organic chem

Essentials of Organic Chemistry (Bruice)


Chapter 1


Chapter 1Electronic Structure and Covalent Bonding

1)

Atoms with the same number of protons but different numbers of neutrons are called __________.

Answer:

isotopes

Section: 1.1

2)

What isotope of chlorine has the same number of neutrons as Argon-38?

A)

17Cl

B)

35Cl

C)

36Cl

D)

37Cl

E)

38Cl

Answer:

D

Section: 1.1

3)

Which of the following elements does this electronic configuration represent?

1s2 2s2 2p5

A)

F

B)

C

C)

N

D)

Al

E)

O

Answer:

A

Section: 1.2

4)

How many unpaired electrons are present in the isolated carbon atom (atomic number = 6)?

A)

none

B)

one

C)

two

D)

three

E)

four

Answer:

C

Section: 1.2

5)

Which of the following is the electronic configuration of the element Fe?

A)

1s2 2s2 2p6 3s2 3p6 4s2 3d6

B)

1s2 2s2 2p6 3s2 3p8 3d6

C)

1s2 2s2 2p8 3s2 3p6 4s2 3d6

D)

1s2 2s2 2p6 3s2 3p6 4s2 4d6

E)

1s2 2s2 2p6 3s2 3p6 4s2 4p6

Answer:

A

Section: 1.2

6)

Ar, K+, Cl- are isoelectronic elements (elements with the same number of electrons). What orbital does the last electron occupy?

Answer:

3p orbital

Section: 1.2

7)

The atomic number of boron is 5. The correct electronic configuration of boron is:

A)

1s2 2s3

B)

1s2 2p3

C)

1s2 2s2 2p1

D)

2s2 2p3

E)

1s2 2s2 3s1

Answer:

C

Section: 1.2

8)

Which of the following statements correctly describes the third electron shell that surrounds the nucleus of an atom?

A)

The third shell contains only s and p atomic orbitals.

B)

The maximum number of electrons that can occupy the third shell is 18.

C)

The total number of atomic orbitals present in the third shell is 16.

D)

The third shell can contain f orbitals.

E)

none of the above

Answer:

B

Section: 1.2

9)

Which of the following describes a hydride ion?

A)

a negatively charged hydrogen ion containing a pair of electrons

B)

a positively charged hydrogen ion

C)

a hydrogen ion containing a single electron

D)

a negatively charged OH ion

E)

a proton containing an extra electron

Answer:

A

Section: 1.3

10)

Rank the following atoms in increasing electronegativity.

A)

N, Na, Si, O, C

B)

C, N, O, Na, Si

C)

O, N, C, Si, Na

D)

Si, C, N, O, Na

E)

Na, Si, C, N, O

Answer:

E

Section: 1.3

11)

Using the symbol + and -, indicate the direction of the polarity in the indicated bond.

Answer:

Section: 1.3

12)

Covalent bonds may be polar or nonpolar. What property of the atoms forming a given bond determines this?

Answer:

electronegativity

Section: 1.3

13)

The compound methylamine, H3C-NH2, contains a C-N bond. In this bond, which of the following best describes the charge on the nitrogen atom?

A)

+1

B)

slightly positive

C)

uncharged

D)

slightly negative

E)

-1

Answer:

D

Section: 1.3

14)

Which of the compounds below bond predominantly via ionic bonding?

A)

KCl

B)

CF4

C)

NH3

D)

both A and B

E)

both B and C

Answer:

A

Section: 1.3

15)

What type of bonding is most important in CH3CH2CH2CH2CH2CH3?

A)

ionic

B)

hydrogen

C)

covalent

D)

polar

Answer:

C

Section: 1.3

16)

Which of the following contain(s) polar covalent bonds?

A)

NH3

B)

Na2O

C)

H2

D)

KF

E)

both A and C

Answer:

A

Section: 1.3

17)

What is the name given for a species that contains a positively charged carbon atom?

A)

carbanion

B)

carbocation

C)

methyl radical

D)

carbon radical

E)

free radical

Answer:

B

Section: 1.4

18)

Which of the following is the most likely (i.e. most stable) electronic structure for C2H2?

A)

B)

C)

D)

HCCH

E)

Answer:

D

Section: 1.4

19)

Which of the following structures, including formal charges, is correct for diazomethane, H2CN2?

A)

: H2CNN:

B)

C)

D)

E)

Answer:

D

Section: 1.4

20)

What are the formal charges on nitrogen and the starred oxygen atom in the following molecule?

A)

N = -1, O = 0

B)

N = +1, O = -1

C)

N = +1, O = +1

D)

N = -1, O = -1

E)

N= +1, O = 0

Answer:

E

Section: 1.4

21)

Draw the Kekul structure for each of the following:

a.CH3CH2OH b.CH3CHO c.(CH3)3C+

Answer:

Section: 1.4

22)

The formal charge on nitrogen in the compound below is __________.

A)

+2

B)

+1

C)

0

D)

-1

E)

-2

Answer:

B

Section: 1.4

23)

The Kekul structure of pentane is shown below. Draw the condensed structural formula which corresponds to this Lewis structure.

Answer:

CH3(CH2)3CH3

Section: 1.4

24)

Draw condensed structures for the four compounds with formula C3H9N.

Answer:

CH3CH2CH2NH2

CH3CH2NHCH3

(CH3)2CHNH2

(CH3)3N

Section: 1.4

25)

Write a Lewis structure for the molecule given and show all formal charges.

CH2CO

Answer:

Section: 1.4

26)

Expand the condensed structure below to show the covalent bonds and the lone-pair electrons.

(CH3)2CHCH2CHO

Answer:

Section: 1.4

27)

Draw the shape of a 2p orbital.

Answer:

Section: 1.5

28)

How many distinct p orbitals exist in the second electron shell?

A)

0

B)

1

C)

2

D)

3

E)

4

Answer:

D

Section: 1.5

29)

Both sigma () and pi () bonds can be formed by overlapping p orbitals. Describe the difference.

Answer:

Sigma bonds are formed from the overlap of atomic orbitals along a circular axis of symmetrical nature, i.e., head-on overlap. All single bonds are sigma bonds.

Pi bonds are formed from the overlap of atomic orbitals along a non-symmetrical (parallel) axis, i.e., side-to-side overlap. Double and triple bonds are pi bonds.

Section: 1.6 and 1.8

30)

Choose the correct hybridization for the atom indicated in the molecule below.

CH3CH2CH2CH3

A)

sp

B)

sp2

C)

sp3

D)

none of the above

Answer:

C

Section: 1.7

31)

What orbitals are used to form the covalent bonds in butane (CH3CH2CH2CH3)?

Answer:

The carbon-carbon bonds are formed by the overlap of two carbon sp3 hybrid atomic orbitals. The carbon-hydrogen bonds are formed by the overlap of a carbon sp3 hybrid atomic orbital and a hydrogen s orbital.

Section: 1.7

32)

Which of the following is a nonpolar molecule?

A)

HCl

B)

CH3Cl

C)

H2

D)

CO

E)

NH3

Answer:

C


33)

Which of the following is a correct formula for a compound?

A)

CH3CH2(CH3)2CH2CH3

B)

CH2CH2(CH3)CH2CH3

C)

CH3CH(CH3)CH2CH3

D)

CH3CH2(CH3)2

E)

C

Answer:

C

Section: 1.7

34)

How many electrons are involved in a carbon-carbon double bond?

A)

1

B)

2

C)

3

D)

4

E)

5

Answer:

D

Section: 1.8

35)

Which of the following describes a triple bond?

A)

two sigma bonds and two pi bonds

B)

three pi bonds

C)

one sigma bond and one pi bond

D)

two sigma bonds and one pi bond

E)

one sigma bond and two pi bonds

Answer:

E

Section: 1.9

36)

Which carbon(s) in the following molecule is (are) sp hybridized?

A)

carbon 1

B)

carbon 2

C)

carbon 1, 3

D)

carbon 4

E)

carbon 4, 5

Answer:

E

Section: 1.9

37)

Which of the following is an sp2 hybridized carbon?

A)

B)

CH3

C)

D)

A and B

E)

A, B and C

Answer:

A

Section: 1.10

38)

What is the predicted shape, bond angle, and hybridization for +CH3?

A)

trigonal planar, 120, sp2

B)

trigonal planar, 120, sp3

C)

trigonal planar, 109.5, sp2

D)

trigonal pyramidal, 120, sp2

E)

trigonal pyramidal, 109.5, sp2

Answer:

A


39)

What orbitals overlap to create the H-C bond in CH3+?

A)

sp3-sp3

B)

sp2-sp3

C)

s-p

D)

s-sp2

E)

s-sp3

Answer:

D

Section: 1.10

40)

The lone-pair electrons of the methyl anion occupy a __________ orbital.

A)

s

B)

p

C)

sp

D)

sp2

E)

sp3

Answer:

E

Section: 1.10

41)

Explain why the water molecule has a bent shape and a bond angle less than 109.5.

Answer:

The electron replusion between the two lone pairs of electrons on the oxygen of water causes the O-H bonds to squeeze close together.

Section: 1.11

42)

Which of the following is closest to the C-O-C bond angle in CH3-O-CH3?

A)

180

B)

120

C)

109.5

D)

90

E)

160

Answer:

C

Section: 1.11

43)

Triethylamine [(CH3CH2)3N] is a molecule in which the nitrogen atom is __________ hybridized and the CNC bond angle is __________.

A)

sp2; >109.5

B)

sp2; 109.5

D)

sp3;

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