Lithium is a soft, silver-white metal that belongs to the alkali metal group of chemical elements. It is represented by the symbol Li, and it has the atomic number 3. Under standard conditions it is the lightest metal and the least dense solid element. Like all alkali metals, lithium is highly reactive and flammable. For this reason, it is typically stored in mineral oil. Chemist Jöns Jakob Berzelius gave the alkaline material the name “lithion/lithina”, from the Greek word λιθoς (transliterated as lithos, meaning “ stone”), to reflect its discovery in a solid mineral. He named the metal inside the material as “lithium”.