CH 115 Fall 2014
Worksheet 12
1. Write the name/formula for the following compounds and indicate whether they
are ionic or covalent.
a). Sodium sulfate – ionic, Na2SO4
b). K2Cr2O7 – ionic, potassium dichromate
c). Iron (III) permanganate – ionic, Fe(MnO4)3
d). NH3 – covalent, ammonia
e). Sulfur hexafluoride – covalent, SF6
f). Calcium phosphate – ionic, Ca3(PO4)2
g). Aluminum carbonate – ionic, Al2(CO3)3
h). NaClO3 – ionic, sodium chlorate
i). Cl2O – covalent, dichloride monoxide
j). Ammonium hydroxide – ionic, NH4OH
k). BCl3 – covalent, boron trichloride
2. What does VSEPR stand for and what does it mean? What dictates the geometry of a
particular compound?
Valence shell electron pair repulsion theory – means that the repulsion
occurring between the valence electron pairs on the central atom are causing
what molecular and electronic geometries that we can observe.
3. What is the difference between the electronic (electron-pair) geometry and the
molecular geometry of a compound? Can these two geometries ever be the same for
a particular compound?
Electronic geometry is dictated by all of the regions of electron density around
the central atom. Molecular geometry is the actual shape of the molecule and
takes into account the lone pairs that are present around the central atom.
These two geometries can be the same if there are no lone pairs around the
central atom.
LOOK IN YOUR BOOK FOR A TABLE OF ELECTRONIC AND MOLECULAR
GEOMETRIES AND BOND ANGLES THAT YOU WILL NEED TO HAVE MEMORIZED
FOR THE TEST.
4. Given the formula of a compound, describe how you would determine its electronic
and molecular geometries.
1. Draw the Lewis structure!
2. Count the regions of electron density that surround the central atom
(remember lone pairs count as one, as do double and triple bonds).
3. Decide the electronic geometry based on the number of regions counted.
4. Count the number of lone pairs.
5. Decide the molecular geometry and bond angles based on number of lone
pairs.
CH 115 Fall 2014
Worksheet 12
5. Determine the electronic and molecular geometries respectively for all of the
covalent compounds in question # 1.
d). NH3 – tetrahedral, trigonal pyramidal
e). SF6 – octahedral, octahedral
i). Cl2O – tetrahedral, bent
k). BCl3 – trigonal planar, trigonal planar