Silicon °C respectively are the second-highest among all the metalloids and nonmetals, being only surpassed by boron. Silicon is the eighth most common element in the universe by mass, but very rarely occurs as the pure element in the Earth's crust. It is most widely distributed in dusts, sands, planetoids, and planets as various forms of silicon dioxide (silica) or silicates. More than 90% of the Earth's crust is composed of silicate minerals, making silicon the second most abundant element in the Earth's crust (about 28% by mass) after oxygen. Most silicon is used commercially without being separated, and often with
Binary compounds of silicon practical applications), formed by annealing an amorphous Si-P alloy. The arsenic–silicon phase diagram measured at 40 Bar has two phases: SiAs and SiAs. The antimony–silicon system comprises a single eutectic close to the melting point of Sb. The bismuth system is a monotectic. In group 16 silicon dioxide is a very common compound that widely occurs as sand or quartz. SiO is tetrahedral with each silicon atom surrounded by 4 oxygen atoms. Numerous crystalline forms exist with the tetrahedra linked to form a polymeric chain. Examples are tridymite and cristobalite. A less common oxide is silicon monoxide that can be