Everything Science Grade 10

CHAPTER 4. THE ATOM 4.6

1s

2s

3s

2p

3p

Figure 4.10: An Aufbau diagram showing
the electron configuration of fluorine

1s

2s

3s

2p

3p

Figure 4.11: An Aufbau diagram showing

the electron configuration of argon

Tip

The spectroscopic

electron configura-

tion can be written

in shorter form. This

form is written as

[noble gas]electrons,

where the noble gas

is the nearest one

that occurs before

the element. For

example, magnesium

can be represented as

[Ne] 3 s^2 and carbon

as [H] 2 s^22 p^2. This

is known as the

condensed electron

configuration.

Example 3: Aufbau diagrams and spectroscopic electron

configuration

QUESTION

Give the electron configuration for nitrogen (N) and draw an Aufbau diagram.

SOLUTION

Step 1:Give the number of electrons

Nitrogen has seven electrons.

Step 2:Place two electrons in the 1 s orbital

We start by placing two electrons in the 1 s orbital: 1 s^2.

1s

Now we have five electrons left to place in orbitals.

Step 3:Place two electrons in the 2 s orbital

We put two electrons in the 2 s orbital: 2 s^2.

Chemistry: Matter and Materials 83