Nonmetal as nonmetals. Among the reactive nonmetals, carbon, phosphorus, selenium, and iodine—which border the metalloids—show some metallic character, as does hydrogen. Among the noble gases, radon is the most metallic and begins to show some cationic behaviour, which is unusual for a nonmetal. The seven metalloids are boron (B), silicon (Si), germanium (Ge), arsenic (As), antimony (Sb), tellurium (Te), and astatine (At). On a standard periodic table, they occupy a diagonal area in the p-block extending from boron at the upper left to astatine at lower right, along the dividing line between metals and nonmetals shown on some periodic tables. They
Germanium defense stockpile in 1987. Germanium differs from silicon in that the supply is limited by the availability of exploitable sources, while the supply of silicon is limited only by production capacity since silicon comes from ordinary sand and quartz. While silicon could be bought in 1998 for less than $10 per kg, the price of germanium was almost $800 per kg. Under standard conditions, germanium is a brittle, silvery-white, semi-metallic element. This form constitutes an allotrope known as "α-germanium", which has a metallic luster and a diamond cubic crystal structure, the same as diamond. At pressures above 120 kbar, it