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Name:_____________
(4 points)
Chemistry 114
First Hour Exam
Remember- Show all work for partial credit. Each problem is worth 14 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.
SO42-
Elec geo: Tetrahedral
Mol geo: Tetrahedral
Hybridization: sp3
BeH2
Elec geo: Linear
Mol geo: Linear
Hybridization: sp
XeF4
Elec geo: octahedral
Mol geo: Square planar
Hybridization: d2sp3
N2 O
Elec geo: Linear
Mol geo: Linear
Hybridization: sp
2 A.
What orbitals can form ó bonds?
s and p atomic orbitals can both form sigma bonds
What orbitals can form ð bonds?
Only p atomic orbitals can form pi bonds
What is a ð* orbital?
This is a pi antibonding orbital with an electron density not along the line connecting the
atoms and not between the atoms
B. Atoms in a single bond can rotate without breaking the bond. Atoms in double
bonds cannot. Explain.
Because single (ó) bonds are along the line connecting the atoms, as you rotate
the atom, nothing changes, so the bond remains intact. The ð part of a double bond is
not along the line connecting the atoms, so if an atom rotates, the p orbitals that make
up the pi bond also rotate. Since a bond can only form where orbital overlap, if the
atoms rotate enough to move the p orbitals on the two atoms out of alignment, the bond
would break.
C. Why can O only form sp, sp2 and sp3 hybridized bonds, while S can form sp, sp2 and
sp3 hybridized bonds?
O is on the second row of the periodic table, so it has a principle quantum number
of 2, and can only have s and p orbitals so it can only make sp, sp2 and sp3 hybridized
orbitals. S is on the third row of the periodic table, so it has a principle quantum number
of 3, and has s, p, and d orbital available, so it can form sp, sp2 and sp3 hybridized
orbitals.
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?
CN6e__ó*2p
__ __ð 2p
89 ó2p
89 89 ð2p
89 ó*2s
89 ó2s
Be2
4 e-
89 ó*2s
89 ó2s
BO=(2-2)/2=0
Least stable
paired electrons
diamagnetic
slightly repelled
BO =(8-2)/2=3
Most stable
paired electrons
diamagnetic
slightly repelled
OF
13e__ó*2p
89 8_ ð*2p
*
89 89 ð2p
89 ó2p
89 ó* 2s
89 ó 2s
BO=(8-5)/2=1.5
One unpaired electron
Paramagnetic
Attracted
4. Below is the structure of Naproxen (Aleve).
A. Complete the Lewis structure by showing all lone pairs of electrons.
Two lone pairs on each oxygen
B. How many atoms in this structure are sp, sp2 and sp3 hybridized?
sp:0
sp2: 12
sp3: 5
C. How many ó and how many ð bonds are there in this structure?
ó:31 ð: 6
5. Below are four organic molecules. Give the correct names for these molecules.
_____4-methyl-2-heptene___________
_____2-isopropylcyclopentanol_____
_____1,3-dibromobenzene_______
______3-amino-4-bromopentanal_____
6. Chemical Alchemy
How could I change the following starting compounds to products. For each
reaction give the other necessary reactant, any catalyst, and any other product
CH3CH3
+ ____Cl2_____
6
CH3CH2Cl + __HCl_______
____hí_____
(Catalyst)
CH3CH3
+ ____________
6
CH2=CH2 + ___H2______
___Cr2O3____
(Catalyst)
C6H6
(Benzene)
+ ___Cl2______
6
__HCl____ +
___AlCl3___
(Catalyst)
7. Below are examples of three biopolymers. For each biopolymer
A. Give the common name of the polymer
B. Give the common name of the monomer
C. Give the main function of the polymer in the body
D. Circle and identify three different functional groups on each polymer
A. Amino acid
B. Protein
C. Catalysis and structure
D. Carboxylic acid, alcohol, amide
A. Simple sugar
B. Carbohydrate
C. Energy storage
D. Carboxylic Acid, Alcohol, Amine, Ether
A. Nucleotide
B. Nucleic Acid
C. Information Storage
D. Because of complicated
structure, individual functional groups are
hard to locate on this structure.