1. A Better Understanding of the Atom Required a Better Understanding of Light White light passed thru a prism produced a rainbow Light generated by an atomic gas produced a line spectrum (when the light passed thru a prism) Why? Understanding this lead to a better understanding of the atom

2. Looking at Light Scientists knew light was waves (transverse waves) Light is Electromagnetic Radiation

3. The Electromagnetic Spectrum Speed of light Speed = c = f c = 3.0 x 10 8 m/s Light is much more than just visible light!!

4. Looking at Light Scientists Could Explain the Prism Effect because light was a wave But LINE SPECTRA????

5. “Unexplained” Phenomena of Light (in early 1900s) Blackbody Radiation Photoelectric Effect –understanding these required some revolutionary ideas –Quantization of energy

6. Photoelectric Effect Einstein’s Explanation: photons of light E photon = hf Wave-Particle Duality of Light h = 6.626 x 10 -34 J s (Planck’s constant)

7. Light and Energy The energy of light is actually determined by the wavelength or frequency. A given wavelength or frequency corresponds to a particular energy. What is the energy of a photon of light that has a frequency of 99.9 MHz?

8. Bohr’s Model of the Atom

9. Bohr’s Model and Line Spectra Increasing E Electron in Lowest Energy electron absorbs energy Electron releases energy Releases enough energy to change energy levels  releases as a photon This energy will appear as a single line of light (a single frequency or a single wavelength) Electron could absorb enough energy to reach this energy level Then, it could lose enough energy at once to return to original energy level If the electron absorbs enough energy to reach this energy level It could lose enough energy (as two separate photons) to drop from on level to the next and then to the next This energy and photon is lost separately

10. Current Model of the Atom electrons do NOT orbit nucleus in circular pattern! current model based on quantum theory electrons exist in probability clouds called orbitals

11. s-orbitals 1s 2s All s subshells contain a single orbital called an s orbital. Every s orbital is spherical; the difference between a 1s, 2s, 3s, etc. is the size.

12. p-orbitals All p subshells contain three orbitals called p orbitals, one on each of the three axes. Every p orbital is dumbbell shaped; the difference between 2p, 3p, 4p, etc. is the size.

13. d-orbitals All d subshells contain five orbitals called d orbitals. The difference between 3d, 4d, etc. is the size.

14. Increasing Energies of Subshells 5d 4f 6s 5p 4d 5s 4p 3d 4s 3p 3s 2p 2s 1s

15. Give the electron configuration, and determine the number of valence electrons for... F1s 2 2s 2 2p 5 valence electrons P1s 2 2s 2 2p 6 3s 2 3p 3 valence electrons

16. Group 1 (IA) Group 2 (IIA) Group 13 (IIIA) Group 14 (IVA) Group 15 (VA) Group 16 (VIA) Group 17 (VIIA) Group 18 (VIIIA) Li 2s 1 Be 2s 2 B 2s 2 2p 1 C 2s 2 2p 2 N 2s 2 2p 3 O 2s 2 2p 4 F 2s 2 2p 5 Ne 2s 2 2p 6 Na 3s 1 Mg 3s 2 Al 3s 2 3p 1 Si 3s 2 3p 2 P 3s 2 3p 3 S 3s 2 3p 4 Cl 3s 2 3p 5 Ar 3s 2 3p 6 K 4s 1 Ca 4s 2 Ga 4s 2 4p 1 Ge 4s 2 4p 2 As 4s 2 4p 3 Se 4s 2 4p 4 Br 4s 2 4p 5 Kr 4s 2 4p 6 Rb 5s 1 Sr 5s 2 In 5s 2 5p 1 Sn 5s 2 5p 2 Sb 5s 2 5p 3 Te 5s 2 5p 4 I 5s 2 5p 5 Xe 5s 2 5p 6 Cs 6s 1 Ba 6s 2 Tl 6s 2 6p 1 Pb 6s 2 6p 2 Bi 6s 2 6p 3 Po 6s 2 6p 4 At 6s 2 6p 5 Rn 6s 2 6p 6 Valence Configurations of Main Group Elements

17. Orbitals and the Periodic Table s- block p-block d-block f-block