12. Molecular Shapes & Valence Bond Theory

Valence Shell Electron Pair Repulsion Theory

VSEPR Theory: Determining the 3D Shape of Molecules

VSEPR Theory

Draw sketches illustrating the overlap between the following
orbitals on two atoms: (a) the 2s orbital on each atom

Valence Shell Electron Pair Repulsion Theory Concept 1

Valence Shell Electron Pair Repulsion Theory Concept 2

A series of anions is shown below:
<img src="https://lightcat-files.s3.amazonaws.com/problem_images/8afd873bf8083ffa-1665589175337.jpg" alt="" />
The anion on the far right is called “BARF” by chemists, as
its common abbreviation sounds similar to this word.
(a) What is the central atom and the number of electronpair domains around the central atom in each of these
anions?

Valence Shell Electron Pair Repulsion Theory Example 1

Valence Shell Electron Pair Repulsion Theory Example 2

VSEPR

How would you expect the extent of overlap of the bonding
atomic orbitals to vary in the series IF, ICl, IBr, and I2?
Explain your answer.

VSEPR Theory and Molecular Geometry

VSEPR Theory: Introduction

2p orbital of C and 1s orbital of H

Some of the orbitals of carbon are hybridized.

sp orbital of C and 1s orbital of H

Correct, sp is characteristic of carbon atom involved in triple bonds.

sp2 orbital of C and 1s orbital of H

Carbon atoms involved in triple bonds use an s and p orbital in hybridization.

sp3 orbital of C and 1s orbital of H

2s orbital of C and 1s orbital of H

 Single bonds can form from the overlap of hybridized or unhybridized orbitals or one of each. 

What two orbitals are participating in the overlap region that is part of the &#963; bond between the carbon and hydrogen atoms in acetylene? <img src="https://media.pearsoncmg.com/ph/esm/esm_tro_chemistry_6/msa/content/practice-quiz/img/tro_pq_c11q13.jpg" alt="Molecule showing, from left to right, a H atom singly bonded to a C atom which is bonded to another C atom by a triple bond. The second C atom is singly bonded to a H atom." class="block">

Draw sketches illustrating the overlap between the following
orbitals on two atoms: (b) the 2pz orbital on each atom (assume both atoms are on the z-axis)

Each of the following counts as a single electron group:  a lone pair, a single bond, a double bond, a triple bond, and a single electron.

All of these are counted as single electron group.

The geometry of the electron groups is determined by minimizing their repulsions.

This is the factor that determines the basic geometry.

The number of electron groups can be determined from the Lewis structure of the molecule.

Lewis structures serve as the starting point for VSEPR prediction of molecular geometry.

Bond angles can vary from the idealized angles because lone pairs of electrons take up less space than bonding groups.

Correct, lone pairs occupy more space due to stronger electrostatic repulsions.

The geometry of a molecule is determined by the number of electron groups on the central atom.

This is the factor that is basic to the determination of geometry.

 Review the basic premises of VSEPR theory. 

Which of the following statements is false about VSEPR theory?

VSEPR Theory - Basic Introduction

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[BOOK CHEM] Clutch Version

MO Theory: Homonuclear Diatomic Molecules

Homonuclear Diatomic Molecules are composed of 2 identical elements bonded together.

Equatorial and Axial Positions

Covalent compounds with 5 or 6&nbsp;electron groups have equatorial and axial positions for surrounding elements

MO Theory: Heteronuclear Diatomic Molecules

Heteronuclear Diatomic Molecules are composed of 2 different elements bonded together.

Bond Angles

Bond Angles&nbsp;result from surrounding elements and lone pairs around the central element positioning themselves at an optimal distance.&nbsp;

Molecular Orbital Theory

Molecular Orbital Theory&nbsp;allows us to predict the distribution of electrons within a molecule.&nbsp;

MO Theory: Bond Order

Molecular Orbital Diagrams can be used to determine the bond order of a molecule.

Electron Geometry

The simplest system for geometrical shapes that focuses on the number of electron groups around the central atom.

Hybridization

How would an&nbsp;s orbital combine with a p orbital to form a covalent bond? The answer is through hybridization where a hybrid&nbsp;oribital is formed.&nbsp;

Molecular Geometry

True Shape of Molecules that takes into account differences&nbsp;in repulsion between lone pairs and surrounding elements.

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