Chem452/552 Inorganic Chemistry ------------------Point Group Name: _________________ 1. Indicate by ci rcling whether each of the following statements is true or is false.  

True False There are five mirror planes present in a square. True False There are five proper rotation axes present in a square. True False There is an inversion center in a square. True False A scalene triangle has only the identity operation as a

symmetry element. True False A linear molecule such as CO2 has only one rotation axis that

runs the length of the molecule.

2. Complete the following table by filling in the spaces with the symmetry

elements/operations present in the given chemical species. Do not simply indicate the presence or absence of the element/operation but give detailed information, i.e., if a proper rotation axis is present, the indicate type (C2, C3, etc). If the particular element/operation is not present in the specie, then leave the space empty.

  Identity

(E) Proper

Rotation Axes (C)*

Mirror planes

( )

Inversion Center

(i)

Improper Rotation Axes (S)**

SeF2

BHCl2

SiHCl3

[SF5]-

KrF4

SiH2Cl2

SiH3Cl

SiH4

SF6

 *Circle the principal axis if more than one rotation axis is present. **Identify only those that are unique in the object, i.e., do not identify improper rotation axes that are coincidental with proper rotation axes.

3. Enter into the smaller box the point group for each of the following species and then list in the larger box the symmetry elements and operations that were instrumental in the determination of the point group (do not list all such things, only the key ones needed to determine the point group. p-dichlorobenzene

Point Group:

Symmetry elements and operations:

m-dichlorobenzene

Point Group:

Symmetry elements and operations:

o-dichlorobenzene

Point Group:

Symmetry elements and operations:

Aluminum containing species shown at bottom of page

Point Group:

Symmetry elements and operations:

Elemental arsenic structure shown at bottom of page (note: all As-As bonds equal in length)

Point Group:

Symmetry elements and operations:

Octahedral Cr compound shown at bottom of page - heavy atom symmetry only (ignore H's)

Point Group: Symmetry elements and operations:

AlC

H

H

H

O As

As

AsAs

NH3

Cr

O

NH3

O

PO

NH3

NH3

boron trifluoride

Point Group:

Symmetry elements and operations:

cyclopropane

Point Group:

Symmetry elements and operations:

propyne

Point Group:

Symmetry elements and operations:

carbon dioxide

Point Group:

Symmetry elements and operations:

iodine pentafluoride

Point Group:

Symmetry elements and operations:

cyclohexane (boat)

Point Group:

Symmetry elements and operations:

hydrogen cyanide Point

Group:

Symmetry elements and operations:

indium trichloride

Point Group:

Symmetry elements and operations:

1,1'-dibromocyclopropane

Point Group:

Symmetry elements and operations:

phenylacetylene

Point Group:

Symmetry elements and operations:

carbon oxysulfide

Point Group:

Symmetry elements and operations:

1-iodonaphthalene Point

Group:

Symmetry elements and operations:

cyclohexane (chair) Point

Group:

Symmetry elements and operations:

PCl4+

Point Group:

Symmetry elements and operations:

cis-1,2-dibromocyclopropane

Point Group:

Symmetry elements and operations:

SiH2Cl2

Point Group:

Symmetry elements and operations:

BeBr2

Point Group:

Symmetry elements and operations:

BrF4

- Point Group:

Symmetry elements and operations:

1,3,5-trichlorobenzene Point

Group:

Symmetry elements and operations:

cumulene (not cumene or isopropylbenzene)

Point Group:

Symmetry elements and operations:

trans-1,2-dibromocyclopropane

Point Group:

Symmetry elements and operations:

oxalate ion (planar configuration)

Point Group:

Symmetry elements and operations:

Cl2

Point Group:

Symmetry elements and operations:

Chrysene

Point Group:

Symmetry elements and operations:

1,2,3-trichlorobenzene Point

Group:

Symmetry elements and operations: