VSEPR and Molecular Geometry

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Slide 1

VSEPR and Molecular Geometry

Hemoglobin

Slide 2

Models

Models are attempts to explain how nature operates on the microscopic level based on experiences in the macroscopic world.

Models can be physical as with this DNA model

Models can be mathematical

Models can be theoretical or philosophical

Slide 3

Fundamental Properties of Models

A model does not equal reality.

Models are oversimplifications, and are therefore often wrong.

Models become more complicated as they age.

We must understand the underlying assumptions in a model so that we don’t misuse it.

Slide 4

VSEPR Model

The structure around a given atom is determined principally by minimizing electron pair repulsions.

(Valence Shell Electron Pair Repulsion)

Slide 5

Predicting a VSEPR Structure

Draw Lewis structure.

Put pairs as far apart as possible.

Determine positions of atoms from the way electron pairs are shared

Determine the name of molecular structure from positions of the atoms.

Slide 6

Steric Number

1

1 atom bonded to another atom

Slide 7

Steric Number 2

2 atoms, or lone electron pairs, or a combination of the two, bonded to a central atom.

Slide 8

Steric Number 3

3 atoms, or lone electron pairs, or a combination of the two, bonded to a central atom.

Slide 9

Steric Number 4

4 atoms, or lone electron pairs, or a combination of the two, bonded to a central atom.

Slide 10

Steric Number 5

5 atoms, or lone electron pairs, or a combination of the two, bonded to a central atom.

Slide 11

Steric Number 6

6 atoms, or lone electron pairs, or a combination of the two, bonded to a central atom.

Slide 12

Steric Number 7

7 atoms, or lone electron pairs, or a combination of the two, bonded to a central atom.