SCH4U/R Worksheet
Chemical Structures and Properties Review
1. In diatomic fluorine, F2(g), atoms of fluorine form a covalent bond (the intramolecular force).
a. What atomic orbitals are most likely involved in forming the bond? Draw a diagram showing the overlap
of these atomic orbitals.
b. However, VSEPR theory suggests electrons from the valence shell must minimize repulsion when atoms
form molecules. Given the number of valence electrons around each fluorine, suggest the optimal
electronic shape for each atom in F2(g).
c. Draw the molecule and state the name of the molecular shape for diatomic fluorine.
d. Given this, what type of hybridization must occur for each fluorine atom?
2. Draw the Lewis structure of sulphur trioxide, SO3(g).
a. What is the name of the shape of the sulphur trioxide molecule?
b. How many sigma ()are present in SO3(g) based on your structure? How many pi () bonds are in your
structure?
c. The Lewis structure could be drawn with one double bond between sulphur and oxygen that exists in
resonance (each oxygen takes a turn forming the double bond), but the Lewis structure is most correct if
represented by all three oxygen atoms in a double bond with sulphur simultaneously. Explain why.
3. Selenium tetrafluoride, SeF4(l), is commonly used industrially as a fluorinating reagent.
a. Draw and name the electronic shape of selenium tetrafluoride, SeF4(l). What is the name of the
molecular shape?
b. Draw and name the electronic shape of selenium hexafluoride, SeF6(g). Explain why the molecular shape
name is the same in this case.
c. Based on molecular shape and intermolecular forces, explain why selenium hexafluoride exists as a gas
while selenium tetrafluoride is a liquid.
4. Bromine forms a variety of different compounds depending on what atoms it bonds with and the types of bonds
that are formed. Sodium bromide is a non-toxic, white solid with an extremely high melting point that acts as an
electrolyte, while bromine trifluoride is a toxic, corrosive liquid with a low boiling point that explodes in water.
a. Identify the differences in bonding (intramolecular forces) between these two compounds.
b. Account for the properties exhibited by each compound based on bonding (intra- and intermolecular
forces).
c. In the case of bromine
trifluoride, BrF3(l), fully
explain the hybridization
of bromine.
5. Krypton difluoride, KrF2(l), can be prepared by reacting krypton with fluorine by irradiating the mixture with
ultraviolet rays (Eq. 1).
Equation 1
Kr(g)
+
F2(g)

KrF2(s)
a.
b.
c.
d.
e.
Draw the Lewis structure of KrF2 and predict the hybridization required for krypton in KrF2.
Give the electron configuration of krypton.
Describe which electrons and orbitals are involved in the hybridization.
Name and draw the molecular shape of KrF2.
Explain why the lone pairs are arranged in the equatorial positions while the bond pairs to fluorine are in
the axial positions.
6. Methanamine and methanol are both organic compounds used as reagents for many chemical reactions.
CH3NH2
methanamine
CH3OH
methanol
In both cases, if the carbon atom is considered the central atom, the molecular shape will be tetrahedral.
a. Using the nitrogen atom as the central atom, draw and name the electronic shape and the molecular shape
of methanamine, CH3NH2.
b. Using the oxygen atom as the central atom, draw and name the electronic shape and the molecular shape
of methanol, CH3OH.
c. The boiling point of methanamine is -6oC, while methanol boils at 65oC. Completely explain this difference
based on intermolecular forces.