Atomic Structure - Chemistry - page 71

The Four Quantum Numbers

Called
Principal
Angular
momentum
Magnetic
Spin

Symbol
n
l

Indicates
Energy Level
Sublevel

Values*

First Quantum Number
Second Quantum Number

1-7
0, 1, 2, 3 (or s, p, d, f)

Third Quantum Number
Fourth Quantum Number

M l
M s

Orbital
Electron

+3, +2, +1, 0, -1, -2, -3
+1/2 and -1/2

* There are other possible values, but the listed values will cover all that you
need to use for the elements that are currently known.

Figure 3-3a

The information that we have covered on quantum numbers will be
used to construct a type of notation called the electron configurations of
elements in the next chapter. You will want to be able to remember how
many sublevels, and which types, are found in each energy level. I ask my
students to remember a simple sentence such as, “some people don't for-
get” to help them recall the order of the sublevels. To recall which sublev-
els the third energy level has, for example, they might say to themselves,
“some people don't.”
Also remember that each orbital can hold up to two electrons and that
the sublevels contain different numbers of orbitals. The number of sublev-
els, orbitals, and electrons that the first four energy levels hold is summa-
rized in Figure 3-3b.
Remember: Each orbital can hold up to two electrons, so a p sublevel,
which contains 3 orbitals, can hold up to 6 electrons (2 electrons × 3 orbit-

als). To find out how
many total electrons
a certain energy
level can hold, you
can do one of two
things. First, you
could add up the to-
tal number of elec-
trons that each of its
sublevels can hold.
For example, the
fourth energy level
has four sublevels (s,
p, d, and f), which

Summary of the First Four Energy Levels
Type(s) of
Sublevel
s
s
p
s
p
d
s
p
d
f

Principal Energy
Level (n)
1

Number of
Orbitals
1
1
3
1
3
5
1
3
5
7

Maximum Number
of Electrons
2
2
6
2
6
10
2
6
10
14

2

3

4

Figure 3-3b