Ch.10 - Molecular Shapes & Valence Bond TheoryWorksheetSee all chapters
All Chapters
Ch.1 - Intro to General Chemistry
Ch.2 - Atoms & Elements
Ch.3 - Chemical Reactions
BONUS: Lab Techniques and Procedures
BONUS: Mathematical Operations and Functions
Ch.4 - Chemical Quantities & Aqueous Reactions
Ch.5 - Gases
Ch.6 - Thermochemistry
Ch.7 - Quantum Mechanics
Ch.8 - Periodic Properties of the Elements
Ch.9 - Bonding & Molecular Structure
Ch.10 - Molecular Shapes & Valence Bond Theory
Ch.11 - Liquids, Solids & Intermolecular Forces
Ch.12 - Solutions
Ch.13 - Chemical Kinetics
Ch.14 - Chemical Equilibrium
Ch.15 - Acid and Base Equilibrium
Ch.16 - Aqueous Equilibrium
Ch. 17 - Chemical Thermodynamics
Ch.18 - Electrochemistry
Ch.19 - Nuclear Chemistry
Ch.20 - Organic Chemistry
Ch.22 - Chemistry of the Nonmetals
Ch.23 - Transition Metals and Coordination Compounds
Additional Problems
What is the bond order of He2+? a. 0 b. ½ c. 1 d. 1 ½ e. 2
Based on molecular orbital theory, the bond order of the H2 molecules is: a. 1 b. 2 c. 0 d. ½  e. 1.3
Based on molecular orbital theory, what is the bond order of the H 2 molecule? a) 1 b) 2 c) 0 d) 1/2 e) 1.3
As the bond order of a bond decreases, its bond energy __________ and its bond length __________. a) increases, increases b) decreases, decreases c) increases, decreases d) decreases, increases e) It is not possible to predict these trends.
Which of the following structures is lower in energy?
The bond order of N22+is 2.5 2 1.5 3  
Use the molecular orbital diagram shown to determine which of the following is   most stable. A) N22+  B) B2 C) B22+ D) C22- E) C22+  
What is the bond order for the NO bond in NO 3 – ? A. -1                  B. 1               C. 1.33           D. 2             E. 4
What is the bond order of Cl 2+ ?
Use the molecular orbital diagram shown below to determine which of the following diatomic species has the highest bond order.   a.  F22⁻      b.  F22⁺          c.  O22⁺          d.  F2               e.  Ne22⁺
Which of the following compounds would be expected to have the longest N-O bonds? 1. NO 2. they will all be the same 3. NO3- 4. NO2-
What are the relationships among bond order, bond length, and bond energy?
What is the physical basis for the VSEPR model?
When applying the VSEPR model, we count a double or triple bond as a single electron domain. Why is this justified?
Carbon monoxide, CO, is isoelectronic to N2.Assume that the diagram in the first figure that described NO can also be used to describe the MOs of CO. What is the predicted bond order for CO?
The phosphorus trihalides (PX3) show the following variation in the bond angle X-P-X: PF3, 96.3 ; , 100.3 PCl3 ; , 101.0 ; { m Pl_3}, 102.0 Pl3 . The trend is generally attributed to the change in the electronegativity of the halogen.Assuming that all electron domains are the same size, what value of the X-P-X angle is predicted by the VSEPR model?
The phosphorus trihalides (PX3) show the following variation in the bond angle X-P-X: PF3, 96.3 ; , 100.3 PCl3 ; , 101.0 ; { m Pl_3}, 102.0 Pl3 . The trend is generally attributed to the change in the electronegativity of the halogen.Using the VSEPR model, explain the observed trend in X-P-X angle as the electronegativity of X changes.
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.What is the bond order in Sc2?
In the most accepted picture of HF, all the other atomic orbitals on fluorine move over at the same energy into the molecular orbital energy level diagram for HF. These are called "nonbonding orbitals". Using the energy level diagram for HF, calculate the bond order. (Nonbonding electrons do not contribute to bond order.)
Use molecular orbital theory to predict whether or not each of the following molecules or ions should exist in a relatively stable form.H2 2 -
Use molecular orbital theory to predict whether or not each of the following molecules or ions should exist in a relatively stable form.Ne2
Use molecular orbital theory to predict whether or not each of the following molecules or ions should exist in a relatively stable form.He2 2 +
Use molecular orbital theory to predict whether or not each of the following molecules or ions should exist in a relatively stable form.F2 2 -
Which statement best describes an O 3 molecule?i) Each atom in ozone is connected to another atom by a bond having a bond order of 1.5.ii) The double bond in ozone switches back and forth between the two outer oxygen atoms.iii) An ozone molecule contains one single bond and one double bond.
What is the bond order of Li2−? Is Li2− paramagnetic or diamagnetic?
Compared to the H−H bond in H 2, the H−H bond in H 2− is expected to be which of the following?a. longer and strongerb. longer and weakerc. shorter and weakerd. shorter and strongere. the same length and strength
Draw a molecular orbital diagram for Ar2+. This ion has been observed in the gas phase. Calculate bond order and describe how the bond distance in this ion would differ from that in Cl2.
Rank the following diatomic species of oxygen in order of bond length and bond strength.
The bond order for a molecule is the number of bonds between a pair of atoms. For example, for the oxygen molecule, O = O, the bond order is two; for the hydrogen molecule, H - H, the bond order is one. Bond order indicates the strength of the bond. Consider the four resonating structures of the phosphate ion: Calculate the average bond order for a P - O bond (such as the one shown in blue) in a phosphate ion. Express your answer numerically as a decimal or improper fraction.
Given the molecular orbital diagram below, determine the bond order for nitrogen gas, N2 A. 0               B. 1                    C. 2                  D. 3                E. 4
Construct the molecular orbital diagram for He2 + and then identify the bond order.
Draw the Lewis structure of PF 3.a) How many shared pairs are in this molecule?b) How many lone pairs are on the phosphorus atom?c) What is the P/F bond order?
Use an MO diagram to find the bond order and predict whether H 2− exists.
Which statement best describes an O 3 molecule?a) Each atom in ozone is connected to another atom by a bond having a bond order of 1.5.b) The double bond in ozone switches back and forth between the two outer oxygen atoms.c) An ozone molecule contains one single bond and one double bond.
Complete the MO energy level diagram for O22-. a. Fill in the electrons using arrows (↑ and/or ↓) for the atomic and molecular orbitals. b. Designate all the energy levels (i.e., σ2s*, π2p, σ2s, etc.)  c. Calculate the bond order for O22-. d. Is O2 2- a paramagnetic or diamagnetic chemical species?
What is the bond order of B2-?Is B2- paramagnetic or diamagnetic?a. paramagneticb. diamagneticc. Neither
One of the excited states of a C2 molecule has the electron configuration:  (σ1s)2(σ1s*)2(σ2s)2(σ2s*)1(π2p)4(σ2p)1 i) What is the bond order of C2 in this excited state? ii) What is the bond order of C2 in the ground state? iii) How does the bond length in this excited state compare to that in the ground state?
Construct the molecular orbital diagram for H 2- and then identify the bond order.
What charge would be needed on F 2 to generate an ion with a bond order of 2?
You may want to reference (Pages 338 - 393) Chapter 9 while completing this problem.Place the following molecules and ions in order from smallest to largest bond order: H2+, B2, N2+, F2+, and Ne2.
Using the MO diagram, predict the bond order for the stronger bond pair:(a) B2 or B2+
Using the MO diagram, predict the bond order for the stronger bond pair:(b) F2 or F2+
Using the MO diagram, predict the bond order for the stronger bond pair:(c) O2 or O22+
Using the MO diagram, predict the bond order for the stronger bond pair:(d) C2+ or C2−
The following is part of a molecular orbital energy-level diagram for MOs constructed from 1s atomic orbitals.What is the bond order of the molecule or ion?
You may want to reference (Pages 371 - 382)Section 9.8 while completing this problem.Place the following molecular ions in order from smallest to largest bond order: C22+, N2–, O2–, and F2–.
Apply molecular orbital theory to determine the bond order in C2.
Apply molecular orbital theory to predict which species has the strongest bond.a) N2b) N2–c) N2+d) All bonds are equivalent according to molecular orbital theory.
You may want to reference (Pages 368 - 371)Section 9.7 while completing this problem.How many of the following molecules and ions have a bond order of 1/2large{frac {1}{2}}: H2, H2+, H2–, and He22+?
The results of a molecular orbital calculation for H2O are shown here. Examine each of the orbitals and classify them as bonding, antibonding, or nonbonding. Assign the correct number of electrons to the energy diagram. According to this energy diagram, is H2O stable? Explain.
The results of a molecular orbital calculation for NH3 are shown here. Examine each of the orbitals and classify them as bonding, antibonding, or nonbonding. Assign the correct number of electrons to the energy diagram. According to this energy diagram, is NH3 stable? Explain. 
Use an MO diagram and the bond order you obtain from it to answer the question: Is Be2+ stable?
Use an MO diagram and the bond order you obtain from it to answer the question: Is Be2+ diamagnetic?
Use an MO diagram and the bond order you obtain from it to answer the question: What is the outer (valence) electron configuration of Be2+?
Use an MO diagram and the bond order you obtain from it to answer the question: Is O2− stable?
According to molecular orbital theory, would Be2+ be expected to exist?
Use an MO diagram and the bond order you obtain from it to answer the question: Is O2− paramagnetic?
Use an MO diagram and the bond order you obtain from it to answer the question: What is the outer (valence) electron configuration of O2−?
Use MO diagrams to rank C 2−, C2, and C2+ in order of increasing bond energy.
Use MO diagrams to rank C 2−, C2, and C2+ in order of increasing bond length.
Use MO diagrams to rank B 2+ , B2, and B2− in order of decreasing bond energy.
Use MO diagrams to rank B 2+ , B2, and B2− in order of decreasing bond length.
In each case indicate whether the addition of an electron to the ion would increase or decrease the bond order of the species.
In addition to ammonia, nitrogen forms three other hydrides: hydrazine (N 2H4), diazene (N2H2), and tetrazene (N4H4).(a) Use Lewis structures to compare the strength, length, and order of the nitrogen-nitrogen bonds in hydrazine
Use molecular orbital theory to predict the bond order in H2+.
Is the H2+ bond a stronger or weaker bond than the H2 bond?
Do you expect the bond in the N2+ ion to be stronger or weaker than the bond in the N2 molecule?
Determine the bond order for the N2+ ion.
Apply molecular orbital theory to determine the bond order of Ne2.
The diatomic molecule OH exists in the gas phase. The bond length and bond energy have been measured to be 97.06 pm and 424.7 kJ/mol, respectively. Assume that the OH molecule is analogous to the HF molecule discussed in the chapter and that molecular orbitals result from the overlap of a lowerenergy pz orbital from oxygen with the higher-energy 1s orbital of hydrogen (the O—H bond lies along the z-axis). d. Estimate the bond order for OH.
Consider the H2+ ion. What is the bond order in H2+?
The diatomic molecule OH exists in the gas phase. The bond length and bond energy have been measured to be 97.06 pm and 424.7 kJ/mol, respectively. Assume that the OH molecule is analogous to the HF molecule discussed in the chapter and that molecular orbitals result from the overlap of a lowerenergy pz orbital from oxygen with the higher-energy 1s orbital of hydrogen (the O—H bond lies along the z-axis). e. Predict whether the bond order of OH + will be greater than, less than, or the same as that of OH. Explain.
Calculate the bond order in H2-.
In each of the following compounds, the C atoms form a single ring. Draw a Lewis structure for each molecule, identify cases for which resonance exists, and determine the carboncarbon bond order(s):(a) C3H4
In each of the following compounds, the C atoms form a single ring. Draw a Lewis structure for each molecule, identify cases for which resonance exists, and determine the carboncarbon bond order(s):(b) C3H6
In each of the following compounds, the C atoms form a single ring. Draw a Lewis structure for each molecule, identify cases for which resonance exists, and determine the carboncarbon bond order(s):(c) C4H6
In each of the following compounds, the C atoms form a single ring. Draw a Lewis structure for each molecule, identify cases for which resonance exists, and determine the carboncarbon bond order(s):(d) C4H4
Use the molecular orbital diagram shown to determine which of the following is most stable. a. F22+ b. Ne22+ c. F22- d. O22+ e. F2
In each of the following compounds, the C atoms form a single ring. Draw a Lewis structure for each molecule, identify cases for which resonance exists, and determine the carboncarbon bond order(s):(e) C6H6.
Perchlorates are powerful oxidizing agents used in fireworks, flares, and the booster rockets of space shuttles. Lewis structures for the perchlorate ion (ClO4−) can be drawn with all single bonds or with one, two, or three double bonds. Draw each of these possible resonance forms, use formal charges to determine the more important structure, and calculate its average bond order.
What is the bond order for a second-period diatomic molecule containing one electron in antibonding molecular orbitals and two electrons in bonding molecular orbitals?
You may want to reference (Pages 461 - 461)Section 10.8 while completing this problem.Use the MO diagrams to calculate the bond order for Li2+ and Li2–.
Using the molecular orbital energy ordering for second-row homonuclear diatomic molecules in which the π2p orbitals lie at higher energy than the σ2p, predict the bond order in a molecule or ion with each of the following numbers of total valence electrons (by drawing MO energy diagrams). Will the molecule or ion be diamagnetic or paramagnetic?Determine the bond order in a molecule or ion with 10 valence electrons.
Using the molecular orbital energy ordering for second-row homonuclear diatomic molecules in which the π2p orbitals lie at higher energy than the σ2p, predict the bond order in a molecule or ion with each of the following numbers of total valence electrons (by drawing MO energy diagrams). Will the molecule or ion be diamagnetic or paramagnetic?Determine the bond order in a molecule or ion with 12 valence electrons.
Using the molecular orbital energy ordering for second-row homonuclear diatomic molecules in which the π2p orbitals lie at higher energy than the σ2p, predict the bond order in a molecule or ion with each of the following numbers of total valence electrons (by drawing MO energy diagrams). Will the molecule or ion be diamagnetic or paramagnetic?Determine the bond order in a molecule or ion with 13 valence electrons.
Using the molecular orbital energy ordering for second-row homonuclear diatomic molecules in which the π2p orbitals lie at higher energy than the σ2p, predict the bond order in a molecule or ion with each of the following numbers of total valence electrons (by drawing MO energy diagrams). Will the molecule or ion be diamagnetic or paramagnetic?Determine the bond order in a molecule or ion with 14 valence electrons.
Calculate the bond order for an ion with this configuration: (σ2s)2 (σ*2s )2 (σ2px)2 (π2py, π2pz)4 (π*2py, π*2pz)3
According to MO theory, which of the following ions has the highest bond order? O2, O2– , O22–
Predict the valence electron molecular orbital configuration for the following, and state whether they will be stable or unstable ions.(a) Na22+
According to MO theory, which of the following ions has the highest bond energy? O2, O2– , O22–
According to MO theory, which of the following ions has the shortest bond length? O2, O2– , O22–
Predict the valence electron molecular orbital configuration for the following, and state whether they will be stable or unstable ions.(b) Mg22+
Predict the valence electron molecular orbital configuration for the following, and state whether they will be stable or unstable ions.(c) Al22+
Predict the valence electron molecular orbital configuration for the following, and state whether they will be stable or unstable ions.(d) Si22+
What is the bond order of Be2 −?
Predict the valence electron molecular orbital configuration for the following, and state whether they will be stable or unstable ions.(e) P22+
Predict the valence electron molecular orbital configuration for the following, and state whether they will be stable or unstable ions.(f) S22+
Predict the valence electron molecular orbital configuration for the following, and state whether they will be stable or unstable ions.(g) F22+
Predict the valence electron molecular orbital configuration for the following, and state whether they will be stable or unstable ions.(h) Ar22+
Determine the bond order of a member of the following group, and determine which member of this group is predicted by the molecular orbital model to have the strongest bond.(a) H2, H2+, H2−
Determine the bond order of a member of the following group, and determine which member of this group is predicted by the molecular orbital model to have the strongest bond.(b) O2, O22+, O22−
Determine the bond order of a member of the following group, and determine which member of this group is predicted by the molecular orbital model to have the strongest bond.(c) Li2, Be2+, Be2
Use the drawing of MO energy diagram to predict the bond order of Be2+ and Be2–. Do you expect Be2+ to exist in the gas phase?
Determine the bond order of a member of the following group, and determine which member of this group is predicted by the molecular orbital model to have the strongest bond.(d) F2, F2+, F2−
Use the drawing of MO energy diagram to predict the bond order of Be2+ and Be2–. Do you expect Be2– to exist in the gas phase?
Using the molecular orbital energy ordering for second-row homonuclear diatomic molecules in which the π2p orbitals lie at lower energy than the σ2p, predict the bond order in a molecule or ion with each of the following numbers of total valence electrons.(Use the drawing MO energy diagrams). Will the molecule or ion be diamagnetic or paramagnetic?Determine the bond order in a molecule or ion with 4 valence electrons.
Determine the bond order of a member of the following group, and determine which member of this group is predicted by the molecular orbital model to have the strongest bond.(e) N2, N2+, N2−
Using the molecular orbital energy ordering for second-row homonuclear diatomic molecules in which the π2p orbitals lie at lower energy than the σ2p, predict the bond order in a molecule or ion with each of the following numbers of total valence electrons.(Use the drawing MO energy diagrams). Will the molecule or ion be diamagnetic or paramagnetic?Determine the bond order in a molecule or ion with 6 valence electrons.
Using the molecular orbital energy ordering for second-row homonuclear diatomic molecules in which the π2p orbitals lie at lower energy than the σ2p, predict the bond order in a molecule or ion with each of the following numbers of total valence electrons.(Use the drawing MO energy diagrams). Will the molecule or ion be diamagnetic or paramagnetic?Determine the bond order in a molecule or ion with 8 valence electrons.
Using the molecular orbital energy ordering for second-row homonuclear diatomic molecules in which the π2p orbitals lie at lower energy than the σ2p, predict the bond order in a molecule or ion with each of the following numbers of total valence electrons.(Use the drawing MO energy diagrams). Will the molecule or ion be diamagnetic or paramagnetic?Determine the bond order in a molecule or ion with 9 valence electrons.
According to MO theory, which of the following has the highest bond order: C2, C2+, C2–?
One of the molecular orbitals of the H2– ion is sketched below:What is the bond order in the H2– ion?
What is the bond order of N 2+?
According to MO theory, which molecule or ion has the highest bond order? Highest bond energy? Shortest bond length? (Use the energy ordering of O2)a. O2, O2-1, O2-b. CO and CO+. 
Determine the bond order in a molecule or ion with: a. 10 valence electrons. b. 12 valence electrons. c. 13 valence electrons. d. 14 valence electrons.
a. What is the bond order of N 2+? Express the bond order numerically.  b. Is N2+ paramagnetic or diamagnetic?
What is the bond order of Li2 2+?
Use MO diagram to place C2-,C2 and C2+ in order of decreasing bond energy?
Determine the bond order for F2, F2+ and F2 -. Which molecule should be the most stable?
Draw the molecular orbital diagram for N2- ion, and calculate the bond order. Indicate if it is diamagnetic or paramagnetic.