1. Molecular Geometry
Using VSEPR

2. VSEPR Valence Shell Electron Pair Repulsion
OK smart guy/gal what’s it mean?

3. Meaning The valence electrons pairs repel each other.
Determines the geometry or shape of the molecule.
Electron pairs will be as far away from each other as possible…

4. Steps for determining molecular shape
Determine the number of valence e- pairs (or groups) around the central atom.
Determine the number of valence e- pairs that are bonding…
Chose the geometry that allows the greatest distance between electron pairs.

5. Lewis Diagram CH4 How many valence e- pairs around central atom?
How many bonding pairs?
How far away from each other can they get????

6. Tetrahedral geometry Ex. CH4 4 pairs v. e- 4 pairs v. e- bonding
Note that the bond
Angle is greater than
900 its

8. Lewis diagram NH3 How many v e- pairs around central atom?
How many bonding
V e- pairs around central atom?

9. Trigonal-Pyramid 4 pairs v e- 3 pairs bonding Pyramid geometry
Like tetrahedral with
one atom removed.

10. Lewis Diagram H2S How many valence e- pairs around central atom?
How many bonding valence e- pairs around central atom?

11. Bent geometry 4 v e- pairs 2 pairs bonding Like tetrahedral with
two atoms removed

13. Lewis diagram CH2O Pairs of e- around the central atom?
3 …double or triple bonds must act as a single pair.
How many atoms bonded to central atom? 3…

14. Trigonal-Planar Triangular geometry 3 pairs of e- and 3 bonding.
1200 bond angle.

16. Lewis diagram CO2 e- pairs around the central atom?
TWO… double bonds act as one center of neg. charge.
atoms bonded to central atom?
TWO

17. CO2 Linear geometry
Two pairs of e-s or centers of neg. around the central atom.
1800 is the furthest away from each other they can be…remember, its repulsion!

19. Diagram ONF
How many Centers of negative charge surround the central atom?
Three.
How many atoms bonded to central atom?
Two

20. ONF has Bent geometry
The groups of electrons orient to the corners of a triangle. Only two atoms are bonded…this gives us bent or angular geometry.

21. 4 3 4 2 3 3 3 2 2 2 # groups of e-s # atoms bond
around center to center Geometry
4 4
4 2
3 3
3 2
2 2