Chapter 7

Write the Lewis structures for the following molecules and polyatomic ions. In each case, the first atom is the central atom. (a) \(\mathrm{CCl}_{4}\) (b) \(\mathrm{NCl}_{3}\) (c) \(\mathrm{COCl}_{2}\) (d) \(\mathrm{SO}_{3}^{2-}\)

Oxalic acid, \(\mathrm{H}_{2} \mathrm{C}_{2} \mathrm{O}_{4}\), is a poisonous compound found in rhubarb leaves. Draw the Lewis structure for oxalic acid. There is a single bond between the two carbon atoms, each hydrogen atom is bonded to an oxygen atom, and each carbon is bonded to two oxygen atoms.

Radioastronomers have detected the isoformyl ion, \(\mathrm{HCO}^{\top}\), in outer space. Write the Lewis structure for this ion.

Dinitrogen pentoxide, \(\mathrm{N}_{2} \mathrm{O}_{5}\), when bubbled into water can form nitric acid. Its skeleton structure has no \(\mathrm{N}-\mathrm{N}\) or \(\mathrm{O}-\mathrm{O}\) bonds. Write its Lewis structure.

Glycine, an essential amino acid, has the formula \(\mathrm{NH}_{2} \mathrm{CH}_{2} \mathrm{COOH}\). Its skeleton structure has \(\mathrm{C}-\mathrm{C}\) and \(\mathrm{C}-\mathrm{N}\) bonds but \(\mathrm{no}\) N-O bonds. Write its Lewis structure.

Two different molecules have the formula \(\mathrm{C}_{2} \mathrm{H}_{2} \mathrm{Cl}_{2}\). Draw a Lewis structure for each molecule. (All the \(\mathrm{H}\) and \(\mathrm{Cl}\) atoms are bonded to carbon. The two carbon atoms are bonded to each other.)

Several compounds have the formula \(\mathrm{C}_{3} \mathrm{H}_{6} \mathrm{O}\). Write Lewis structures for two of these compounds where the three carbon atoms are bonded to each other in a chain. The hydrogen and the oxygen atoms are bonded to the carbon atoms.

Give the formula of a polyatomic ion that you would expect to have the same Lewis structure as (a) \(\mathrm{Cl}_{2}\) (b) \(\mathrm{H}_{2} \mathrm{SO}_{4}\) (c) \(\mathrm{CH}_{4}\) (d) \(\mathrm{GeCl}_{4}\)

Give the formula of a molecule that you would expect to have the same Lewis structure as (a) \(\mathrm{OH}^{-}\) (b) \(\mathrm{O}_{2}^{2-}\) (c) \(\mathrm{CN}^{-}\) (d) \(\mathrm{SO}_{4}^{2-}\)

Write a Lewis structure for (a) \(\mathrm{XeF}_{3}{\underline{\phantom{xx}}}^{+}\) (b) \(\mathrm{PCl}_{4}^{+}\) (c) \(\mathrm{BrF}_{5}\) (d) \(\mathrm{HPO}_{4}^{2-}(\) no \(\mathrm{P}-\mathrm{H}\) or \(\mathrm{O}-\mathrm{O}\) bonds \()\)

Write a Lewis structure for (a) \(\mathrm{P}_{2} \mathrm{O}_{7}^{4-}(\) no \(\mathrm{O}-\mathrm{O}\) or \(\mathrm{P}-\mathrm{P}\) bonds \()\) (b) \(\mathrm{HOBr}\) (c) \(\mathrm{NFBr}_{2}\) (d) \(\mathrm{IF}_{4}^{-}\)

Write reasonable Lewis structures for the following species, none of which follow the octet rule. (a) \(\mathrm{BeH}_{2}\) (b) \(\mathrm{CO}^{-}\) (c) \(\mathrm{SO}_{2}^{-}\) (d) \(\mathrm{CH}_{3}\)

Draw resonance structures for (a) \(\mathrm{Cl}-\mathrm{NO}_{2}\) (b) \(\mathrm{H}_{2} \mathrm{C}-\mathrm{N}-\mathrm{N}\) (c) \(\mathrm{SO}_{3}\)

The Lewis structure for hydrazoic acid may be written as (a) Draw two other resonance forms for this molecule. (b) Is

The oxalate ion, \(\mathrm{C}_{2} \mathrm{O}_{4}^{2-}\), has the skeleton structure (a) Complete the Lewis structure of this ion. (b) Draw three resonance forms for \(\mathrm{C}_{2} \mathrm{O}_{4}{\underline{\phantom{xx}}}^{2-}\), equivalent to the Lewis structure drawn in (a). (c) Is a resonance form of the oxalate ion?

Borazine, \(\mathrm{B}_{3} \mathrm{~N}_{3} \mathrm{H}_{6}\), has the skeleton Draw the resonance forms of the molecule.

What is the formal charge on the indicated atom in each of the following species? (a) sulfur in \(\mathrm{SO}_{2}\) (b) nitrogen in \(\mathrm{N}_{2} \mathrm{H}_{4}\) (c) each oxygen atom in ozone, \(\mathrm{O}_{3}\)

Predict the geometry of the following species: (a) \(\mathrm{SCO}\) (b) \(\mathrm{IBr}_{2}^{-}\) (c) \(\mathrm{NO}_{3}^{-}\) (d) \(\mathrm{RnF}_{4}\)

Predict the geometry of the following species: (a) \(\mathrm{SO}_{2}\) (b) \(\mathrm{BeCl}_{2}\) (c) \(\mathrm{SeCl}_{4}\) (d) \(\mathrm{PCl}_{5}\)

Predict the geometry of the following species: (a) \(\mathrm{KrF}_{2}\) (b) \(\mathrm{NH}_{2} \mathrm{Cl}\) (c) \(\mathrm{CH}_{2} \mathrm{Br}_{2}\) (d) SCN

Predict the geometry of the following species: (a) NNO (b) \(\mathrm{ONCl}\) (c) \(\mathrm{NH}_{4}{\underline{\phantom{xx}}}^{+}\) (d) \(\mathrm{O}_{3}\)

Predict the geometry of the following species: (a) \(\mathrm{SF}_{6}\) (b) \(\mathrm{BrCl}_{3}\) (c) \(\mathrm{SeCl}_{4}\) (d) \(\mathrm{IO}_{4}^{-}\)

Predict the geometry of the following species: (a) \(\mathrm{CIF}_{2}^{-}\) (b) \(\mathrm{SeF}_{5} \mathrm{Br}\) (c) \(\mathrm{SO}_{3}{\underline{\phantom{xx}}}^{2-}\) (d) \(\mathrm{BrO}_{2}^{-}\)

An objectionable component of smoggy air is acetylperoxide, which has the skeleton structure (a) Draw the Lewis structure of this compound. (b) Indicate all the bond angles.

In each of the following polyatomic ions, the central atom has an expanded octet. Determine the number of electron pairs around the central atom and the hybridization in (a) \(\mathrm{SF}_{2}{\underline{\phantom{xx}}}^{2-}\) (b) \(\mathrm{AsCl}_{6}^{-}\) (c) \(\mathrm{SCl}_{4}{\underline{\phantom{xx}}}^{2-}\)

Give the hybridization of the \(\mathrm{B}\) and \(\mathrm{N}\) atoms in borazine.

In which of the following molecules does the sulfur have an expanded octet? For those that do, write the Lewis structure. (a) \(\mathrm{SO}_{2}\) (b) \(\mathrm{SF}_{4}\) (c) \(\mathrm{SO}_{2} \mathrm{Cl}_{2}\) (d) \(\mathrm{SF}_{6}\)

Consider the dichromate ion. It has no metal-metal nor oxygenoxygen bonds. Write a Lewis structure for the dichromate ion. Consider chromium to have six valence electrons.

Given the following electronegativities $$ \mathrm{C}=2.5 \quad \mathrm{~N}=3.0 \quad \mathrm{~S}=2.6 $$ what is the central atom in CNS \(^{-}\) ?

Based on the concept of formal charge, what is the central atom in (a) HCN (do not include \(H\) as a possibility)? (b) \(\mathrm{NOCl}(\mathrm{Cl}\) is always a terminal atom)?

Describe the geometry of the species in which there are, around the central atom, (a) four single bonds, two unshared pairs of electrons. (b) five single bonds. (c) two single bonds, one unshared pair of electrons. (d) three single bonds, two unshared pairs of electrons. (e) two single bonds, two unshared pairs of electrons. (f) five single bonds, one unshared pair of electrons.

Consider the following molecules: \(\mathrm{SiH}_{4}, \mathrm{PH}_{3}, \mathrm{H}_{2} \mathrm{~S}\). In each case, a central atom is surrounded by four electron pairs. In which of these molecules would you expect the bond angle to be less than \(109.5^{\circ}\) ? Explain your reasoning.

Give the formula of an ion or molecule in which an atom of (a) \(\mathrm{N}\) forms three bonds using \(\mathrm{sp}^{3}\) hybrid orbitals. (b) \(\mathrm{N}\) forms two pi bonds and one sigma bond. (c) O forms one sigma and one pi bond. (d) C forms four bonds in three of which it uses \(s p^{2}\) hybrid orbitals. (e) Xe forms two bonds using \(\mathrm{sp}^{3} \mathrm{~d}^{2}\) hybrid orbitals.

In each of the following molecules, a central atom is surrounded by a total of three atoms or unshared electron pairs: \(\mathrm{SnCl}_{2}, \mathrm{BCl}_{3}, \mathrm{SO}_{2}\). In which of these molecules would you expect the bond angle to be less than \(120^{\circ}\) ? Explain your reasoning.

Explain the meaning of the following terms. (a) expanded octet (b) resonance (c) unshared electron pair (d) odd-electron species

A compound of chlorine and fluorine, \(\mathrm{ClF}_{x}\), reacts at about \(75^{\circ} \mathrm{C}\) with uranium to produce uranium hexafluoride and chlorine fluoride, ClF. A certain amount of uranium produced \(5.63 \mathrm{~g}\) of uranium hexafluoride and \(457 \mathrm{~mL}\) of chlorine fluoride at \(75^{\circ} \mathrm{C}\) and \(3.00 \mathrm{~atm} .\) What is \(x ?\) Describe the geometry, polarity, and bond angles of the compound and the hybridization of chlorine. How many sigma and pi bonds are there?

Draw the Lewis structure and describe the geometry of the hydrazine molecule, \(\mathrm{N}_{2} \mathrm{H}_{4}\). Would you expect this molecule to be polar?

Consider the polyatomic ion \(\mathrm{IO}_{6}^{5-}\). How many pairs of electrons are around the central iodine atom? What is its hybridization? Describe the geometry of the ion.

Phosphoryl chloride, \(\mathrm{POCl}_{3}\), has the skeleton structure Write (a) a Lewis structure for \(\mathrm{POCl}_{3}\) following the octet rule. Calculate the formal charges in this structure. (b) a Lewis structure in which all the formal charges are zero. (The octet rule need not be followed.)