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

Answer:

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:

Ptable

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.