Announcements

1
Announcements

• To join clicker to class today
• Turn on the Clicker (the red LED comes on).
• Push Join button followed by 20 followed by
  the Send button (switches to flashing green LED
  if successful).

• Pick up paper copy of periodic table if you do
  not have text here or a table you can write on.

Review

• History of atomic models
• e- embedded in positive sphere (1900)
• Rutherford Experiment (1910) lead to idea of
  dense positively charged nucleus with e-
  somewhere outside

2
Review

• e- dont fall into nucleus because trapped in
  quantized energy levels.
• Evidence quantization of light energy (photons,
  photoelectric effect) plus emission and
  absorption line spectra.
• Can calculate energy of emission or absorption
  from ?E Ef-Ei
• Simple equation for energies of light from H
  atoms.
• Rydberg equation 1/??? R(1/nf2 - 1/ni2),
• where R a constant, ? observed wavelength, nf
  integer (quantum number) representing the
  final energy level, ni integer(quantum number)
  representing the initial energy level.
  n1,2,3....
• Do not need to know since just a special example
  of ?E Ef-Ei

3
Review

• First simple model Bohr model En -Rhc/n2,
• Rhc 2.179 x 10-18 J/atom
• note E lt 0
• highest E-level is n 8??with E 0
• Problem orbiting e- should fall into nucleus.

4
Quantum Rules

• Pauli Exclusion Principle No two e- in the same
  atom may have all four quantum numbers the same.
• n (principle) 1, 2, 3 ...8 (specifies shell)
• l (angular momentum QN) 0, 1, ...n -1 (0s,1p,
  2d, 3f)
• ml(magnetic QN) 0, 1, ... l.
• ms1/2