Chemistry Reference
In-Depth Information
Determine the proper ground state electron configuration for the fol-
lowing elements.
5. Potassium
6. Krypton
Lesson 3-5: Orbital Notation
The orbital notation of an element is related to the electron configura-
tion, and both types of notation are often shown at the same time. The real
difference in the two types of notation has to do with the level of detail
shown. In electron configuration, no details are shown about the actual
orbitals. When we see “3p
4
,” we know that there are 4 electrons in the p
sublevel, but we don't know in which orbitals the electrons are located.
When we do the orbital notation for the element, we get that level of detail
for the orbitals.
The first step for doing the orbital notation is to do the electron con-
figuration. You will then want to remember Hund's Rule, which states that
the most stable arrangement of electrons in sublevels is the one with the
greatest number of parallel spins. The way that we make use of this rule is
to put one electron in each of the orbitals in a particular sublevel, before
we double up the electrons in any particular orbital.
When we write an orbital notation, the orbitals are represented by circles
or squares, and the electrons are represented by arrows or slashes. For the
sake of clarity, the orbital notation is usually accompanied by the proper
electron configuration.
One last thing: In order to do orbital notation, you must be able to do
electron configuration. So, if you haven't mastered Lesson 3-4, you should
go back and do more practice.
Let's try an example.
Example 1
Write the proper orbital notation for an atom of aluminum.
The first thing that we need to do is find the electron configuration for
aluminum. Because we did this example in the last lesson, I won't go through
the steps. Refer back to the last lesson if you don't remember how to do
this. We will space the configuration out a bit more this time, so that we
have room to write the orbital notation.
1s
2
2s
2
2p
6
3s
2
3p
1
