chem exam

Topics: VSEPR theory, Lewis structure, Molecule Pages: 3 (664 words) Published: November 27, 2013
WHAT:Printed questionnaire with the answers written in a big yellow booklet. One page per
number. Paginate each page accordingly. Use different inks to distinguish the bonds of
electrons for numbers involving molecular structure.
WHO: All students with Student Number ending in ODD number will answer Set A while students
with Student Number ending in EVEN number will answer Set B. Indicate your Student Number and the Set you are answering in front of the yellow booklet. WHEN: Deadline of submission is at 9 AM on Monday, February 20, 2012. Late take home quiz will be

considered NULL and VOID.
WHERE: Under NIEVA pigeon hole at the ChE-Chm Consultation Room, NW 3rd Floor.

Answer the following questions. Follow the specific directions for each item. If Set A or B is indicated, kindly answer only the specified Set assigned to you. Deductions will be given to those not following instructions. Use your resourcefulness in getting necessary data to solve the problem. Do not merely rely on the powerpoint lectures. 1. How many possible resonance structures exist for the formate ion, HCO2-? Draw the possible structures. (5 pts)

2. Set A:How many total valence electrons are present in nitrogen dioxide? Show the computations used in the
prediction as well as the Lewis structure of the compound. (5 pts) Set B:How many electrons are available for bonding in phosphate ion, PO43-? Show the computations used in the
prediction as well as the Lewis structure of the compound. (5 pts)

3. Which of the following elements is most likely to form a molecule or ion that exceeds the octet rule? (5 pts)
A. Na B. S C. B D. F E. C

4. For the singly bonded Lewis dot structure for BF3. Which of the following statements best describes this structure? Show the structure. (5 pts)
A. It obeys the octet rule on all atoms.
B. It has less than an octet on at least one atom.
C. It has a lone pair of...
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