NAME:
CHE 121 SUMMER QUARTER 2008
QUIZ 4
This quiz is worth 15 marks the value for each question is as indicated. You have 25
minutes to complete the quiz. Do not open this paper until instructed. You may use
dictionaries, calculators and any data sheets provided by the instructor. Use only the
scratch paper provided by the instructor. Please write your name in pen clearly at the
top of this page. No other materials are to be used. Mobile phones are to be turned off
and placed out of sight. Everything other than this test paper and the materials
described above should be placed inside your bag. Students who cheat will receive
zero for this quiz. Students who cheat more than once will be dropped from the
course. Allowing someone to copy your work is considered cheating. Once you have
completed the quiz remain quietly seated until the instructor collects your paper.
Please be respectful to other students who may still be working. Once instructed to
stop writing close your quiz and cease writing immediately. Attempting this quiz is an
acknowledgement you have read, understood and agreed to abide by the rules
outlined above.
In order to obtain full credit you must show all working and give answers to the
correct number of significant figures and give the appropriate units.
Constants:
NA = 6.022 x 1023 particles per mole
1. Write the electronic configurations for the first four noble gases and for
each identify the valence shell electrons.
(1 mark)
Helium 1s2
Neon 1s22s22p6
Argon 1s22s22p63s23p6
Krypton 1s22s22p63s23p64s23d104p6
2. Draw Lewis structures for atoms of the following:
a. Element 4
b. Cesium (Cs)
c. Aluminum (Al)
d. Selenium (Se)
(1 mark)
3. Show how the following atoms achieve a noble gas configuration and
become ions by losing or gaining electrons.
a. Na
b. Cl
c. Mg
d. O
(2 marks)
a. Sodium loses 1 electron to become like neon. [Ne]3s1 → [Ne]
b. Chlorine gains one electron to become like argon [Ne]3s23p5 → [Ar]
c. Magnesium loses two electrons to become like neon [Ne]3s2 → [Ne]
d. Oxygen gains two electrons to become like neon [He]2s22p4 → [Ne]
4. Identify the element in period 2 that would form each of the following
ions. E is used as a general symbol for an element.
a. Eb. E2+
c. E3d. E+
(2 marks)
a. F
b. Be
c. N
d. Li
5. Name the following binary ionic compounds:
a. KCl
b. SrO
c. Ca3N2
(1 mark)
a. potassium chloride
b. strontium oxide
c. calcium nitride
6. Name and give the formual for the binary ionic compound formed
between the simple ions Cr2+ and S2-,
Chromium(II) sulfide
(1 mark)
7. Determine the following:
a. The formula of magnesium chloride
b. The formula weight of magnesium chloride
c. The number of chloride ions in 1.0 mol of magnesium chloride
(2 marks)
a. MgCl2
b. 95.21 gmol-1
c. 2.0 x 6.022 x 1023 = 1.2 x 1024 Cl- ions
8. Represent the following using Lewis structures:
a. Cl + Cl → Cl2
b. H + H → H2
(1 mark)
9. Draw Lewis sturctures for the following molecules:
a. NH3
b. SO3
c. H2O
(2 marks)
10. Using VSEPR theory determine the shape of the molecules given in
question 9, you must show all working to obtain credit and give the
correct name.
a. trigonal pyrimidal
b. trigonal planar
c. bent
(2 marks)
11. Name the following binary covalent compounds:
a. CO2
b. CO
c. NO2
d. N2O5
e. CS2
a. carbon dioxide
b. carbon monoxide
c. nitrogen dioxide
d. dinitrogen pentoxide
e. carbon disulfide
(1 mark)