Question

What is the formula of the ion formed when potassium achieves noble-gas electron configuration

Answer 1

potassium is an alkali metal which means that it only needs to get rid of one electron to achieve a noble gas configuration.  Since it only needs to get rid of one electron the ion will be a cation with a charge of +1 which means the symbol will be K⁺.

I hope this helps.  Let me know if anything is unclear.

Answer 2

Answer;

K+

Explanation;

-Noble gas configuration is the electron configuration equivalent to noble gases or group 8 elements. According to the octet rule an atom of an element gains or looses electrons to attain noble gases configuration which is the stable configuration, such that an atom has attained maximum number of electrons in the outermost energy level.

-For instance potassium is an alkali metal, consisting of one valence electron in the outermost energy level. For an atom of potassium to attain octet configuration or noble gases configuration it will have to loose one electron, thus forming a positively charged ion of potassium, K+.