# Potassium is highly reactive metal, while argon is an inert gas. How can you explain this difference based on their electron configurations?

##### 1 Answer
May 31, 2018

Potassium needs to lose an electron to achieve noble gas configuration, while argon already has noble gas configuration.

#### Explanation:

Here are the positions of potassium and argon on the periodic table:

From this, we can see that:

• Potassium's full electronic configuration is $1 {s}^{2} 2 {s}^{2} 2 {p}^{6} 3 {s}^{2} 3 {p}^{6} 4 {s}^{1}$.
• Argon's full electronic configuration is $1 {s}^{2} 2 {s}^{2} 2 {p}^{6} 3 {s}^{2} 3 {p}^{6}$.

Most elements tend to want to either gain or lose electrons to become isoelectronic to—or have the same electron configuration as—noble gases.

For most elements, this configuration is $n {s}^{2} n {p}^{6}$ for their valence energy level.

As such, potassium would like to lose its $1$ electron in the $4 s$ orbital for its valence energy level to be $3 {s}^{2} 3 {p}^{6}$ (which is $n {s}^{2} n {p}^{6}$) and become isoelectronic to a noble gas, argon.

As for argon, it already has a $n {s}^{2} n {p}^{6}$ valence shell configuration.
It's a noble gas, so it doesn't want to gain or lose more electrons.