Hund’s Rule Investigation
Chem. 319
Ms. Hobbie
There are two important facets of Hund’s Rule:
1.
Each orbital in an energy sublevel is occupied by a single electron before any orbital is doubly
occupied.
2. All electrons in singly-occupied sublevels (unpaired electrons) will have spins in the same direction.
Draw shorthand orbital notation diagrams (arrows) of the following elements, keeping Hund’s rule in mind.
25Mn
26Fe
27Co
28Ni
29Cu
30Zn
Background
Wolfgang Pauli discovered that electrons in an atom are spinning.
Physics tells us that moving charges create magnetic fields.
The arrows above represent electrons that are spinning; therefore…
 each electron represents a moving charge.
 each electron is a little magnet.
Definitions to ponder
What is the difference a paramagnetic substance and a diamagnetic substance? (P. 328 might be useful…)
Create a hypothesis
By looking at the orbital diagrams you have drawn above for these six elements, consider these questions:
 Which of these elements will be diamagnetic?
 Of the paramagnetic elements, which will have the greatest attraction towards a magnetic field?
Experiment
Record the mass of the compound containing the metal atoms of interest, both alone and when beneath a
suspended magnet. Calculate the difference in mass and the percent of the sample’s mass that is reduced by the
presence of the magnet
Element
DATA
Mass w/o
Mass with
Magnet (g)
Magnet (g)
CALCULATIONS
Difference
% Difference
in Mass (g)
in Mass
CLASS DATA
Element
% Difference
in Mass
25Mn
26Fe
27Co
28Ni
29Cu
30Zn
Analysis
Explain how Hund’s rule is supported by the findings in this experiment.