Chapter 8 Homework posted Lab Notes Today’s Topic: Bond Properties (Sec. 8.4- there is no 8.3!)...

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Chapter 8 Homework posted Lab Notes Today’s Topic: Bond Properties (Sec. 8.4- there is no 8.3!) Electron Distribution in Molecules (8.5) November 16, 2009
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Transcript of Chapter 8 Homework posted Lab Notes Today’s Topic: Bond Properties (Sec. 8.4- there is no 8.3!)...

Page 1: Chapter 8 Homework posted Lab Notes Today’s Topic: Bond Properties (Sec. 8.4- there is no 8.3!) Electron Distribution in Molecules (8.5) November 16, 2009.

•Chapter 8 •Homework posted•Lab Notes•Today’s Topic:

Bond Properties (Sec. 8.4- there is no 8.3!)

Electron Distribution in Molecules (8.5)

November 16, 2009

Page 2: Chapter 8 Homework posted Lab Notes Today’s Topic: Bond Properties (Sec. 8.4- there is no 8.3!) Electron Distribution in Molecules (8.5) November 16, 2009.

Rules for Drawing Lewis Structures

1. Write the skeletal structure2. Add up the total # of valence electrons3. Draw a bond between the central atom and each

surrounding atom4. Add lone pairs to the outer atoms to complete their

octets5. Add remaining electrons to central atom6. If central atom does not have an octet, “borrow”

electrons from other atoms (make double/triple bonds)- DO NOT ADD ELECTRONS (F and Cl do not form multiple bonds; C, N, O, P, and S do)

7. Sometimes you can’t complete an octet (B and Be)

Page 3: Chapter 8 Homework posted Lab Notes Today’s Topic: Bond Properties (Sec. 8.4- there is no 8.3!) Electron Distribution in Molecules (8.5) November 16, 2009.

Did you try this at home? Here’s the answer…

__# electrons__C = 4

H = 2 x 1 = 2Cl = 2 x 7 = 14

Total = 20

Page 4: Chapter 8 Homework posted Lab Notes Today’s Topic: Bond Properties (Sec. 8.4- there is no 8.3!) Electron Distribution in Molecules (8.5) November 16, 2009.

Organic Structures

CHCCHCH2

Page 5: Chapter 8 Homework posted Lab Notes Today’s Topic: Bond Properties (Sec. 8.4- there is no 8.3!) Electron Distribution in Molecules (8.5) November 16, 2009.

What can we do with Lewis Structures?

Bond Properties

1. Polarity

2. Bond Order

3. Bond Length

4. Bond Energy

Page 6: Chapter 8 Homework posted Lab Notes Today’s Topic: Bond Properties (Sec. 8.4- there is no 8.3!) Electron Distribution in Molecules (8.5) November 16, 2009.

Bond Types

Nonpolar Covalent

Polar Covalent

Ionic

Imagine theyare nuclei

Imagine this isa valence electron

Page 7: Chapter 8 Homework posted Lab Notes Today’s Topic: Bond Properties (Sec. 8.4- there is no 8.3!) Electron Distribution in Molecules (8.5) November 16, 2009.

Polarity

Electronegativity- The ability of an atom involved in a bond to attract electrons to itself Orbital energy, effective nuclear charge

Page 8: Chapter 8 Homework posted Lab Notes Today’s Topic: Bond Properties (Sec. 8.4- there is no 8.3!) Electron Distribution in Molecules (8.5) November 16, 2009.

Polarity

Electrons drawn closer to the more electronegative atom

Page 9: Chapter 8 Homework posted Lab Notes Today’s Topic: Bond Properties (Sec. 8.4- there is no 8.3!) Electron Distribution in Molecules (8.5) November 16, 2009.

Trend in Electronegativities

Page 10: Chapter 8 Homework posted Lab Notes Today’s Topic: Bond Properties (Sec. 8.4- there is no 8.3!) Electron Distribution in Molecules (8.5) November 16, 2009.

Bond Character: From Covalent to Ionic

Page 11: Chapter 8 Homework posted Lab Notes Today’s Topic: Bond Properties (Sec. 8.4- there is no 8.3!) Electron Distribution in Molecules (8.5) November 16, 2009.

In a C-O bond, which element will have a greater concentration of electron density?

1 2 3

15%5%

80%1. Carbon2. Oxygen3. Neither, they

will share the electrons equally

Page 12: Chapter 8 Homework posted Lab Notes Today’s Topic: Bond Properties (Sec. 8.4- there is no 8.3!) Electron Distribution in Molecules (8.5) November 16, 2009.

Bond Order

The number of bonding electron pairs between two atoms

Page 13: Chapter 8 Homework posted Lab Notes Today’s Topic: Bond Properties (Sec. 8.4- there is no 8.3!) Electron Distribution in Molecules (8.5) November 16, 2009.

Bond Length

Atom size

Bond order

Page 14: Chapter 8 Homework posted Lab Notes Today’s Topic: Bond Properties (Sec. 8.4- there is no 8.3!) Electron Distribution in Molecules (8.5) November 16, 2009.

Which bond is the longest?

1 2 3 4 5

12%

19%

45%

16%

8%

1. H - H2. H - Cl3. Cl - Cl4. Cl - Br5. Br - Br

Page 15: Chapter 8 Homework posted Lab Notes Today’s Topic: Bond Properties (Sec. 8.4- there is no 8.3!) Electron Distribution in Molecules (8.5) November 16, 2009.

Which bond is the shortest?

1 2 3 4

20%

36%40%

3%

1. N-N2. N=N3. NN4. All are the same

length