1. BIG topics... Light (electromagnetic radiation)  particle/wave dual nature of light  c, λ, ט, E & h Quantum theory (wave mechanical model)  Bohr model of Hydrogen atom  absorption/emission  quantum numbers & 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

6. GIVEN: h  x 10 -34 J s c = 3.00 x 10 8 m/s = ? = 1.0 x 10 -3 nm = ???? m WORK: = c = 3.00  10 8 m/s 1.0 x 10 -12 m = 3.0 x 10 20 s -1 Find the energy of a photon with a wavelength of 1.00 x 10 -3 nm. E = hvc = λv  = (6.626 x 10 -34 J s)(3.0 x 10 20 s -1 ) E = 1.99 x 10 -13 J E = hc λ

7. 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

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

9. 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…

10. Excitation of Hydrogen Atoms

11. Return to Ground State

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

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

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

15. Preview....Orbital Shapes