Period 2 element two make up all natural occurrence of lithium on Earth, although further isotopes have been synthesized. In ionic compounds, lithium loses an electron to become positively charged, forming the cation Li. Lithium is the first alkali metal in the periodic table, and the first metal of any kind in the periodic table. At standard temperature and pressure, lithium is a soft, silver-white, highly reactive metal. With a density of 0.564 g·cm, lithium is the lightest metal and the least dense solid element. Lithium is one of the few elements synthesized in the Big Bang, making it a primordial element. Lithium
Solid hydrogen Phase IV is (or is similar to) a structure of "Pc" symmetry, consisting of alternate layers of strongly bonded molecules and weakly bonded graphene-like sheets. Solid hydrogen Solid hydrogen is the solid state of the element hydrogen, achieved by decreasing the temperature below hydrogen's melting point of . It was collected for the first time by James Dewar in 1899 and published with the title "Sur la solidification de l'hydrogène" (English: On the solidification of hydrogen) in the "Annales de Chimie et de Physique", 7th series, vol. 18, Oct. 1899. Solid hydrogen has a density of 0.086 g/cm making it