If you are not registered for ChE 361

1. If you are not registered for ChE 361 Please come see me

2. About Clicker Quizzes:1) Review previous lectures2) Review reading assignment3) Assess understanding of today’s discussion

3. The Clicker Trials • Register your i>clicker by Monday, 27 January(Registration info posted on Canvas, click on link). • You can take part in polling before registering, but scores will not be posted to Canvas until you register. • If your i>clicker is already registered for another course, there is no need to register again. • If you make a mistake registering, just re-register. i<clicker will accept the most recent registration.

4. Clicker Quizzes • You may consult with your neighbors, unless directed otherwise. • You may consult with your text, but time is limited. • Correct answer = 2 points • Incorrect answer=1 point • I drop the lowest 2 clicker grades to allow for absences/clicker problems/forgotten remotes.

5. The Clicker Games-let’s try this! • Power on your clicker i>clicker will power off after 90 minutes of inactivity. i>clicker2 will power off after 5 minutes of inactivity. • When the polling begins, Press the letter corresponding to your answer. i>clicker–green light=answer accepted; flashing red=try again. i>clicker2–a check mark ( √ ) will show up beside your answer on LCD screen. • Ask if you need help

6. Types of Bonding • Ionic • Covalent • Metallic • Van der Waals (Secondary)

7. The Periodic Table inert gases give up 1e- give up 2e- accept 2e- accept 1e- give up 3e- H He Li Be O F Ne Na Mg S Cl Ar K Ca Sc Se Br Kr Rb Sr Y Te I Xe Cs Ba Po At Rn Fr Ra Columns: Similar Valence Structure Electronegative elements: Readily acquire electrons to become - ions. Electropositive elements: Readily give up electrons to become + ions. Adapted from Fig. 2.6, Callister & Rethwisch 8e.

8. Rule #2: Stable Configurations Some electron configurations are especially stable. (Think “noble gases”)

9. f06_02_pg23 Example: Na, Cl

10. Rule #1: Electrical Neutrality Opposites attract

11. 1) Ionic Bonding Atoms take/give electrons to neighbor • Often 1 metallic & 1 non-metallic (Elements from opposite sides of table)

12. 2) Covalent bonding Atoms Share Electrons

13. f06_02_pg23 Example: H2O

14. 2) Covalent bonding Adjacent atoms share electrons to achieve stable e- configuration

15. Reality check ionic covalent Nature of the bond reported as: Percent ionic character

16. 3) Metallic Bonding • Share electrons (“sea of electrons”) • Orbitals never completely filled:Electrons jump from atom to atom

17. Section 2.7 Secondary or Van der Waals Bonding

18. Rule #3: Dipoles almost always occur

19. 4) Secondary (Van der Waals) bonding • Weak compared to primary bonds • Can significantly affect material properties

20. 4) Secondary (Van der Waals) bonding Fluctuating induced dipole moments Ion core Before: Ion core – Ion core + Ion core – + – After:

21. 4) Secondary (Van der Waals) bonding • Permanent Dipole Bonds Permanent dipole moments in the molecule. Bonds stronger than for Fluctuating • Example: H2O H H H – + – + – + O O O H H H

22. For which will VdW forces have the strongest influence on properties? Covalent bond: Where a rod meets a ball A. Graphite (Carbon) B. Diamond (Carbon)

23. Sections 3.1–3.4; 3.7 Structure of Crystalline Solids

24. Cubic xl Structures

25. Unit Cell Smallest structural unit that generates a 3-D xl (if repeated). 7 Crystal Systems—Only 7 unit cell shapes for all xl structures.

26. Crystal Systems Table 3.2

27. Crystal Systems, cont’d Table 3.2, cont’d

28. Unit cell f04_03_pg46 Cubic System a = b = c a = b = g = 90º Fig. 3.4

29. Atomic Packing Factor APF = volume of atoms in unit cell total volume of unit cell

30. Metallic xl Structures • Face-Centered Cubic (FCC) • Body-Centered Cubic (BCC) • Hexagonal Close-Packed (HCP)

31. FCC Atoms at 8 corners & 6 faces Equivalent of ? whole atoms. Atomic Packing Factor (APF)= .74 f02_03_pg42 Fig. 3.1

32. FCC Cubic structure STM of Platinum Dept. Kings.edu/chemlab, Property of IBM

33. What’s an STM image? A scanning tunneling microscope (STM) is an instrument for imaging surfaces at the atomic level.

34. Atoms…. You are under our control!

35. 1990: IBM scientist Don Eigler used an STM to move single xenon atoms on a nickel surface • The engineers moved 35 atoms to spell out "IBM" in a 10 micrometer logo.

36. FCC examples 0.3 mm Lab-grown copper (SEM) Etched Aluminum (SEM) Galena (Pb ore) Gold

37. What’s an SEM image? A scanning electron microscope (SEM) produces images by scanning a sample with a focused beam of electrons. Yields topography and composition.

38. BCC f02_03_pg42 Atoms at 8 corners & 1 in center of cube Equivalent of ? whole atoms APF = .68 Fig. 3.2

39. BCC Cubic structure STM of Aluminum (100) surface https://wiki.fysik.dtu.dk/dacapo/Examples

40. BCC examples Molybdenum Iron

41. Metallic xl Structures • Face-Centered Cubic (FCC) Cu, Al, Ag, Au, Pb, Ni, Pt • Body-Centered Cubic (BCC) Na, Fe, Cr, Mo, W • Hexagonal Close-Packed (HCP) Ti, Zn, Cd, Co, Mg

42. f07_03_pg54 • HexagonalSystem • a1 = a2 = a3 ≠ z • = 90º g = 120º Fig. 3.7

43. HCP f03_03_pg43 Atoms at 12 corners, 3 in interior, 2 centered on basal planes Equivalent of ? whole atoms (APF)= .74 Fig. 3.3

44. Hexagonal structure STM of Nickel surface structure. Dept. Kings.edu/chemlab, Property of IBM

45. Zinc hand sample Hexagonal structure

46. Hexagonal structure SEM of Fine Cadmium powder SEM of ZnOnanowires http://www.lac.tu-clausthal.de/en/arbeitsgruppen/angewandte-photonik-lac/projekte/zinc-oxide-nanowires-for-photonic-applications/ http://www.sciencephoto.com/media/8998/enlarge

47. HCP Examples Cadmium crystal bar Titanium crystals Magnesium (SEM)

48. Atomic Packing Factors BCC = 0.68 FCC = 0.74 HCP = 0.74