• 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