Lithium Lithium Lithium (from ) is a chemical element with symbol Li and atomic number 3. It is a soft, silvery-white alkali metal. Under standard conditions, it is the lightest metal and the lightest solid element. Like all alkali metals, lithium is highly reactive and flammable, and is stored in mineral oil. When cut, it exhibits a metallic luster, but moist air corrodes it quickly to a dull silvery gray, then black tarnish. It never occurs freely in nature, but only in (usually ionic) compounds, such as pegmatitic minerals which were once the main source of lithium. Due to its solubility
Metallic hydrogen metallic hydrogen in the laboratory has been described as "...the holy grail of high-pressure physics." The initial prediction about the amount of pressure needed was eventually shown to be too low. Since the first work by Wigner and Huntington, the more modern theoretical calculations point towards higher but nonetheless potentially accessible metallization pressures of around . Helium-4 is a liquid at normal pressure near absolute zero, a consequence of its high zero-point energy (ZPE). The ZPE of protons in a dense state is also high, and a decline in the ordering energy (relative to the ZPE) is expected at high