Question

What is the electronic configuration of potassium ion?

Answer 1

Well, potassium has `Z=19`.......

Explanation:

And `Z` specifies the nuclear charge. For a neutral element there must be 19 electrons, 19 fundamental particles of negative charge. The electrons are arranged into shells....

And so the ion `K^+` must have 18 electrons: `1s^(2)2s^(2)2p^(6)3s^(2)3p^6`, and this configuration is precisely the same as that possessed by argon. Why?