Final answer:
The electron configuration of K (potassium) is 1s²2s²2p⁶4s¹, or in abbreviated form, [Ar]4s¹.
Step-by-step explanation:
The electron configuration of Li is 1s²2s¹, indicating that lithium has two electrons in the 1s subshell and one in the 2s subshell. The configuration of Na is 1s²2s²2p⁶3s¹, which means that sodium has the same inner-shell electrons as neon (Ne), the preceding noble gas, plus one additional electron in the 3s subshell. Following the same trend for the alkali metals, the electron configuration of K (potassium) will include the electron configuration of the preceding noble gas, argon (Ar), plus one additional electron in the 4s subshell. Therefore, the electron configuration of K is 1s²2s²2p⁶4s¹ or using the noble gas shorthand notation, [Ar]4s¹.