1. Valence Shell Electron Pair Repulsion Theory
Planar triangular
Valence Shell Electron Pair Repulsion Theory
Tetrahedral
Trigonal bipyramidal
Octahedral

2. Molecular Structure
Molecular structure – the three-dimensional arrangement of atoms in a molecule

3. VSEPR Theory
VSEPR Theory (Valence Shell Electron Pair Repulsion Theory)
A model for describing the shapes of molecules whose main postulate is that the structure around a given atom is determined by minimizing the electron pair repulsion
Therefore, the electrons and elements bonded to the central atom want to be as far apart as possible

4. VSEPR Theory
Based on Lewis structures we can know the shape or “geometry” of molecules
The theory that predicts geometry (based on Lewis structures) is abbreviated VSEPR
VSEPR (pronounced “vesper”) stands for Valence Shell Electron Pair Repulsion
VSEPR, as the name suggests, predicts geometry based on the repulsion of electron pairs (in bonds or by themselves)
Electrons around the central nucleus repel each other. Thus, resulting structures have atoms maximally spread out (balloon demo)

5. VSEPR overview
The balloons represent electron clouds. At the end of each balloon will be a peripheral atom. The balloons meet at a central atom.
Each shape containing 2-6 peripheral atoms has a name (you will have to know these)
Sometimes the molecules are represented by AXY, where Y is the # of peripheral atoms
AX2 = linear
AX3 = planar triangular
AX4 = tetrahedral (tetra = 4 faces)
AX5 = trigonal bipyramidal (2 pyramids)
AX6 = octahedral (octa = 8 faces)
Work on handout (follow instructions on sheet)

6. VSEPR Steps Draw the Lewis structure for the molecule
Count the total number of things that are around the central atom to determine the electron pair geometry
Imagine that the lone pairs of electrons are invisible and describe the molecular shape

7. SORRY…
Yes…you must memorize the main shapes and bond angles

9. 2 Electron Pairs
If there are 2 things attached to the central atom, the shape is linear
Bond angle = 180°

10. VSEPR: Two Electron Pair
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11. Bonding in H2 Click in this box to enter notes.
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12. 3 Electron Pairs
If there are 3 electron pairs the shape will be trigonal planar
Bond angle = 120°

13. VSEPR: Three Electron Pair
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14. 3 electron pairs
Now imagine that you have 3 electron pairs, but one is just a lone pair (invisible) what would it look like then?

15. 4 electron pairs
If there are 4 electron pairs, the shape will be tetrahedral
Bond angle = 109.5°

16. VSEPR: Four Electron Pair
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17. 4 electron pairs
What if 1 of the electron pairs is a lone pair (invisible)? What would it look like then?
Trigonal Pyramidal

18. 4 electron pairs
What if there are 2 lone pairs (invisible)? What would it look like then?
bent

19. 5 electron pairs
If there are 5 electron pairs the shape will be Trigonal Bipyramidal
Bond angles = 90º & 180º

20. 5 electron pairs What is there is 1 lone pair (invisible)
Seesaw / Irregular Tetrahedral

21. 5 electron pairs
What is there are 2 lone pairs (invisible)
T-shaped

22. 6 pairs
Central atom has 6 total pairs = octahedral

23. 6 pairs
6 total pairs, 5 shared 1 unshared =
square pyramidal

24. VSEPR: Iodine Pentaflouride
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25. 6 pairs
6 total pairs, 4 shared, 2 unshared = square planar

26. VSEPR Click in this box to enter notes.
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28. All VSEPR shapes are based upon certain hybrids.
sp2 hybrids make bent, trigonal planar.
sp3 hybrids make water bent, trigonal pyramidal, and tetrahedral.

29. Hybridization: sp Click in this box to enter notes.
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30. Hybridization: sp2 Click in this box to enter notes.
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31. Hybridization: sp3 Click in this box to enter notes.
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