Lecture06222

33 %
67 %
Information about Lecture06222

Published on July 23, 2008

Author: uladzimir

Source: slideshare.net

Description

a supplemental resource for students

The Shapes of Molecules: Arrangement and Polarity Lecture 6

Microworld is not plain.

Microworld goes 3D! Let us visualize.

Valence Shell Electron-Pair Repulsion Theory (I): Each group of valence electrons around a central atom is located as far away as possible from the others in order to minimize repulsions. These repulsions maximize the space that each object attached to the central atom occupies.

Each group of valence electrons around a central atom is located as far away as possible from the others in order to minimize repulsions.

These repulsions maximize the space that each object attached to the central atom occupies.

The central atom and the valence electrons

Valence Shell Electron-Pair Repulsion Theory (II): The result is five electron-group arrangements of minimum energy seen in a large majority of molecules and polyatomic ions. The electron-groups are defining the object arrangement, but the molecular shape is defined by the relative positions of the atomic nuclei.

The result is five electron-group arrangements of minimum energy seen in a large majority of molecules and polyatomic ions.

The electron-groups are defining the object arrangement, but the molecular shape is defined by the relative positions of the atomic nuclei.

Valence Shell Electron-Pair Repulsion Theory (III): Because valence electrons can be bonding or nonbonding, the same electron-group arrangement can give rise to different molecular shapes.

Because valence electrons can be bonding or nonbonding, the same electron-group arrangement can give rise to different molecular shapes.

Linear electron-group arrangement

Trigonal planar arrangement

The same electron-group arrangement may lead to different molecular shapes.

Tetrahedral arrangement, tetrahedral shape

Tetrahedral arrangement, trigonal pyramidal shape

Tetrahedral arrangement, bent shape

Trigonal bipyramidal arrangement

Octahedral arrangement

A sample problem on predicting molecular shapes with two, three, or four electron groups.

A sample problem on predicting molecular shapes with five or six electron groups.

A sample problem on predicting molecular shapes with more than one central atom.

Both shape and bond polarity determine molecular polarity.

A sample problem on predicting the polarity of molecules.

THE END

Add a comment

Related presentations