Chemistry 112
First Hour Exam
Name:____________
(4 points)
Please show all work for partial credit
All problems are worth 12 points
Please read and sign the following statement:
I understand that this test is being given over the course of several days. As a
result, I will not discuss the problems on this test with anyone until after Noon on Friday,
October 19th.
Signed: ___________________ Date: ______________
1. Define (or give an equation for) the following terms:
Anion - A negatively charged ion.
Ionic Bond A electrostatic bond formed between an anion and a cation.
Coulomb’s Law
Isoelectronic Atoms or ions with the same electron configuration.
Dipole moment - A molecule with a partial positive charge at one point in the
structure and a partial negative charge at another point in the structure.
Free Radical An atom or molecule with an odd number of electrons.
2. A photon has an energy of 7.5x10-17 J.
What is the frequency of light associated with that photon?
What is the wavelength of light associated with that photon?
(You could also use the frequency from the first part in the equation c=ëí.)
What is the mass of that photon?
2
3. How many electrons can have the following quantum number(s)? (Note: You can
answer zero if the quantum state is not allowed!)
n=3, R=1, mR= -1, ms = +1/2
_____1_____
n=3,
ms=+1/2
____9______
n=1, R=0, mR= +1, ms = -1/2
_____0_____
n=4, R=2
_____10_____
n=4, R=d, mR= +1, ms = -1/2
____1______
n=2,
____2______
mR= +1,
4A. Write the correct molecular formulas for the following compounds:
Zinc fluoride
ZnF2
Sodium sulfide
Na2S
Chromium (VI) oxide
CrO3
4B Write the correct names for the following compounds:
CaS
Calcium sulfide
MnO2
Manganese(IV) oxide
SF6
Sulfur hexafluoride
3
5. Given the following information:
The 1st ionization energy of K is 6.96 aJ
The Electron affinity of Cl is -5.84 aJ
The radius of K+ is 133 pM and the radius of Cl- is 181 pm
Calculate the energy involved in the reaction:
K(g) + Cl(g) 6KCl(g)
ETotal = E ionization + E electron affinity + E coulomb
E coulomb = 231 aJApm (Q1Q2)/d
D= 133 pm + 181 pm = 314 pm
E coulomb = 231 aJApm (1×-1)/314 pm
= -.74 aJ
ETotal = 6.96 - 5.84 -.74 = +.38 aJ
6. Draw Lewis Structures for the following compounds
CCl2H2 (C is central)
PF5
AlF3
CH2O (C is central)
4
7. A covalent compound that contains 1 atom each of hydrogen, carbon and nitrogen can
have more than one Lewis structure. Write all the plausible Lewis structures for this
molecule and use formal charge to determine the ‘best’ structure
Formal charge
Valence e
Assigned e
FC.
1
1
0
5 4
4
5
+1 -1
1 4
1 4
0 0
5
5
0
BEST
8. Periodic Properties
Circle the element or ion has the:
Lowest first ionization energy:
Ba, Ca, Ta, V
Smallest (Leat negative) electron affinity:
As, Br,
Cl,
P
Is the most electronegative:
C, O, S,
Si
Has the smallest radius:
Br-, Ca2+,
Kr,
Li+, Ne, O2-