Chapter 8

A compound with the formula \(\mathrm{Cl}_{2} \mathrm{O}_{6}\) decomposes to a mixture of \(\mathrm{ClO}_{2}\) and \(\mathrm{ClO}_{4} .\) Draw two Lewis structures for \(\mathrm{Cl}_{2} \mathrm{O}_{6}:\) one with a chlorine-chlorine bond and one with a Cl- \(\mathrm{O}-\) Cl arrangement of atoms. Draw a Lewis structure for \(\mathrm{ClO}_{2}\) $$\mathrm{Cl}_{2} \mathrm{O}_{6} \rightarrow \mathrm{ClO}_{2}+\mathrm{ClO}_{4}$$

A compound consisting of chlorine and oxygen, \(\mathrm{Cl}_{2} \mathrm{O}_{7}\) decomposes by the following reaction: $$ \mathrm{Cl}_{2} \mathrm{O}_{7} \rightarrow \mathrm{ClO}_{4}+\mathrm{ClO}_{3} $$ a. Draw two Lewis structures for \(\mathrm{Cl}_{2} \mathrm{O}_{7}\) : one with a chlorine-chlorine bond and one with a \(\mathrm{Cl}-\mathrm{O}-\mathrm{Cl}\) arrangement of atoms. b. Draw a Lewis structure for \(\mathrm{ClO}_{3}\)

Draw all resonance forms for the molecules NSF and HBS where \(S\) and \(B\) are the central atoms, respectively. Include possible ionic structures for NSF.

The heavier group 16 elements can expand their valence shell. The \(\mathrm{TeOF}_{6}^{2-}\) anion was first prepared in \(1993 .\) Draw the Lewis structure for \(\operatorname{Te} \mathrm{OF}_{6}^{2-}\).

Sulfur in the Environment Sulfur is cycled in the environment through compounds such as dimethyl sulfide \(\left(\mathrm{CH}_{3} \mathrm{SCH}_{3}\right),\) hydrogen sulfide \(\left(\mathrm{H}_{2} \mathrm{S}\right),\) and sulfite and sulfate ions. Draw Lewis structures for these four species. Are expanded valence shells needed to minimize the formal charges for any of these species?

Consider a hypothetical structure of ozone that is cyclic (the atoms form a ring) such that its three O atoms are at the corners of a triangle. Draw the Lewis structure for this molecule.

Bond lengths and electrostatic potential mapping provide experimental evidence about covalent bonds present in a molecule. Which of these would help characterize the bonding in a compound with the formula \(\mathrm{A}_{2} \mathrm{X}\) in terms of the following? a. distinguishing between these two bonding patterns: \(\mathrm{X}-\mathrm{A}-\mathrm{A}\) and \(\mathrm{A}-\mathrm{X}-\mathrm{A}\) b. distinguishing between these resonance forms: \(\mathrm{A}-\mathrm{X} \equiv \mathrm{A}, \mathrm{A}=\mathrm{X}=\mathrm{A},\) and \(\mathrm{A} \equiv \mathrm{X}-\mathrm{A}\)

Explosive Cation The highly explosive \(\mathrm{N}_{5}^{+}\) cation was first isolated in 1999 by reaction of \(\mathrm{N}_{2} \mathrm{F}^{+}\) with \(\mathrm{HN}_{3}:\) $$ \mathrm{N}_{2} \mathrm{F}^{+}+\mathrm{HN}_{3} \rightarrow \mathrm{N}_{5}^{+}+\mathrm{HF} $$ Draw the Lewis structures for the reactants and products, including all resonance forms.

Jupiter's Atmosphere The ionic compound NH_4 SH was detected in the atmosphere of Jupiter (Figure P8.159) by the Galileo space probe in \(1995 .\) Draw the Lewis structure for \(\mathrm{NH}_{4} \mathrm{SH}\). Why couldn't there be a covalent bond between the nitrogen and sulfur atoms, making \(\mathrm{NH}_{4} \mathrm{SH}\) a molecular compound?

Antacid Tablets Antacids commonly contain calcium carbonate, magnesium hydroxide, or both. Draw the Lewis structures for calcium carbonate and magnesium hydroxide.

An allotrope of nitrogen, \(\mathrm{N}_{4},\) was reported in \(2002 .\) The compound has a lifetime of \(1 \mu \mathrm{s}\) at \(298 \mathrm{K}\) and was prepared by adding an electron to \(\mathrm{N}_{4}^{+}\). Because the compound cannot be isolated, its structure is unconfirmed experimentally. a. Draw the Lewis structures for all the resonance forms of linear \(\mathrm{N}_{4}\). (Linear means that all four nitrogens are in a straight line.) b. Assign formal charges, and determine which structure is the best description of \(\mathrm{N}_{4}\) c. Draw a Lewis structure for a ring (cyclic) form of \(\mathrm{N}_{4}\) and assign formal charges.

Scientists have predicted the existence of \(\mathrm{O}_{4}\) even though this compound has never been observed. However, \(\mathrm{O}_{4}^{2-}\) has been detected. Draw the Lewis structures for \(\mathrm{O}_{4}\) and \(\mathrm{O}_{4}^{2-}\).

Draw a Lewis structure for AlFCl,, the second product in the synthesis of \(\mathrm{Cl}_{2} \mathrm{O}_{2}\) in the following reaction: $$\mathrm{FClO}_{2}(g)+\mathrm{AlCl}_{3}(s) \rightarrow \mathrm{Cl}_{2} \mathrm{O}_{2}(g)+\mathrm{AlFCl}_{2}(s)$$

Draw Lewis structures for \(\mathrm{BF}_{3}\) and \(\left(\mathrm{CH}_{3}\right)_{2} \mathrm{BF}\). The \(\mathrm{B}-\mathrm{F}\) distance in both molecules is the same \((130 \mathrm{pm}) .\) Does this observation support the argument that all the boronfluorine bonds in \(\mathrm{BF}_{3}\) are single bonds?

Which of the following molecules and ions contains an atom with an expanded valence shell? (a) \(\mathrm{Cl}_{2} ;\) (b) \(\mathrm{ClF}_{3}\) (c) \(\mathrm{ClI}_{3} ;\) (d) \(\mathrm{ClO}^{-}\).

Which of the following molecules contains an atom with an expanded valence shell? (a) \(\mathrm{XeF}_{2} ;\) (b) \(\mathrm{GaCl}_{3} ;\) (c) \(\mathrm{ONF}_{3}\) (d) \(\mathrm{SeO}_{2} \mathrm{F}_{2}\).

A linear nitrogen anion, \(\mathrm{N}_{5}\), was isolated for the first time in 1999 a. Draw the Lewis structures for four resonance forms of linear \(\mathrm{N}_{5}^{-}\) b. Assign formal charges to the atoms in the structures in part (a), and identify the structures that contribute the most to the bonding in \(\mathrm{N}_{5}^{-}\). c. Compare the Lewis structures for \(\mathrm{N}_{5}^{-}\) and \(\mathrm{N}_{3}^{-} .\) In which ion do the nitrogen-nitrogen bonds have the higher average bond order?

The cation \(\mathrm{N}_{2} \mathrm{F}^{+}\) is isoelectronic with \(\mathrm{N}_{2} \mathrm{O}\). a. What does it mean to be isoelectronic? b. Draw the Lewis structure for \(\mathrm{N}_{2} \mathrm{F}^{+}\). (Hint: The molecule contains a nitrogen-nitrogen bond.) c. Which atom has the +1 formal charge in the structure you drew in part (b)? d. Does \(\mathrm{N}_{2} \mathrm{F}^{+}\) have resonance forms? e. Could the middle atom in the \(\mathrm{N}_{2} \mathrm{F}^{+}\) ion be a fluorine atom? Explain your answer.

Ozone Depletion Methyl bromide (CH \(_{3} \mathrm{Br}\) ) is produced naturally by fungi. Methyl bromide has also been used in agriculture as a fumigant, but this use is being phased out because the compound has been linked to ozone depletion in the upper atmosphere. a. Draw the Lewis structure for \(\mathrm{CH}_{3} \mathrm{Br}\). b. Which bond in \(\mathrm{CH}_{3} \mathrm{Br}\) is more polar, carbon-hydrogen or carbon-bromine?

Atoms of Xe have complete octets, yet the compound \(\mathrm{XeO}_{2}\) exists. How is this possible?

Free radicals increase in stability, and hence decrease in reactivity, if they have more than one atom in their structure that can carry the unpaired electron. a. Draw Lewis structures for the three free radicals formed from \(\mathrm{CF}_{2} \mathrm{Cl}_{2}\) in the stratosphere \(-\mathrm{ClO}, \mathrm{Cl},\) and \(\mathrm{CF}_{2} \mathrm{Cl}-\) and use this principle to rank them in order of reactivity. b. Free radicals are "neutralized" when they react with each other, forming an electron pair (a single covalent bond) between two atoms. This is called a termination reaction because it shuts down any reaction that was powered by the free radical. Predict the formula of the molecules that are produced when the chlorine free radical reacts with each of the free radicals in part (a).