Name:_____________
(4 points)
Chemistry 114
First Hour Exam
Remember- Show all work for partial credit. Each problem is worth 12 points.
1. Below are four compounds. For each compound: A.) Write a Lewis structure. B.)
Give the geometry around the central atom, and. C.) Give the hybridization of the
central atom.
Note: I am skipping lone pairs on the outside atoms and overall charge on ions
POCl3 (P is central)
XeF4
tetrahedral electron geometry
sp3
ClO3
tetrahedral electron geometry
sp3
Octahedral electron geometry
D2sp3
ClO4--
tetrahedral electron geometry
Sp3
2. A. Explain how you get probonding and antibonding ó bonds when you hybridze s
orbitals together.
This works much better with a diagram. When you hybridize orbitals by adding s
orbitals from two atoms together, the electron density increases between the atoms and
this increased electron density holds the atoms together and creates the pro-bonding
orbital. When you hybridize by subtracting s orbitasl from each other, the electron
density decreases between the atoms so the hybridized electron density does not have
any electron density between the atoms to hold them together, so you create an antibonding orbital.
B. When we use molecular orbital theory to predict the orbitals in Be2, why do we ignore
the 1s orbitals and only hybridize the 2s orbitals?
The 1s orbitals are smaller than the 2s orbitals, so they do not overlap. If they do not
overlap, they cannot hybridize to form bonds.
3. Below are some ionic diatomic molecules that may or may not exist. Show the
ladder of filled and unfilled molecular orbitals then use this diagram to answer the
following questions:
A.) What is the bond order for this compound?.
B.) Which compound is the most stable? The least stable?
C.) Is this compound attracted to, or repelled from, a magnetic field?
CN+
89 89
89
89
OFó*2p
ð*2p
ó2p
ð2p
ó*2s
ó2s
89 89
89 89
89
89
89
BO = (6-2)/2 = 2
Most stable
diamagnetic - repelled
BN2+
ó*2p
ð*2p
ð2p
ó2p
ó*2s
ó2s
8 8
89
89
(8-6)/2=1
Least stable
diamagnetic - repelled
ó*2p
ð*2p
ó2p
ð2p
ó*2s
ó2s
(4-2)/2=1
Least stable
Paramagnetic Attracted
4. Below is the structure of Ibuprophen (Advil).
A. Complete the Lewis structure by showing all lone pairs of electrons.
2 lone pairs on both oxygens
B. How many atoms in this structure are sp, sp2 and sp3 hybridized?
Sp = 0
sp2 7 C’s or 8 total
sp3 6 C’s pr 7 total
C. How many ó and how many ð bonds are there in this structure?
33 ó bonds (1 in every bond)
4 ð bonds (1 in every double bond)
5. Below are the names of 4 organic compounds. Draw the structure corresponding to
these names. The name I gave you may not be correct. If the name is wrong, give the
correct name for this compound.
Cis-2-methyl-3-ethylbutane
3,4-difluorocyclohexane
2,3-Dimethylpentane
1,2-Dibromofluorohexane
2-sec-butylpropanal
methylethylketone
2,3-dimethylpentanal
2-butanone
6. Below is the structure of a hydrocarbon. Predict what will happen to this compound
when it is reacted under the following conditions:
1. Cl2 and ultraviolet light
2. H2 with a Pt catalyst
3. CH3Cl with AlCl3 catalyst
7. Proteins, carbohydrates and nucleic acids are the three major biopolymers found in
your body. For each of these biopolymers give:
The name of the monomer unit...
Amino acid
Simple sugar or polysaccharide
nucleotide
A rough structure of the monomer units...
Phosphate-Ribose - Base
The main functional groups on the monomer...
Amines
Carboxylic Acid
Alcohols
aldehyde or ketone
Phosphate
Alcohols and aldehydes or
Ketones
Amines in rings
8. Auto air conditioning units currently use the hydrofluorocarbon HFC-134a as a
refrigerant. (1,1,1,2-tetrafluoroethane) But it has a global warming potential 1,340 times
greater than CO2, Because of this, it will be banned in Europe in this year.
One alternative that has been proposed is HFO -1234yf (2,3,3,3-tetrafluoropropene)
which has a global warming potential only 4 x worse than CO2. Draw the structure of
these two compounds:
1,1,1,2-tetrafluoroethane
2,3,3,3-tetrafluoropropene