CHEM 1A  Lecture Quiz 2 • Spring 2014
Name:_________________________________________
1. Write the COMPLETE electron configuration for the selenide anion, Se2-.
2. Following the Aufbau Principle, Hund’s rule & the Pauli Exclusion Principle, fill in the electron orbital
diagram (below) for neutral SULFUR in its ground state. LABEL EACH SUBSHELL.
Not all subshells may necessarily be filled with electrons.
3. How many VALENCE electrons does a neutral arsenic (As) atom have?
4. How many CORE electrons does a neutral iodine (I) atom have?
5. The table below reports successive ionization energies for an element in PERIOD 3 of the periodic
table. What is the likely identity of this element?
Ionization Energies (kJ/mol)
Unknown Element
IE1
IE2
IE3
IE4
IE5
IE6
IE7
787 1575 3229 4350 16100 19800 23800
6. Circle the electron orbital below that would be the BEST at shielding outer electrons from the nucleus.
BRIEFLY explain your choice.
7. Rank these neutral atoms from SMALLEST to LARGEST: Al, Cs, F, P, Sr
SMALLEST: _______
_______
_______
3-
_______
2+
2+
8. Rank these ions from SMALLEST to LARGEST: As , Ca , Mg , Sb
SMALLEST: _______
_______
_______ : LARGEST
3-
_______
_______ : LARGEST
9. Based on Coulomb’s Law, circle the ionic compound below expected to have the SMALLEST lattice
energy. In other words, which ionic compound would have the smallest positive U value. Briefly
explain your reasoning.
BaI2
SrBr2
CaCl2
CaBr2
MgCl2
MgS
10. Which of the compounds in question 9 (above) would have the HIGHEST expected melting point?
Briefly explain your reasoning.
For the next two questions, consider the 4 reactions, A. through D. below.
A. Br2-(g) + 1 e- → Br3-(g)
B. Br+(g) + 1 e- → Br(g)
C. Br(g) + 1 e- → Br-(g)
D. Br-(g) + 1 e- → Br2-(g)
11. Rank these reactions based on their expected changes in energy (ΔE), from MOST NEGATIVE ΔE to
MOST POSITIVE ΔE.
MOST NEGATIVE ΔE: _______
_______
_______
_______ : MOST POSITIVE ΔE
12. Which of the reactions above (A.-D.) would correspond to the first electron affinity of bromine?
13. Which covalent bond below would be the MOST POLARIZED? FOR THIS BOND ONLY, write the
appropriate symbols to indicate the partial negative and partial positive ends of the bond.
C—H
N—H
O—H
F—H
N—F
O—F
14. Write the Lewis dot structure for HCCCH3.
15. Assuming chlorine is in the center, draw the lowest energy Lewis dot structure for chlorate, ClO3-.
Draw ALL resonance structures for this lowest energy depiction of chlorate.
16. Of the structures drawn below, circle the BEST Lewis dot structure for the thiocyanate anion, SCN-.
Briefly explain your choice by discussing the octet rule & formal charge.
17. The Lewis dot structure of dinitrogen tetroxide is drawn below. Calculate and write the formal charge
next to each atom.
18. What would be the OVERALL charge of this chemical species?
19. A red ruby stone containing only aluminum and oxygen was analyzed chemically and found to contain
52.925 % aluminum by mass. Based on this mass composition, what is the empirical formula for this
mineral? Show your complete work for full credit.
EXTRA CREDIT: 5 points
Based on the information below, calculate the lattice energy (U) of solid calcium oxide.
Reference Information:
st
1 Ionization Energy of Calcium: +589.8 kJ/mol
2nd Ionization Energy of Calcium: +1145.4 kJ/mol
3rd Ionization Energy of Calcium: +4912.4 kJ/mol
Sublimation Energy of Calcium Metal: +177.8 kJ/mol
1st Ionization Energy of Oxygen: +1313.9 kJ/mol
2nd Ionization Energy of Oxygen: +3388.3 kJ/mol
3rd Ionization Energy of Oxgyen: +5300.5 kJ/mol
1st Electron Affinity of Oxygen: -142 kJ/mol
2nd Electron Affinity of Oxygen: +844 kJ/mol
Bond Energy of O—O Single Bond: +146 kJ/mol
Bond Energy of O=O Double Bond: +495 kJ/mol
Ca(s) + ½ O2(g) → CaO(s) ΔE = -634.9 kJ/mol