Textbook Question
For each of the following ions of nitrogen and oxygen, write a single Lewis structure that obeys the octet rule, and calculate the oxidation numbers and formal charges on all the atoms: c. NO2+.
Ch.8 - Basic Concepts of Chemical Bonding
Chapter 8, Problem 57
Predict the ordering, from shortest to longest, of the bond lengths in CO, CO2, and CO32- .
Verified step by step guidance1
Identify the types of bonds in each molecule or ion. CO has a triple bond, CO2 has two double bonds between carbon and oxygen, and CO32- (carbonate ion) has resonance structures typically represented with one double bond and two single bonds between carbon and oxygen.
Recall that generally, triple bonds are shorter than double bonds, and double bonds are shorter than single bonds due to the increasing number of shared electrons pulling the bonded atoms closer together.
Consider the effect of resonance in CO32-. Resonance can cause the actual bond lengths to be an average of the different forms, potentially making the bonds in CO32- shorter than a typical single bond but not as short as a double bond.
Compare the bond types and the effects of resonance to predict the relative bond lengths. Since CO has a triple bond, it should have the shortest bond length. CO2 with double bonds should have a longer bond length than CO but shorter than CO32-.
Order the molecules and ion from shortest to longest bond length based on the analysis: CO (shortest), CO2, CO32- (longest).
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Bond Length
Bond length is the distance between the nuclei of two bonded atoms. It is influenced by the type of bond (single, double, or triple) and the size of the atoms involved. Generally, shorter bonds correspond to stronger interactions between atoms, while longer bonds indicate weaker interactions.
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Average Bond Order
Bond Order
Bond order refers to the number of chemical bonds between a pair of atoms. It is calculated as the difference between the number of bonding and antibonding electrons divided by two. Higher bond orders typically result in shorter bond lengths due to increased electron density between the nuclei, leading to stronger attractions.
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Resonance Structures
Resonance structures are different ways of drawing the same molecule that illustrate the delocalization of electrons. In molecules like CO3^2-, resonance indicates that the actual bond lengths are an average of the different structures. This delocalization can affect bond lengths, making them longer than expected for a single bond but shorter than for a double bond.
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Related Practice
Textbook Question
(b) With what allotrope of oxygen is it isoelectronic?
Textbook Question
Consider the formate ion, HCO2-, which is the anion formed when formic acid loses an H+ ion. The H and the two O atoms are bonded to the central C atom. (b) Are resonance structures needed to describe the structure?
Textbook Question
Consider a Lewis structure for SO3 that satisfies the octet rule. Which of the following statements is or are true?
i. SO3 has three equivalent resonance structures.
ii. There are one shorter and two longer S—O bond lengths in SO3.
iii. The S atom in SO3 has a nonzero formal charge.
Textbook Question
Which of the following statements about benzene, C6H6, is or are true?
i. Benzene has two equivalent resonance structures.
ii. There are no nonbonding pairs in the Lewis structure for benzene.
iii. Benzene has three short and three long C—C bonds.
Textbook Question
b. Which of these compounds or ions is an exception to the octet rule: nitrogen dioxide, borohydride (BH4−), borazine (B3N3H6 which is analogous to benzene with alternating B and N in the ring), or boron trichloride?