Electron Configuration Practice Worksheet
In the space below, write the unabbreviated electron configurations of the
following elements:
1)
sodium ________________________________________________
2)
iron
________________________________________________
3)
bromine
________________________________________________
4)
barium
________________________________________________
5)
neptunium
________________________________________________
In the space below, write the abbreviated electron configurations of the following
elements:
6)
cobalt
________________________________________________
7)
silver
________________________________________________
8)
tellurium
________________________________________________
9)
radium ________________________________________________
10)
lawrencium
________________________________________________
Determine what elements are denoted by the following electron configurations:
11)
1s22s22p63s23p4 ____________________
12)
1s22s22p63s23p64s23d104p65s1 ____________________
13)
[Kr] 5s24d105p3 ____________________
14)
[Xe] 6s24f145d6 ____________________
15)
[Rn] 7s25f11 ____________________
Determine which of the following electron configurations are not valid:
16)
1s22s22p63s23p64s24d104p5 ____________________
17)
1s22s22p63s33d5 ____________________
18)
[Ra] 7s25f8 ____________________
19)
[Kr] 5s24d105p5 ____________________
20)
[Xe] ____________________
Electron Configurations - Solutions
Note: The electron configurations in this worksheet assume that lanthanum (La)
is the first element in the 4f block and that actinium (Ac) is the first element in the
5f block. If your periodic table doesn’t agree with this, your answers for elements
near the f-orbitals may be slightly different.
1)
sodium 1s22s22p63s1
2)
iron
1s22s22p63s23p64s23d6
3)
bromine
1s22s22p63s23p64s23d104p5
4)
barium
1s22s22p63s23p64s23d104p65s24d105p66s2
5)
neptunium
1s22s22p63s23p64s23d104p65s24d105p66s24f145d106p67s25f5
6)
cobalt
[Ar] 4s23d7
7)
silver
[Kr] 5s24d9
8)
tellurium
[Kr] 5s24d105p4
9)
radium [Rn] 7s2
10)
lawrencium
11)
1s22s22p63s23p4 sulfur
12)
1s22s22p63s23p64s23d104p65s1 rubidium
13)
[Kr] 5s24d105p3 antimony
14)
[Xe] 6s24f145d6 osmium
15)
[Rn] 7s25f11 einsteinium
16)
1s22s22p63s23p64s24d104p5 not valid (take a look at “4d”)
17)
1s22s22p63s33d5 not valid (3p comes after 3s)
18)
[Ra] 7s25f8 not valid (radium isn’t a noble gas)
19)
[Kr] 5s24d105p5 valid
20)
[Xe] not valid (an element can’t be its own electron configuration)
[Rn] 7s25f146d1
Atomic Orbitals and Electron configurations
The BIG idea: four types of atomic orbitals emerge from the solutions to the Schrödinger
equation.
Each type is a different shape. Electrons fill these orbitals to build up the structure of an
atom until the
number of electrons is equal to the number of protons in the nucleus. The orbitals fill in a
predictable
way, following a pattern that can be traced on the periodic table. This is the essential
information we
need to understand why elements have various chemical properties.
The ground rules:
1. Each row or period in the periodic table represents an energy level (1 through 7).
These levels are
often designated by the letter n (called the principal quantum number).
Thus H and He have electrons in level n = 1.
Li, Be, B, C, N, O, F and Ne have electrons in levels n = 1 and n = 2.
Na, Mg, Al, Si, P, S, Cl and Ar have electrons in levels n = 1, n = 2 and n = 3.
Get the idea?
2. Each orbital (regardless of type) may contain 1 or 2 electrons but no more.
3. The number of types of orbitals is equal to n. The total number of orbitals on an energy
level is equal
to n2.
4. The types of orbitals are: s, p, d, f. These are listed in order of increasing energy within
an energy
level (i.e., energy levels have sub-levels).
Thus on n = 1, there is only one s orbital.
On n = 2, there is an s orbital and three p orbitals.
On n = 3, there is an s orbital, three p orbitals and five d orbitals.
On n = 4 and higher there is an s orbital, three p orbitals, five d orbitals and seven f
orbitals.
[the result of this progression is that there can only be one s orbital on a level, three p
orbitals, five d
orbitals, and seven f orbitals]
The easier way
All of this information is summarized neatly in the periodic table if you learn to read it
correctly. The
first two columns of the table consist of s-orbitals. The last six are p-orbitals, the middle
10 are dorbitals,
and the bottom two rows are f-orbitals. The diagram below summarizes this information.
The electron structure surrounding the nucleus is of prime importance in understanding
the chemistry of
the elements. This structure can be read directly off the periodic table and expressed in
abbreviated
form. Some examples follow:
H 1s1
He 1s2
Li 1s22s1
Be 1s22s2
B 1s22s22p1
C 1s22s22p2
N 1s22s22p3
O 1s22s22p4
F 1s22s22p5
Ne 1s22s22p6
Na 1s22s22p63s1 OR [Ne]3s1
Note: although the first d-orbitals appear on the periodic table in row 4, they are called
3d orbitals. Thus
the entire d-section of the table is numbered one less than the row in which it appears. A
similar offset
occurs for the f-orbital block, but it is two numbers less.
Electron Configuration Worksheet
1. Explain what each number and letter means in the following notation: 3p6
2. Determine the following for the 4th electron shell (4th main energy level) of an atom.
a) The number of subshells it contains.
b) The designation used to describe each of the first three subshells.
c) The number of orbitals in each the first three subshells.
d) The maximum number of electrons that can occupy the 4th electron shell.
e) The maximum number of electrons that can occupy each of the first three
subshells.
3. Fill in the numerical value(s) that correctly complete(s) each of the following
statements.
a) A 5f subshell holds a maximum of ______ electrons.
b) A 4s orbital holds a maximum of ______ electrons.
c) The maximum number of electrons in the third electron shell is ______.
d) The forth shell contains ______ subshells, ______ orbitals, and a maximum
of ______ electrons.
4. Give the maximum number of electrons that can occupy each of the following units.
a) 2p subshell
shell
b) 5d orbital
c) 3s orbital
d) 5d subshell
e) Fifth
5. Name the elements whose electron configurations are:
a)
1s2 2s2 2p6 3s2 3p6 4s2 3d3
b)
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d9
6. Write electron configurations for these elements:
a)
Copper
b)
Bromine
ANSWERS
1)
“3”= energy level, “p” = subshell designation, “6” = number of electrons
2a)
4
2b)
4s, 4p, 4d
2c)
1, 3, 5
2d)
32
2e)
2, 6, 10
3a)
14
3b)
2
3c)
18
3d)
4, 16, 32
4a)
6
4b)
2
4c)
2
4d)
10
4e)
50
5a)
Vanadium
5b)
Silver
6a)
1s2 2s2 2p6 3s2 3p6 4s2 3d9
6b)
1s2 2 s2 2p6 3s2 3p6 4s2 3d10 4p5