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.
Electron Affinity The reaction :Y(g) + e-6Y-(g)
An excited state: When an electron in an atom gains energy to move into a higher
energy orbital.
Covalent bond A bond formed when two atoms share electrons to bind the atoms
together into a molecule.
Isoelectronic Atoms or ions with the same electron configuration.
Photon A quantum of electromagnetic energy
2. A photon has an energy of 73.6x10-20 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=2, R=1, mR= +1, ms = -1/2
____1______
n=0, R=1, mR= +1, ms = +1/2
____0______
n=4, R=2
____10______
n=3, R=p, mR= +1,
____2______
n=2,
_____2_____
mR= +1,
n=3,
ms=+½
_____9_____
4A. Write the correct molecular formulas for the following compounds:
Silver iodide
AgI
Potassium selinide
K2 S
Magnesium(IV) nitride
Magnesium is always a +2 and should not have a Roman numeral! I meant to say
Manganese(IV) nitride
If you did Magnesium(IV) nitride the correct answer is Mg3N4
If you corrected me and did Magnesium nitride the answer is Mg3N2
4B Write the correct names for the following compounds:
NaI
Sodium Iodide
CrO3
Chromium(VI) oxide
N 2O5
Dinitrogen pentaoxide
3
5. Given the following information:
The 1st ionization energy of K is 6.96 aJ
The Electron affinity of F is -5.50 aJ
The radius of K+ is 133 pM and the radius of F- is 136 pm
Calculate the energy involved in the reaction:
K(g) + F(g) 6KF(g)
ETotal = E ionization + E electron affinity + E coulomb
E coulomb = 231 aJApm (Q1Q2)/d
d= 133 pm + 136 pm = 269 pm
E coulomb = 231 aJApm (1×-1)/269 pm
= -.86 aJ
ETotal = 6.96 - 5.50 -.86 = +.60 aJ
6. Draw Lewis Structures for the following compounds
CCl3H (C is central)
XeF4
BH3
NO2-
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:
Co,
Ir, La, Sc
Largest (Most negative) electron affinity:
C, O, S, Si
Is the most electronegative:
Cl, I,
S,
Te
Has the largest radius:
Ar,
Be2+, Cl-, K+,
N3-, Ne