Chemistry Reference
In-Depth Information
Sublevel Summary
Sublevel
Number of orbitals it contains
(first 4 odd numbers)
1
3
5
7
Total number of electrons it can hold
(2 × the number of orbitals)
2
6
10
14
s
p
d
f
Figure 3-4e
Now, you should have all of the tools that you need to do the electron
configuration. Become familiar with the steps shown here for writing the
electron configuration of an element, and then we will review them.
1.
Look up the atomic number of the element.
2.
Determine the number of electrons for the specific element.
A.
If the atom is neutral, then the number of electrons is equal to
the number of protons.
B.
If the atom is charged, then algebraically subtract the charge
from the atomic number of the element. (Example 1: The atomic
number of sodium is 11. An ion of Na+ would have a total of
11 - 1 = 10 electrons. Example 2: The atomic number of sulfur
is 16. An ion of S
2-
would have 16 - (-2) = 18 total electrons.)
3.
Consult the arrow diagram to determine the order in which the sub-
levels should be filled.
4.
Write the configuration, filling in up to 2 electrons in each “s” sublevel,
up to 6 electrons in each “p” sublevel, up to 10 electrons in each “d”
sublevel, and up to 14 electrons in each “f” sublevel.
5.
When you think that you are finished, add up the exponents (super-
scripts) to see if you have the correct number of electrons.
Let's do an example.
Example 1
Write the full electron configuration for the element neon (Ne).
Step 1. Look up the atomic number of the element. The periodic table shows
us that the atomic number of neon is 10.
Step 2. Determine the number of electrons for the specific element.
