Draw all reasonable resonance structures for each species. a. O3 c. N3 e. + g. O + b

While the most common isotope of nitrogen has a mass number of 14 (nitrogen-14), a radioactive isotope of nitrogen has a mass number of 13 (nitrogen-13). Nitrogen-13 is used in PET (positron emission tomography) scans by physicians to monitor brain activity and diagnose dementia. For each isotope, give the following information: (a) the number of protons; (b) the number of neutrons; (c) the number of electrons in the neutral atom; and (d) the group number

Consider the three atoms: [1] 3 1 1 5P; [2] 19 9F; and [3] 2 1H. For each atom give the following information: (a) the atomic number; (b) the total number of electrons in the neutral atom; (c) the number of valence electrons; and (d) the group number

Label each bond in the following compounds as ionic or covalent. a. F2 b. LiBr c. CH3CH3 d. NaNH2

An element like fl uorine forms either ionic or covalent bonds, depending on the identity of the element to which it bonds. What type of bonding is observed in each compound: (a) NaF, a toothpaste ingredient added to strengthen tooth enamel; (b) CFCl3, a chlorofl uorocarbon once widely used as an aerosol propellant? Explain why a difference is observed.

How many covalent bonds are predicted for each atom? a. O b. Al c. Br d. Si

Draw a valid Lewis structure for each species: a. CH3CH3 b. CH5N c. CH3 d. CH3Cl

Draw an acceptable Lewis structure for each compound, assuming the atoms are connected as arranged. Hydrogen cyanide (HCN) is a poison, formaldehyde (H2CO) is a preservative, and glycolic acid (HOCH2CO2H) is used to make dissolving sutures. H O a. HCN H C N b. H2CO H C O c. HOCH2CO2H H O C C O H H H

Calculate the formal charge on each second-row atom: a. H N H H H + b. CH3 N C c. O O

Draw a Lewis structure for each ion: a. CH3O b. HC2 c. (CH3NH3) + d. (CH3NH)

Classify each pair of compounds as isomers or resonance structures. a. NO CO C and N + b. HO C O O and HO C O O

Considering structures AD, classify each pair of compounds as isomers, resonance structures, or neither: (a) A and B; (b) A and C; (c) A and D; (d) B and D. + CH3 C OH B CH3 OHC O H H C O CH2OH C D O CH3 C OH A O

Follow the curved arrows to draw a second resonance structure for each species. a. H H C O b. CH3 C H C H CH2

Use curved arrow notation to show how the fi rst resonance structure can be converted to the second. a. CH2 C C CH3 CH2 C C CH3 H H H H + + b. O O O O O C C O

Draw a second resonance structure for each species. a. C C CH3 HH CH3 H C + b. CH3 C CH3 Cl + c. H H C H C C

Label the resonance structures in each pair as major, minor, or equal contributors to the hybrid. Then draw the hybrid. a. CH3 C H N H CH3 CH3 C H N H CH3 + + b. CH2 C CH2 H CH2 C CH2 H

Draw a second resonance structure for nitrous acid. Label each resonance structure as a major, minor, or equal contributor to the hybrid. Then draw the resonance hybrid. H O O N nitrous acid

Draw two different three-dimensional representations for CH2Cl2 (dichloromethane) using wedges and dashes.

Determine the geometry around all second-row elements in each compound. a. CH3 C O CH3 b. CH3 O CH3 c. NH2 d. CH3 C N

Using the principles of VSEPR theory, you can predict the geometry around any atom in any molecule, no matter how complex. Enanthotoxin is a poisonous compound isolated from a common variety of hemlock grown in England. Predict the geometry around the indicated atoms in enanthotoxin. C C C C C C H H C C H H CC H H H H C H H C O H C enanthotoxin H H HO H H H C H H CH3

Convert each condensed formula to a Lewis structure. a. CH3(CH2)4CH(CH3)2 c. (CH3)3CCH(OH)CH2CH3 b. (CH3)2CHCH(CH2CH3)2 d. (CH3)2CHCHO

Simplify each condensed structure by using parentheses around similar groups. a. CH3CH2CH2CH2CH2Cl c. C CH2OH H HOCH2 CH2CH2CH2 C CH2 CH3 CH3 C CH3 CH3 CH3 b. CH3CH2CH2 C CH2CH3 H CH2CH3

During periods of strenuous exercise, the buildup of lactic acid [CH3CH(OH)CO2H] causes the aching feeling in sore muscles. Convert this condensed structure to a Lewis structure of lactic acid.

How many hydrogen atoms are present around each indicated carbon atom in the following molecules? Both compounds are active ingredients in some common sunscreens. O O O avobenzone O O O octinoxate (2-ethylhexyl 4-methoxycinnamate) a. b.

Convert each skeletal structure to a Lewis structure. a. b. O c. Cl d. N N H

Draw in all hydrogens and lone pairs on the charged carbons in each ion. a. + b. c. + d. O

Draw a skeletal structure for the molecules in parts (a) and (b), and a condensed structure for the molecules in parts (c) and (d). a. \(\left(\mathrm{CH}_{3}\right)_{2} \mathrm{C}=\mathrm{CH}\left(\mathrm{CH}_{2}\right)_{4} \mathrm{CH}_{3}\) b. c. d.

What orbitals are used to form each of the C C and C H bonds in CH3CH2CH3 (propane)? How many bonds are present in this molecule?

Determine the hybridization around the indicated atoms in the following molecules: a. CH3 C CH b. N CH3 c. CH2 C CH2

Classify each bond in the following molecules as or : a. CH3 C H O b. CH3 C N c. H C OCH3 O

Rank the indicated bonds in each compound in order of (a) increasing bond strength and (b) increasing bond length. a. bond 3 C C bond 1 bond 2 b. bond 1 bond 2 N H N CH3 C N bond 3

Which of the indicated bonds in each pair of compounds is shorter? a. CH3 C C H or H C CH2 CH3 c. CH2 N CH3 H H or N H b. H H H H C O Hor C OH

Rank the following atoms in order of increasing electronegativity. Label the most electronegative and most electropositive atom in each group. a. Se, O, S b. P, Na, Cl c. Cl, S, F d. O, P, N

Show the direction of the dipole in each bond. Label the atoms with + and . a. H F b. B C c. C Li d. C Cl

Indicate which of the following molecules is polar because it possesses a net dipole. Show the direction of the net dipole if one exists. a. CH3Br b. CH2Br2 c. CF4 d. H Cl Cl H C C e. H Cl H Cl C C

Provide the following information about L-dopa. In all cases, label different sites than those identifi ed in the structure shown. a. Label two polar and two nonpolar bonds. b. Label all sp3 hybridized C atoms. c. Label all H atoms that bear a partial positive charge (+ ). d. Draw another resonance structure.

Two radioactive isotopes of iodine used for the diagnosis and treatment of thyroid disease have mass numbers of 123 and 131. For each isotope, give the following information: (a) the number of protons; (b) the number of neutrons; (c) the number of electrons in the neutral atom; (d) the group number.

Assign formal charges to each carbon atom in the given species. All lone pairs have been drawn in. a. CH2 CH b. H C H c. H H H C d. H H C H H H C

Assign formal charges to each N and O atom in the given molecules. All lone pairs have been drawn in. a. CH3 N CH3 c. CH3 N N e. CH3 O b. N N N d. CH3 C CH3 OH f. CH3 N O

Draw one valid Lewis structure for each compound. Assume the atoms are arranged as drawn. a. CH2N2 H C H N N c. CH3CNO H C H H CN O e. HCO3 HOC O O b. CH3NO2 H C H H N O O d. HCO2 H C O O f. CH2CN H C H C N

Draw a valid Lewis structure for each compound. a. N2 b. (CH3OH2) + c. (CH3CH2) d. HNNH e. H6BN

Draw an acceptable Lewis structure from each condensed structure, such that all atoms have zero formal charge. a. diethyl ether, (CH3CH2)2O, the fi rst general anesthetic used in medical procedures b. acrylonitrile, CH2CHCN, starting material used to manufacture synthetic Orlon fi bers c. dihydroxyacetone, (HOCH2)2CO, an ingredient in sunless tanning products d. acetic anhydride, (CH3CO)2O, a reagent used to synthesize aspirin

Draw all possible isomers for each molecular formula. a. C3H7Cl (two isomers) b. C2H4O (three isomers) c. C3H9N (four isomers)

Draw Lewis structures for the nine isomers having molecular formula C3H6O, with all atoms having a zero formal charge.

With reference to compound A drawn below, label each compound as an isomer, a resonance structure, or neither. A O a. O b. O c. O + d. O CH2

With reference to species B, label each species as an isomer, a resonance structure, or neither. + B a. + b. + c. + d. +

Add curved arrows to show how the fi rst resonance structure can be converted into the second. a. CH3 C N H H CH3 CH3 C H N H CH3 + + c. CH2 CH2 b. O NH2 O NH2 + H C H C

Follow the curved arrows to draw a second resonance structure for each species. a. 3 NNCH + b. CH3 C CH O CH2 + c. CH3 + d. NH2 +

Draw a second resonance structure for each ion. a. CH3 C O O b. CH2 NH2 + c. O d. H OH + H C

For each ion in Problem 1.53 draw the resonance hybrid.

Draw all reasonable resonance structures for each species. a. O3 c. N3 e. + g. O + b. NO3 (a central N atom) d. CH3 C O CH C CH3 O f. CH2 CH CH CH CH2

Draw four additional resonance structures for the following cation. Then draw the resonance hybrid. CH2

Rank the resonance structures in each group in order of increasing contribution to the resonance hybrid. Label the resonance structure that contributes the most as 3 and the resonance structure that contributes the least as 1. Label the intermediate contributor as 2. a. CH3 C O CH3 O CH3 C O CH3 O CH3 C O CH3 O + + b. CH3 C N NH2 CH3 CH3 C N NH2 CH3 CH3 C N NH2 CH3

Consider the compounds and ions with curved arrows drawn below. When the curved arrows give a second valid resonance structure, draw the resonance structure. When the curved arrows generate an invalid Lewis structure, explain why the structure is unacceptable. a. b. c. CH3CH2 C N d. O

Predict all bond angles in each compound. a. CH3Cl b. NH2OH c. CH2 NCH3 d. HC CCH2OH e. C

Draw the structure of halothane, CF3CHClBr, in three dimensions, using solid lines, wedges, and dashes to illustrate the position of atoms. Halothane is a safe and widely used general anesthetic.

How many hydrogens are present around each carbon atom in the following molecules? a. capsaicin (spicy component of hot peppers) N O HO O H b. OH N fexofenadine (nonsedating antihistamine) OH COOH

Draw in all the carbon and hydrogen atoms in each molecule. a. OH menthol (isolated from peppermint oil) b. myrcene (isolated from bayberry) c. N H H N OH OH ethambutol (drug used to treat tuberculosis) d. OH HO estradiol (a female sex hormone)

Convert each molecule into a skeletal structure. a. \((CH_3)_2CHCH_2CH_2CH(CH_3)_2\) b. \(CH_3CH(Cl)CH(OH)CH_3\) c. \((CH_3)_3C(CH_2)_5CH_3\) d. e. f. \(CH_3(CH_2)_2C(CH_3)_2CH(CH_3)CH(CH_3)CH(Br)CH_3\)

Convert the following condensed formulas into Lewis structures. a. CH3CH2COOH c. CH3COCH2Br e. (CH3)3CCHO g. CH3COCH2CO2H b. CH3CONHCH3 d. (CH3)3COH f. CH3COCl h. HO2CCH(OH)CO2H

Draw in all the hydrogen atoms and nonbonded electron pairs in each ion. a. b. O c. + d. +

Draw in all H atoms and lone pairs in each ion. a. NCH3 b. NH + c. O O d. O N

Each of the following condensed or skeletal structures is an incorrect representation of a molecule or ion. Explain what is wrong in each structure. a. CH3CH CH CHCH3 c. OH d. e. CH2CH3 CH2CH3 b. (CH3)3CHCH2CH2CH3

Predict the hybridization and geometry around each indicated atom. a. CH3CH2 c. (CH3)3O+ e. CH3 C C H g. CH3CH C CH2 b. d. CH2Cl f. CH2 NOCH3

Citric acid and zingerone are two naturally occurring compounds. What orbitals are used to form each indicated bond? a. HO O O CO2H H citric acid (responsible for the tartness of citrus fruits) CO2H b. zingerone (responsible for the pungent taste of ginger) O CH3 HO H

Ketene, CH2 C O, is an unusual organic molecule that has a single carbon atom doubly bonded to two different atoms. Determine the hybridization of both C atoms and the O in ketene. Then, draw a diagram showing what orbitals are used to form each bond (similar to Figures 1.12 and 1.13).

Consider the unstable cation and anion drawn below. CH2 CH CH2 CH + a. What is the hybridization of each carbon atom in these ions? b. What orbitals are used to form both bonds in each carboncarbon double bond?

Rank the following bonds in order of increasing bond length. a. C C H C C H H H C H H CH3 b. C CC H C H H

Indicate the longer labeled bond in each compound. a. HO NH2 b. Br Cl c. N NH2

Answer the following questions about compound A a. Label the shortest C C single bond. b. Label the longest C C single bond. c. Considering all the bonds, label the shortest C C bond. d. Label the weakest C C bond. e. Label the strongest C H bond. f. Explain why bond (1) and bond (2) are different in length, even though they are both C C single bonds.

A bond formed from two sp2 hybridized C atoms is stronger than a bond formed from two sp3 hybridized C atoms. Explain.

Two useful organic compounds that contain Cl atoms are drawn below. Vinyl chloride is the starting material used to prepare poly(vinyl chloride), a plastic used in insulation, pipes, and bottles. Chloroethane (ethyl chloride) is a local anesthetic. Why is the C Cl bond of vinyl chloride stronger than the C Cl bond in chloroethane? CH2 CHCl CH3CH2Cl chloroethane (ethyl chloride)

Answer each question with a brief explanation and an example to illustrate your answer. a. Can a compound be nonpolar if it contains one polar bond? b. Can a compound be nonpolar if it contains two or more polar bonds? c. Can a compound be polar if it contains no polar bonds?

Label the polar bonds in each molecule. Indicate the direction of the net dipole (if there is one). a. CHBr3 d. C CH3 CH3 O e. Br Br f. Cl Cl b. CH3CH2OCH2CH3 c. CBr4

Answer the following questions about acetonitrile (CH3C N:). a. Determine the hybridization of both C atoms and the N atom. c. In what type of orbital does the lone pair on N reside? b. Label all bonds as or . d. Label all bonds as polar or nonpolar.

Benzene is the simplest member of a whole class of compounds called aromatic hydrocarbons. benzene a. How is each carbon atom hybridized? b. What is the geometry around each carbon atom? What is the overall geometry of the benzene ring? c. Draw a diagram showing the orbitals used to join the carbon atoms of the ring. d. Follow the indicated curved arrow notation to draw a second resonance structure. e. Benzene and other aromatic hydrocarbons are shown in Chapter 17 to be very stable. Offer an explanation.

The principles of this chapter can be applied to organic molecules of any size. Answer the following questions about amoxicillin, an antibiotic from the penicillin family. C H C O N H N S HH HO H H O H H H C HO O amoxicillin NH2 CH3 CH3 a. Predict the hybridization and geometry around each indicated atom. d. How many bonds does amoxicillin have? b. Label fi ve polar bonds using the symbols + and . Label them. c. Draw a skeletal structure. e. Find a C H bond containing a carbon atom having a hybrid orbital with 33% s-character

a. What is the hybridization of each N atom in nicotine? b. What is the geometry around each N atom? c. In what type of orbital does the lone pair on each N atom reside? d. Draw a constitutional isomer of nicotine. e. Draw a resonance structure of nicotine.N N nicotine CH3

Stalevo is the trade name for a medication used for Parkinsons disease, which contains both L-dopa and entacapone. entacapone HO HO CN NO2 CON(CH2CH3)2 a. Draw a Lewis structure for entacapone. b. Which CC bond in entacapone is the longest? c. Which CC single bond is the shortest? d. Which CN bond is the longest? e. Which CN bond is the shortest? f. Use curved arrows to draw a resonance structure that is an equal contributor to the resonance hybrid. g. Use curved arrows to draw a resonance structure that is a minor contributor to the resonance hybrid

CH3 + and CH3 are two highly reactive carbon species. a. What is the predicted hybridization and geometry around each carbon atom? b. Two electrostatic potential plots are drawn for these species. Which ion corresponds to which diagram and why? A B

When two carbons having different hybridization are bonded together, the C C bond contains a slight dipole. In a Csp2 Csp3 bond, what is the direction of the dipole? Which carbon is considered more electronegative?

Draw all possible isomers having molecular formula C4H8 that contain one bond.

The curved arrow notation introduced in Section 1.5 is a powerful method used by organic chemists to show the movement of electrons not only in resonance structures, but also in chemical reactions. Since each curved arrow shows the movement of two electrons, following the curved arrows illustrates what bonds are broken and formed in a reaction. Consider the following threestep process. (a) Add curved arrows in Step [1] to show the movement of electrons. (b) Use the curved arrows drawn in Step [2] to identify the structure of X. X is converted in Step [3] to phenol and HCl. H H O H Cl Cl HO H H [1] + + + H Cl + HO H H + OH phenol Cl [2] [3] X