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
Standard molar entropy all gases. Under identical conditions, it is greater for heavier gas. Standard molar entropy In chemistry, the standard molar entropy is the entropy content of one mole of substance under a standard state (not STP). The standard molar entropy is usually given the symbol "S"°, and has units of joules per mole kelvin (J mol K). Unlike standard enthalpies of formation, the value of "S"° is absolute. That is, an element in its standard state has a definite, nonzero value of "S" at room temperature. The entropy of a pure crystalline structure can be 0 J mol K only at