Lithium is a chemical element with the symbol Li and atomic number 3. It is a soft, silvery-white alkali metal that belongs to the group of elements known as the alkali metals. Lithium is the lightest metal and the least dense solid element. It is highly reactive and flammable and must be stored in mineral oil.
Lithium has a number of important uses. One of its most well-known applications is in rechargeable lithium-ion batteries, which are used to power a wide range of devices including smartphones, laptops, and electric vehicles.