- Photoelectric Effect: the wavelength of the photon is related to the frequency of the radiation
- When a photon is absorbed or emitted by an atom or molecule, energy is increased or decreased by an amount equal to the energy of the photon Planck’s Constant
- Planck’s Constant: defines the quantum nature of energy and relates the energy of a photon to its frequency
○ Energy can only be gained/lost in whole-number multiples of hv (h is planck’s constant)
○ Quantum: small “packets” of energy
PES Graphs
- Used to measure ionization energies (binding energies)
○ Valence shell has the least binding energy
○ Highest binding energy = closest to the nucleus
- Each peak represents electrons in a sublvl & the height of the peak corresponds to the number of electrons in each sublevel
○ Always label peaks with sublevels; all electrons in the same sublvl have same binding energy
- When asked to draw peak, take into account nuclear charge (how many protons)
○ Remember: Nuclear charge increases down a group & across a period → if nuclear charge is stronger then the peak will be more left