VSEPR theory

VSEPR theory (part 1)

by Monica Youssef

1. ​What is VSEPR?

2. ​Why VSEPR?

3. ​How VSPER?

​What is VSEPR?!

• VSEPR refers to Valence Shell Electron Pair Repulsion​.

• ​This theory states that "pairs of electrons (in bonds and in lone pairs) repel each other"

• ​Electrons try to be as far as possible from each others because that makes them more stable.

Multiple Choice

According to the VSEPR theory, ... want to ... each other.

• protons, repel

• protons, attract

• electrons, repel

• electrons, attract

Multiple Choice

According to VSEPR, molecules adjust their shapes to keep which of the following as far away as possible?

• Pairs of valence electrons
• Inner shell electrons
• Mobile Electrons
• Electrons closest to the nucleus

Why VSEPR is important?​

• ​​This repulsion between valence electrons affects the 3D shape of a molecule.

• ​Hence, this theory allows us to predict a molecule's 3D shape.

Multiple Choice

What is the VSEPR theory used to predict?

• Bond Strength
• Polarity
• Molecular Shape
• Electronegativity

​Linear

​Bent

​Bent

​Trigonal planner

​Tetrahedral

​Trigonal pyramidal

​How to predict the geometrical shape without having a model?!

​A molecule is given an AXE #, where:

• A is the central atom.

• X is a terminal atom.

• E is a nonbonding valence electron (a lone pair of electrons)

​Let's apply!

• ​A is the central atom = 1

• X is a terminal atom = 2​

• ​E is a lone pair = 2

• ​

• ​So AXE # of water = AX₂E₂

Multiple Choice

What is the AXE # of this molecule?

• AX₂

• AX₂E₂

• AX₂E

• AX₂E₄

Multiple Choice

What is the AXE # of this molecule?

• AX₂

• AX₂E₂

• AX₂E

• AX₂E₄

Multiple Choice

What is the AXE # of this molecule?

• AX

• AXE

• AX₃E

• AX₃