1 / 13

Lewis Diagrams (p. 220 – 229)

Ch. 8 – Molecular Structure. Lewis Diagrams (p. 220 – 229). A. Drawing Lewis Diagrams. Arrange atoms Singular atom is usually in the center (often Carbon) If no Carbon, least e - neg atom is in center Hydrogen is always terminal

perrin
Download Presentation

Lewis Diagrams (p. 220 – 229)

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Ch. 8 – Molecular Structure Lewis Diagrams(p. 220 – 229)

  2. A. Drawing Lewis Diagrams • Arrange atoms • Singular atom is usually in the center (often Carbon) • If no Carbon, least e- neg atom is in center • Hydrogen is always terminal • Find total # of e- available to bond (valence e- ), then divide by 2 to find available e- pairs • Place the bonding pairs between central atom and each terminal atom

  3. A. Drawing Lewis Diagrams • Determine remaining e- pairs – subtract # of bonds from #3 • Place lone pairs around terminal atoms (except H) to satisfy octet rule • Any remaining pairs are assigned to central atom • Determine whether or not central atom satisfies octet • If not, convert one or more lone pairs from terminal atoms to double or triple bonds • Certain atoms can be exceptions to octet rule – H, Be, B, S, P, Xe

  4. B. Drawing Lewis Diagrams • CF4 1 C × 4e- = 4e- 4 F × 7e- = 28e- 32e- + F F C F F 2 16 pairs of e- - 4 pairs of e- 12 pairs of e-

  5. A. Drawing Lewis Diagrams • CO2 1 C × 4e- = 4e- 2 O × 6e- = 12e- 16e- + OCO 2 8 pairs of e- -2 pairs of e- 6 pairs of e-

  6. B. Polyatomic Ions • To find total # of valence e-: • Add 1e- for each negative charge • Subtract 1e- for each positive charge • Place brackets around the ion and label the charge

  7. B. Polyatomic Ions O O Cl O O • ClO4- 1 Cl × 7e- = 7e- 4 O × 6e- = 24e- 31e- + + 1e- 32e- 16 e- pairs - 4 e- pairs 12 e- pairs 2 =

  8. B. Polyatomic Ions H H N H H • NH4+ 1 N × 5e- = 5e- 4 H × 1e- = 4e- 9e- + - 1e- 8e- 2 = 4 pairs of e- -4 pairs of e- 0 pairs of e-

  9. C. Resonance Structures • Molecules that can’t be correctly represented by a single Lewis diagram • Actual structure is an average of all the possibilities • Show all possible structures separated by double-headed arrows

  10. O O S O O O S O O O S O C. Resonance Structures • SO3

  11. F F F S F F F F B F F H O H N O Very unstable!! D. Octet Rule • Exceptions: • Hydrogen  2 valence e- • Groups 1,2,3 get 2,4,6 valence e- • Expanded octet  more than 8 valence e- (e.g. S, P, Xe)

  12. E. Drawing Lewis Diagrams • BeCl2 ClBeCl 1 Be × 2e- = 2e- 2 Cl × 7e- = 14e- 16e- + 2 8 pairs of e- -2 pairs of e- 6 pairs of e-

  13. E. Drawing Lewis Diagrams • SF6 1S× 6e- = 6e- 6F× 7e- = 42e- 48e- F F F S F F F + 2 24 pairs of e- - 6 pairs of e- 18 pairs of e-

More Related