ELECTRON CONFIGURATIONS & THE MAGNETIC PROPERTIES OF MATTER
oven
detector
slit
N
S
magnet
47Ag:
n =
l =
ml =
ms
1s
1
0
0
2s
2
0
0
2p
2
1
-1 0 +1
+½ -½
+½ -½
+½ +½ +½
1s
2s
2p
Quantum numbers for each electron in a nitrogen atom:
1st electron: n = 1, l = 0, ml = 0, ms = +½
5th electron: n = 2, l = 1, ml = –1, ms = +½
2nd electron: n = 1, l = 0, ml = 0, ms = –½
6th electron: n = 2, l = 1, ml = 0, ms = +½
rd
3 electron: n = 2, l = 0, ml = 0, ms = +½
7th electron: n = 2, l = 1, ml = +1, ms = +½
4th electron: n = 2, l = 0, ml = 0, ms = –½
Materials
Neodymium (Nd) magnet, triple-beam balance, vials containing copper (II) chloride, CuCl2, iron
(III) chloride, Fe2Cl3, cobalt (II) nitrate, Co(NO3)2, and calcium chloride, CaCl2.
Pre-lab Activity:
1. For each metallic element in the compounds studied, write the electron configuration in
the space provided. For example, the electron configuration for sodium, 11Na (atomic
number 11), would be 1s2, 2s2, 2p6, 3s1. NOTE: The order in which the electrons fill the
sublevels in copper is an exception to the order of increasing energy studied. That is, in
copper, the 3d sublevel is completely filled before any electrons are added to the 4s
sublevel.
20Ca
___________________________________
26Fe
___________________________________
27Co
___________________________________
29Cu
___________________________________
2. Using the electron configurations above, write the orbital notations for each metallic
element. The zero superscript indicates that there is no charge on the atom (that is, it has
not lost any electrons to become an ion).
20Ca
26Fe
0
1s
2s
2p
3s
3p
4s
3d
1s
2s
2p
3s
3p
4s
3d
1s
2s
2p
3s
3p
4s
3d
1s
2s
2p
3s
3p
4s
3d
0
27Co
0
0
29Cu
3. For each metal ion contained in the chemical compounds studied, give its orbital notation
from its charge in the space provided below:
Which electrons are removed when an atom forms a positive ion? The electrons in the
highest energy level are removed first. (The last electrons to be placed are the first to be
removed.)
20Ca
26Fe
2+
1s
2s
2p
3s
3p
4s
3d
1s
2s
2p
3s
3p
4s
3d
1s
2s
2p
3s
3p
4s
3d
1s
2s
2p
3s
3p
4s
3d
3+
27Co
2+
2+
29Cu
Procedure:
1. Place the neodymium magnet on the triple beam balance pan and “tare” (zero) the balance.
2. Bring one of the vials containing an ionic compound as close to the magnet as possible
without touching the magnet. Note the direction and degree of movement of the arm on the
triple beam balance in the data table below. Also note the color of the compound in the vial.
3. Repeat Step 2 for all the samples.
Data Table
Compound
Color
# of
unpaired
electrons
Attracted or repelled
by magnet?
Relative degree of
arm movement
(most – least)
Calcium chloride
Iron (III) chloride
Cobalt (II) nitrate
Copper (II) chloride
Analysis Questions
1. Compare the orbital notations of the substances investigated in this experiment with
their attraction to the magnet. What unique feature in the orbital notation could be used to
predict an attraction to a magnet? Explain your answer.
2. Compare the orbital notations of the substances studied in this experiment. What is the
relationship between the strength of their magnetic attraction and their orbital notation?
3. Assign a set of four quantum numbers (n, l, ml, and ms) for the outermost electron in each of
the metallic ions studied in this activity.
4. The element chromium has three common oxidation states, Cr0, Cr3+, and Cr6+.
(a) Write the orbital notation for the three common oxidation states of chromium. (*The
electron configuration of Cr0 is an exception to the Aufbau order. Its electron
configuration ends 4s1 3d5, instead of the expected order, 4s2 3d4.)
(b) Substances which are attracted to a magnet are said to be paramagnetic. Which of the
different oxidation states of chromium would you expect to be paramagnetic and
why?
5. One of the scientific principles applied when writing orbital notations is Hund’s rule.
Hund’s rule states that “the most stable arrangement of electrons is that with the
maximum number of unpaired electrons, all with the same spin direction.” Explain
briefly how your experiment supports Hund’s rule.