1. Molecular
Geometry

2. Valence Shell Electron Pair Repulsion (VSEPR) Theory
Electron concentrations are arranged so as to be at maximum distance.
Why?
Electrons repel each other.

3. Number of Electron Concentrations
Ex: CH4 H C ×

4. Number of Electron Concentrations
Ex: CF2O O F C ×

5. all 4 bonded = tetrahedral
4 Regions of e− Conc.
all 4 bonded = tetrahedral
Ex: CH4 H C ×
Chemistry textbook, p. 169

6. 4 Regions of e− Conc. H N 3 bonded = pyramidal Ex: NH3 ×
Chemistry textbook, p. 167

7. 4 Regions of e− Conc. H O 2 bonded = bent 104.5° Ex: H2O ×
Chemistry textbook, p. 170

8. 4 Regions of e− Conc. H F 1 bonded = linear Ex: HF ×
Chemistry textbook, p. 170

9. 3 Regions of e− Conc. All 3 bonded = trigonal planar Ex: BI3
2 bonded = bent 120°
Ex: GeF2
1 bonded = linear
Ex: SO

10. 2 Regions of e− Conc. Both bonded = linear Ex: BeF2 1 bonded = linear
Ex: CO

11. # Regions # Bonds Shape 4 3 2 4 3 2 1 tetrahedral pyramidal
bent 109.5°
linear
trig. planar
bent 120°
linear
linear

12. Question
How many regions of electron concentration are in this molecule? 1 2 3 4
Not enough information H N ×

13. H N Question How many bonds are in this molecule? 1 2 3 4
Not enough information H N ×

14. Bonding & Electronegativity
When two atoms of the same element bond, they share e− equally, because they have the same electronegativity.

15. Bonding & Electronegativity
If atoms with different electronegativities bond, the e− are unequally shared.

16. polar covalent bonds
bonds in which electrons are shared unevenly between atoms having different electronegativities

17. Polar Covalent Bonds
The greater the difference in electronegativity, the more unequal the sharing is.
If the difference in electronegativity is great enough, the sharing is so unequal that the bonds are called ionic bonds.

18. Polar Covalent Bonds
They are called polar because the unequal attraction causes the ends to be partially charged.
Charged ends are called poles.

19. The arrow points towards the negative side of the polar molecule.
Polar Covalent Bonds δ+ δ− Cl H
The arrow points towards the negative side of the polar molecule.

20. dipole moment
a measure of the amount of polarity (unequal sharing) of the entire molecule

21. p. 173 of Chemistry textbook (BJU Press)
Credit: Spartan software

22. p. 173 of Chemistry textbook (BJU Press)
Credit: Spartan software

23. p. 173 of Chemistry textbook (BJU Press)
Credit: Spartan software

24. p. 173 of Chemistry textbook (BJU Press)
Credit: Spartan software

25. Polar Molecules Occur when there are polar bonds UNLESS:
A molecule is symmetrical.
All outer electronegativities are the same.

26. CO2

27. H2S

28. ClBr

29. chemoreception
the physical and chemical response of a sensory organ to the presence of a chemical
Example: sense of smell of volatile chemicals

30. Bonding Models VB vs. MO Neither is perfect.
Use the one that works best.