Station 1
(This bond is Long and Strong, and it’s down to get the friction on!)
1) Answer the following questions about the element selenium, Se (atomic
number 34).
a) Write the electron configuration (e.g., 1s2 2s2... etc.) for a selenium atom
in the ground state. Indicate the number of unpaired electrons in the
ground-state atom, and explain your reasoning.
b) In terms of atomic structure, explain why the first ionization energy of
selenium is
(i) less than that of bromine (atomic number 35), and
(ii) greater than that of tellurium (atomic number 52).
c) Selenium reacts with fluorine to form SeF4. Draw the complete Lewis
electron-dot structure for SeF4 and sketch the molecular structure.
Indicate whether the molecule is polar or nonpolar, and justify your
answer.
2) Put each of the following series in order of increasing size:
a) Al3+, N3-, O2-, Ar, Li+
b) K, Na, Sr, Na+, P33) Put the following in order of increasing C-C bond length:
C2 Cl3F3, C2HCl, C2F3Cl
4) Put the following in order of increasing C-C bond strength:
C2 Cl3F3, C2HCl, C2F3Cl
5) Using principles of chemical bonding and molecular geometry explain each of
the following observations. Lewis electron-dot diagrams and sketches of
molecules may be helpful as part of your explanations. For each observation
your answer must include references to both substances.
(a) The bonds in nitrite ion, NO2-, are shorter than the bonds in nitrate
ion, NO3-.
(b) The CH2F2 molecule is polar, whereas the CF4 molecule is not.
(c) The atoms in a C2H4 molecule are located in a single plane, whereas
those in a C2H6 molecule are not.
(d) The shape of a PF5 molecule differs from that of an IF5 molecule.
Station 2
(Get in “shape”)
1) (a) Draw the Lewis electron-dot structures for CO32-, CO2,
and CO, including resonance structures where appropriate.
(b) Put the three species in order of increasing C-O bond
length? Explain the reason for your answer.
(c) Predict the molecular shapes for the three species.
2)For each of the following molecules:





Draw a Lewis electron-dot structure
identify the shape
Determine the hybridization for the central atom
Identify the number of sigma bonds and pi bonds
Determine if the molecule is polar or nonpolar or ion
a)
CF4
f)
CH3F
b)
XeF4
g)
H2O
c)
ClF3
h)
BrH5
d)
ClO2-
i)
NH3
e)
SeF4
j)
PO33-
Station 3
(Skyfall Energy)
1) Determine the equation that represents the following.
Sign of ∆H
Lattice Energy Barium Fluoride
First ionization energy of Ba
Second ionization energy of Ba
Electron affinity of F
Bond energy of F2
Enthalpy of sublimation of Ba
2) The following reaction represents the synthesis of Mustard Gas. The incomplete structure of mustard gas is
shown. Draw the complete Lewis structures for each reactant. Using the table of bond energies, calculate the
∆Hf˚ for the
Bond
D
(kJ/mol)
H-H
432
H-C
411
H-S
363
H-O
459
H-Cl
428
C-C
346
C=C
602
C≡C
835
C-N
305
C=N
615
C≡N
887
C-O
358
C=O
799
C≡O
1072
C-S
272
C=S
573
C-Cl
327
S=O
522
S-S (S8)
226
S=S
425
S-F
284
S-Cl
255
O=O
495
SCl2 + 2 C2H4
→
(ClC2H4)2S
S
Cl
3) Using the table of bond energies, determine the ∆Hf˚ for the complete
combustion of C3H6 (propene).
Cl
Station 4
(Get your popcorn, peanuts, coffee, energy, and brain damage causing drugs HERE!)
For each molecule shown, determine all bond angles (red), hybridization of the atoms (blue), and the
number of sigma and pi bonds.
Furylmethanthiol (coffee aroma)
Methylenedioxymethamphetamine (Ecstasy)
Methyl 2-pyridyl Ketone (popcorn)
2-methoxy-5-methyl Pyrazine (peanuts)