Fall 08: Exam 1. Ch 1-4
100points
Name
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1-15 are True / False. (15pts)
1)
The Periodic Table has the elements arranged in increasing atomic
number
2)
A σ bond is a covalent bond
3)
Carbon has a larger atomic radius than Nitrogen
4)
Fluorine is more electronegative than Carbon
5)
Carbon has a larger atomic radius than Silicon
6)
The electron configuration of Be is 1s2 2s 22p1
7)
Carbon has 6 electrons but only 4 valence electrons
8)
Cyclobutane has more ring strain than cyclopentane
9)
An sp hybridized atom has two unhybridized p orbitals
10)
Hexane and cyclohexane are isomers
11)
Cyclopentane has zero ring strain
12)
Kinetics provide information about the position of equilibrium
13)
The lowest energy conformation of butane is anti
14)
Pentane has zero ring strain
15)
sp3 hybrid orbitals are of higher energy than sp hybrid orbitals
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16) Draw Lewis structures (lines for bonds and dots for all lone pairs) for the
following molecules: (6pts)
(a)
(b)
B(OH)3
NH
O
17) (16pts): For the below molecule, calculate the number of…
N
a) carbon atoms
N
b) hydrogen atoms
c) nitrogen atoms
d) rings
e) sp2 hybridized carbons
f) sp2 hybridized atoms
g) sp3 hybridized atoms
h) lone pairs (non bonding pairs) of electrons
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18) (8pts) (i) What is meant by the term Kinetics?
(ii) What is meant by Structural Isomer?
(iii) What two components contribute to ring strain?
(iv) Provide an everyday example of an increase in Entropy.
19) (12pts): For the below energy level diagram…
a) is this reaction exothermic or endothermic ?
b) Will the Equilibrium constant (K) be greater or less than 1.00 ?
c) how many transition states are there ?
d) how many steps is this multistep reaction ?
e) which step is the rate determining step ?
f) which is the fastest step ?
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20) Name the following compounds in IUPAC form. (15pts)
(a)
(b)
CH3CH2
CH2CH3
CH3
(c)
CH3CH2
H
CH3
H
H
(d)
(e)
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21) Circle the more stable member of each pair (8pts)
(a)
OH
OH
F
(b)
Cl
Cl
F
Br
Br
H
H
CH3
(c)
Br
C(CH3)3
(d)
CH3
Br
CH2CH3
H
H
CH2CH3
H
C(CH3)3
H
22) Draw in the axial C-H bonds on this chair cyclohexane (3pts)
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23) In the lowest energy conformation of trans-1,4-dimethylcyclohexane,
how many axial positions are occupied by Hydrogen atoms ? (5pts)
24) In the lowest energy conformation of cis-1,4-dimethylcyclohexane, how
many axial positions are occupied by Hydrogen atoms ? (5pts)
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25) Explain why the methyl radical ( •CH3 ) has H-C-H bond angles of 120°.
(7pts)
***Bonus question for 2 points***
What is the difference between bond angle and dihedral angle ?
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