12. Molecular Shapes & Valence Bond Theory

MO Theory: Homonuclear Diatomic Molecules

CHEMISTRY 101: Molecular Orbital Theory, Bond order, bond strength, magnetic properties

One of the molecular orbitals of the H2- ion is sketched below:
<img src="https://lightcat-files.s3.amazonaws.com/problem_images/4f2145ace2151bbf-1661338969072.jpg" alt="" />
(a) Is the molecular orbital a s or p MO? Is it bonding or
antibonding?

All molecules with polar bonds are polar.

The vectors of polar bonds can sum to zero.

A nonpolar molecule has only nonpolar bonds.

The shape of a molecule is important in determining the molecular polarity.

Correct, symmetric geometries can produce nonpolar molecules and asymmetric ones polar molecules.

The greater the difference in electronegativity between two atoms in a bond, the smaller the magnitude of polarity.

 The polarity of the molecule is affected by both bond polarity and molecular geometry. 

Which of the following statements is true about polarity?

At high temperatures, sulfur vapor is predominantly in the 
form of S21g2 molecules. 
(a) Assuming that the molecular orbitals for third-row diatomic 
molecules are analogous to those for second-row molecules, 
construct an MO diagram for the valence orbitals of S21g2.

Molecular Orbital Theory - Bonding & Antibonding MO - Bond Order

Look at the MO diagrams of corresponding neutral diatomic 
species in Figure 8.22, and predict whether each of the following 
ions is diamagnetic or paramagnetic. Diagrams for 
Li2 and C2 are similar to N2; Cl2 is similar to F2. 
(c) F2-

The Molecular Orbital Theory.

MO Theory: Homonuclear Diatomic Molecules Concept 1

(σ2s)2(σ*2s)2(π2p)4(σ2p)2

(σ2s)2(σ*2s)2(π2p)2(σ2p)2(π*2p)2

(σ3s)2(σ*3s)2(π3p)4(σ3p)2

(σ3s)2(σ*3s)2(π3p)2(σ3p)2(π*3p)2

Using a MO diagram, write the electron configuration for the P2 molecule<img class="fr-dib"src="https://static.studychannel.pearsonprd.tech/courses/general-chemistry/thumbnails/images/5db66095"style="width:300px;">

Many compounds of the transition-metal elements contain
direct bonds between metal atoms. We will assume
that the z-axis is defined as the metal–metal bond axis.
(d) Sketch the energylevel
diagram for the Sc2 molecule, assuming that only the
3d orbital from part (a) is important.

Molecular Orbital Diagrams of Homonuclear Diatomics

(c) With what neutral homonuclear diatomic
molecules are the NO+ and NO- ions isoelectronic
(same number of electrons)?

With what neutral homonuclear diatomic molecule is the NO- ion isoelectronic (same number of electrons)?

How would we describe a substance that contains only paired 
electrons and is weakly repelled by a magnetic field? Which 
of the following ions would you expect to possess similar 
characteristics: H2-, Ne2+, F2, O22 +?

Determine the number of electrons found in the π2p orbitals for the dioxygen dication, O22+.&nbsp;<img class="fr-dib"src="https://static.studychannel.pearsonprd.tech/courses/general-chemistry/thumbnails/images/8fc3c79c"style="width:300px;">

Consider the molecular orbitals of the P2 molecule. Assume
that the MOs of diatomics from the third row of the periodic
table are analogous to those from the second row. (a) Which
valence atomic orbitals of P are used to construct the MOs of
P2?

Consider the molecular orbitals of the P2 molecule. Assume
that the MOs of diatomics from the third row of the periodic
table are analogous to those from the second row. (c) For the P2 molecule,
how many electrons occupy the MO in the figure? 
<img src="https://lightcat-files.s3.amazonaws.com/problem_images/0274d1bc0c00fed2-1661276744251.jpg" alt="" />

Consider the H2+ ion. (a) Sketch the molecular orbitals of 
the ion and draw its energy-level diagram.

Introduction to Molecular Orbital Theory

Molecular Orbital (MO) Diagram for O2(2-)

MO Theory: Homonuclear Diatomic Molecules Example 1

The vectors of the polar bonds do not sum to zero.

Correct, the linear geometry results in a cancellation of the vectors of the polar bonds.

 Draw the Lewis structure, determine the geometry and the see if bond dipole vectors do or do not sum to zero. 

Which of the following molecules is nonpolar?

Consider the H2+ ion. (b) How many electrons are there in the H2+ ion?

Examples of s-p Mixing in Molecular Orbital Theory

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1. Intro to General Chemistry

2. Atoms & Elements

3. Chemical Reactions

4. BONUS: Lab Techniques and Procedures

5. BONUS: Mathematical Operations and Functions

6. Chemical Quantities & Aqueous Reactions

7. Gases

8. Thermochemistry

9. Quantum Mechanics

10. Periodic Properties of the Elements

11. Bonding & Molecular Structure

13. Liquids, Solids & Intermolecular Forces

14. Solutions

15. Chemical Kinetics

16. Chemical Equilibrium

17. Acid and Base Equilibrium

18. Aqueous Equilibrium

19. Chemical Thermodynamics

20. Electrochemistry

21. Nuclear Chemistry

22. Organic Chemistry

23. Chemistry of the Nonmetals

24. Transition Metals and Coordination Compounds

[BOOK CHEM] Clutch Version

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.

Valence Shell Electron Pair Repulsion Theory

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