Question

identify whether longhand notation or noble - gas notation was used in each case below. potassium (k): 1s²2s²2p⁶3s²3p⁶4s¹ longhand notation noble - gas notation complete iron (fe): ar4s²3d⁶ longhand notation noble - gas notation done

Explanation:

Longhand notation lists all electron - occupied orbitals starting from 1s. Noble - gas notation uses the symbol of the nearest noble gas with a completed electron shell in brackets and then lists the remaining electrons. For potassium, all orbitals are listed out, so it's longhand. For iron, [Ar] represents the electron configuration of argon (a noble gas) and then the remaining electrons are listed, so it's noble - gas notation.

Answer:

Potassium (K): longhand notation
Iron (Fe): noble - gas notation