Practice with Electron Configurations
Prelab Assignment
Read the entire lab and write an objective and possible hazards in your laboratory
notebook. Answer the following questions in your laboratory notebook before coming to
lab. You will have to use your textbook and lecture notes to answer these questions.
1. State Pauli’s exclusion theory.
2. State the aufbau principle.
3. Describe how the n and l quantum numbers are used in determining the order
in which electrons are assigned to orbitals as you move across and then down
the periodic table. In other words how the n and l quantum numbers are used
to estimate the energy of a subshell.
4. State Hund’s Rule.
5. The following is the condensed electron configuration of the element sulfur:
[Ne]3s23p4. Answer the following questions based on this representation for
the electron configuration of sulfur.
a. Identify what each letter, number, and symbol in the representation of
sulfur’s electron configuration shown above tells us.
b. How many total electrons does the element sulfur have and how can
you tell this from the above representation?
c. How many valence electrons, or outer electrons that may participate in
chemical reactions, does the element sulfur have and how can you tell
this from the above representation?
d. What period does the element sulfur lie in and how can you tell this
from the above representation?
e. What group does the element sulfur lie in and how can you tell this
from the above representation?
6. The following is the orbital box notation for the electron configuration of the
element sulfur: [Ne] ↑↓ ↑↓ ↑__ ↑__ .
3s
3p.
Answer the following questions based on this representation.
a. Identify what each letter, number, and symbol in the representation of
sulfur’s electron configuration shown above tells us.
b. How many total electrons does the element sulfur have and how can
you tell this from the above representation?
c. How many unpaired electrons does sulfur have and how can you tell
this from the above representation?
d. Do you expect sulfur to be para- or diamagnetic and why?
7. Sketch the periodic table indicating the locations of the s, p, d and f blocks.
Procedure:
1. Depict the condensed electron configurations of the following elements: Li, Be, B, C,
N, O, F, Ne, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Kr, Cs, La, Ce, U,
Au, Pb, and Rn. Please complete these electron configurations without looking at
online sources and then use an on-line source to check your work. Be cautious of online periodic tables. Only use tables consistent with the International Union of Pure
and Applied Chemistry, IUPAC, and National Institute of Standards and Testing,
NIST, recommendation that La and Ac be in the d-block rather than the f-block. You
may use websites such as http://www.rsc.org/periodic-table or
http://www.nist.gov/pml/data/periodic.cfm to check your work. In order to learn
from this lab and be prepared for quizzes and exams you must complete the electron
configurations yourself first and then use the web to check your work. If you simply
copy the answers from the web you will not be prepared for exams in this course
or for entrance exams such as the MCAT, PCAT or GRE.
Li
Be
B
C
N
O
F
Ne
K
Ca
Sc
Ti
V
Cr
Mn
Fe
Co
Ni
Cu
Zn
Ga
As
Kr
Cs
La
Ce
U
Au
Pb
Rn
2. The elements Ne, Kr, and Rn are noble gases. Examine the electron
configurations you have depicted for these elements. What aspect of their
electron configurations’ do these three elements have in common? How might
this common feature in Ne, Kr, and Rn’s electron configuration explain the octet
rule?
3. You depicted the electron configurations for elements in the 2nd, 4th and 6th rows
of the periodic table. Examine your depictions of the electron configurations for
the elements in these rows and describe the relationship between elements’ n
value, their row in the periodic table, and their block in the periodic table. In
other words what is the relationship between the n value for elements in the s and
p block and the row they are in. What is the relationship between the d block
elements and the row they are in, and so forth. Also read section 7.8 titled “The
Periodic Table and Filling the Orbitals of Multielectron Atoms” in your textbook.
4. Examine the electron configurations for the elements Cr, Cu, and Au. Do these
elements have the electron configurations you expect? How do the electron
configurations for these elements differ from the configurations you expected for
these elements? Read section 7.8 titled “The Periodic Table and Filling the
Orbitals of Multielectron Atoms” in your textbook.
5. Use condensed orbital box notation to depict the electron configurations of the
following elements: Li, Be, B, C, N, O, F, Ne, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni,
Cu, Zn, Ga, As, Kr, Cs, La, Ce, U, Au, Pb, and Rn. Complete these electron
configurations without looking at online sources and then use an on-line source to
check your work. Be cautious of on-line periodic tables. Only use tables consistent
with the International Union of Pure and Applied Chemistry, IUPAC, and National
Institute of Standards and Testing, NIST, recommendation that La and Ac be in the dblock rather than the f-block. You may use websites such as
http://www.rsc.org/periodic-table or http://www.nist.gov/pml/data/periodic.cfm to
check your work. In order to learn from this lab and be prepared for quizzes and
exams you must complete the electron configurations yourself first and then use the
web to check your work. If you simply copy the answers from the web you will not
be prepared for exams in this course or for entrance exams such as the MCAT, PCAT
or GRE.
Li
Be
B
C
N
O
F
Ne
K
Ca
Sc
Ti
V
Cr
Mn
Fe
Co
Ni
Cu
Zn
Ga
As
Kr
Cs
La
Ce
U
Au
Pb
Rn
6. Examine the electron configurations for the elements Cr, Cu, and Au. Do these
elements have the electron configurations you expect? Read page 349 in your
textbook. Explain why these elements do not follow the expected trend.
7. Examine the orbital box and spdf notations for the electron configurations you
completed in problems 1 and 5 above. What are the advantages of each type of
notation?
8. Li forms the cation Li+ while F forms the anion F-. Use the orbital box notations
for the electron configurations of Li, F, Li+, and F- to explain why each of these
elements forms the ions they do.
9. Cu may form the cations Cu+ and Cu2+. Use the orbital box notations for the
electron configurations of Cu, Cu+ and Cu2+ to explain why copper may form both
the Cu+ and Cu2+ cations. Note that the elements nickel and zinc commonly form
cations with +2 charges.
10. Use the orbital box notations for the electron configurations of Cr3+ and Cr6+ to
predict which cation is more strongly attracted to a magnet.