“A” students work (without solutions manual) ~ 10 problems/night .

1. “A” students work (without solutions manual) ~ 10 problems/night. Dr. Alanah Fitch Flanner Hall 402 508-3119 afitch@luc.edu Office Hours Th&F 2-3:30 pm Module #18B: Color

2. Biological Nutrients Sc Ti V Cr 130 Mn 135 Fe 126 Co 125 Ni 124 Cu 128 Zn 138 Nearly All involved in color Industrially Important

3. Two competing Trends Why do electrons get pulled in? More Nuclear Charge holding electrons in closer More Electrons Pattern for number of oxidation states Related to shape of orbitals! Inability to shield added positive charge in the nucleus

4. z + x + + y z x + + y Transition Metals: 5 orbitals (10 electrons) 1. d block guys (and gals) 2. d orbitals are ~ clover leaf in shape 3. How well does the orbital “shield” or “cover” the positive charge of the nucleus? z z x2-y2 xy x x y y z z yz x xz y

5. Cl- Cl- Cl- + Cl- Cl- Cl- z xy x Enter on x,y,z axis y Cl begins Approach to minimize charge repulsion How will the incoming Cl- interact individually with the 5 d orbitals?

6. z Cl- xy x + z y z x Cl- + Cl- y x + y Cl- yz z z x + x + Cl- y xz y Incoming Cl- see little e Incoming Cl- bumps into d orbital e

7. Initially all orbitals same energy • Incoming anion interacts with d orbitals • Energy levels change due to the interaction • 3 orbitals move down in energy • 2 move up z z z xy x + + x + Cl- y z y y x + y z Cl- Cl- Cl-

8. Suppose it is :NH3 instead of Cl- What do you think will happen? Cl- .. N z z x x + + y y z z z2 D orbital energy in absence of ligands Greater Orbital Splitting with Nitrogen charge dense lone pair (localized) CN->NO2->en>NH3>NCS->H2O>F->OH->Cl->SCN->S2->Br->I- Strong field Weak field Explain what you observe for F,Cl, Br,I

9. Crazy Painters Bernardino Ramazzini 1633-1714 De Morbis artificum diatriba Vernatti: Report to Royal Society White lead manufacture illnesses 1678 Goya’s Saturn

10. The Artist’s Palette (<1850) 5 Primary colors: blue various copper coordination complex

11. xy xz yz Copper Coordination Complexes: Blue Cu2+: s0d9  D orbitals with no ligands near by decreasing Electron energy (stable orbitals)

12. How our eyes sense light 1.Pure pink light is emitted between 400-430 2.Eyes will see this as pink 3.The brain also perceives pink when the eyes see light in which the wavelengths at 500 and above 650 are removed. 4. The brain is adding up total voltage signals from three different receptors (blue, green, and red) 5. Total voltage is similar to that for pure pink

14. The Artist’s Palette (<1850) 5 Primary colors: blue various copper coordination complexes red Minium Pb2+2Pb4+O3

15. 2e

17. The Artist’s Palette (<1850) 5 Primary colors: blue various copper coordination complexes red Minium Pb2+2Pb4+O3 yellow Litharge PbO Yellow Chrome PbCrO4 Lead Antimonate, Lead Tin I, Lead Tin II

18. Charge Transfer Based Colors Metal to Ligand Charge Transfer Intervalence Charge Transfer Each one of these has an oxidation/reduction Energy low enough to be excited by visible radiation

20. Electron transfer drives color

21. :O :O Cr :O O: Chromium: 1. Identified when found as the mineral crocoite in late 1700s (PbCrO4) 2. Main oxidation states: s2d4 = 0 s0d0 = +6 s2d1 = +3 [Cr6+O4]2- Note electrons on Oxygen pointing in toward cationic Cr6+

22. :O :O Cr :O O: 1. Can Oxygen anion give electrons to chromium?, 2. What would be the energy/electron? 3. What wavelength would that translate to?

23. :O :O Cr :O O: F=9.6485x104

24. why does a fire look red-hot? Wavelength Absorbed: Observed Color Violet 400- 460 nm greenish-yellow Indigo Blue 450-490 red Green 490-570 violet Yellow 570-590 dark blue Orange 590-610 blue Red 610-700 green absorb high energy, short wavelength (<400 nm) observe red What color does CrO42- give us?

25. Mix for orange Mix for green The Artist’s Palette (<1850) 5 Primary colors: blue various copper coordination complexes red Minium Pb2+2Pb4+O3 yellow Litharge PbO Yellow Chrome PbCrO4 Lead Antimonate, Lead Tin I, Lead Tin II Black Kohl, PbS

27. Mix for orange Mix for green The Artist’s Palette (<1850) 5 Primary colors: blue various copper coordination complexes red Minium Pb2+2Pb4+O3 yellow Litharge PbO Yellow Chrome PbCrO4 Lead Antimonate, Lead Tin I, Lead Tin II Black Kohl, PbS White cerruse PbCO3

28. xy xz yz xy xz yz Cu2+: s0d9 Pb2+: s2d10p0  Which one has electrons that can be promoted and has space in the higher orbital to accept an electron?

29. Lead crocoite Lead wulfenite Lead carbonate

32. Where did all the lead go? Decade Estimate lbs white lead/housing unit 1914-23 110 1920-29 87 1930-39 42 1940-49 22 1950-59 7 1960-69 3 1970-1979 1 TiO2 makes inroads particularly in Europe White lead restricted Chicago Soils

33. xy xz yz xy xz yz xy xz yz Replacement pigment: TiO2 Ti2+: s2d0 Cu2+: s0d9 Pb2+: s2d10p0  Which one has electrons that can be promoted and has space in the higher orbital to accept an electron?

34. “A” students work (without solutions manual) ~ 10 problems/night. Dr. Alanah Fitch Flanner Hall 402 508-3119 afitch@luc.edu Office Hours Th&F 2-3:30 pm Module #18: Color chemistry