Name: _______________________
Date: _______________________
C3
demonstrate an understanding of atomic structure and chemical bonding, and how they relate to the physical properties of ionic, molecular,
covalent network, and metallic substances
Quantitative Paramagnetism: Studying Electron Configurations
Purpose: To investigate the relationship between atomic structure and paramagnetism.
Abstract
Known masses of ionic compounds composed of alkaline earth and transition metal ions are placed into large, stoppered
test tubes. The test tubes are lowered to the same height above a centigram balance that has been zeroed with
neodymium magnets placed on the scale. As the test tube is lowered toward the neodymium magnets, the magnets will
be attracted to paramagnetic compounds and cause the mass reading to reduce. The reduction in scale readings for
each sample of ionic compound is recorded and evaluated against the number of unpaired electrons in the metal ion of
the sample compound.
Materials
6 large test tubes and stoppers
milligram balance
wooden block
retort stand
3.0 g samples of various ionic compounds
neodymium magnets
2-prong clamp
Observations
Data Table 1 Reductions in scale reading compared to unpaired electrons in metal ion
# of unpaired
Moles of
Sample
Metal Electron configuration in
Molar mass
electrons in
compound
compound
ion
the d sublevel
(g/mol)
metal ion
(mol)
mass
reading
(g)
CaSO4.2H2O
0.00
MnSO4.H2O
-1.26
FeSO4.7H2O
-0.51
NiSO4.7H2O
-0.22
CuSO4.5H2O
-0.09
FeCl3.6H2O
-0.95
CoCl2.6H2O
-0.47
mass
per mole
(g/mol)
Analysis
1. Identify the metal ion in each compound (noting the valence). Write the electron configuration of the metal ion.
2. Record the number of unpaired electrons in the d sublevel of the metal ion.
3. Calculate the number of moles of each compound given that 3.0 g was used.
4. Calculate the change in the mass reading in each case per mole of compound.
5. Plot a graph of the number of unpaired electrons versus the change in mass per mole. Draw a line of best fit.
Discussion
1. How does the change in mass relate to paramagnetic strength? Explain.
2. Describe the relationship between the number of unpaired electrons and paramagnetic strength.