1. BIG topics... Light (electromagnetic radiation)  particle/wave dual nature of light  c, λ, ט & E Quantum theory (wave mechanical model)  Bohr model of Hydrogen atom  absorption/emission  orbital shapes Electron configurations  orbital, e - configuration  noble gas notation  Aufbau, Pauli & Hund

2. Waves Wavelength ( ) - length of one complete wave. Common units: m or nm Frequency ( ) - # of waves that pass a point during a certain time period Common Units: hertz (Hz) = 1/s = s -1 Amplitude (A) - distance from the origin to the trough or crest Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

3. Wavelength and Frequency E = h c =  c = speed of light (3.0 x 10 8 m/s)‏ = frequency (s -1 )‏  = wavelength (m)‏ E = energy (Joules or J)‏ h  = Planck’s constant (6.626 x10 -34 J s)‏ = frequency (s -1 )‏ “nu” “lamda” Highest energy Moderate energy Lowest energy

4. Visible part of EM SPectrum PRISM Slit Ray of White Light Waves 1 / 33,000 ” long Waves 1 / 70,000 ” long R ed O range Y ellow G reen B lue I ndigo V iolet 400 nm – 700 nm

5. Electromagnetic Spectrum

7. Excitation of Hydrogen Atoms

8. Return to Ground State

9. An Excited Lithium Atom Photon of red light emitted Li atom in lower energy state Excited Li atom Energy

10. Quantum Theory Max Planck (1900)‏ Max Planck (1900)‏ Observed - emission of light from hot objects Observed - emission of light from hot objects Concluded - energy is emitted in small, specific amounts (quanta)‏ Concluded - energy is emitted in small, specific amounts (quanta)‏ Quantum - minimum amount of energy gained or lost by an atom Quantum - minimum amount of energy gained or lost by an atom Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

11. Continuous vs. Quantized Energy Energy A B continuous quantized A continuous B quantized

12. Bohr Model of Hydrogen Nucleus Possible electron orbits e Great theory, BUT it turned out to be totally wrong!! Next week we’ll see a better theory Further away from nucleus means higher energy level…

13. Emission Spectrum of Hydrogen 1 nm = 1 x 10 -9 m = “a billionth of a meter” 410 nm434 nm486 nm656 nm

14. Continuous and Line Spectra light Na H Ca Hg 400 450 500 550 600 650 700 750 nm Visible spectrum  (nm)

15. Preview....Orbital Shapes