pass through a small gap between the carbon atoms in polycrystalline graphite
de Broglie equation
Wavelength was inversely proportional to its momentum
Accelerated particles
If kinetic energy of a particle decreases by 2x, its wavelength increases by √2
Bonded electrons
As particles become larger, their wave properties become harder to observe
Mass of individual protons is much greater than electrons
Momentum of protons is much greater than electrons, so their wavelength is much smaller
