Why was it named potassium?

In 1807, Humphry Davy produced the element via electrolysis: in 1809, Ludwig Wilhelm Gilbert proposed the name Kalium for Davy's "potassium". In 1814, the Swedish chemist Berzelius advocated the name kalium for potassium, with the chemical symbol "K". read more

Short answer: Potassium was called Potassium (and Sodium Sodium) by Humphry Davy, who first isolated both; it was then renamed Kalium in Germanic countries because of a previous naming proposal by Klaproth, who was the first to show that potassium carbonate and sodium carbonate were different. read more