Question

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

Answer 1

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 `1s^(2)2s^(2)2p^(6)3s^(2)3p^(6)4s^1`.
• Argon's full electronic configuration is `1s^(2)2s^(2)2p^(6)3s^(2)3p^(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 `ns^(2)np^6` for their valence energy level.

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

As for argon, it already has a `ns^(2)np^(6)` valence shell configuration.
It's a noble gas, so it doesn't want to gain or lose more electrons.