Silicon

On the periodic table, silicon lies on the borderline between the metals and nonmetals. Silicon is essentially a semi-metal (i.e., has some metallic properties such as metallic conductivity) that allows it to be used in semi-conductor devices (i.e., silicon is a semiconductor). Thin slices of ultra-pure silicon crystals, generally known as chips, can have as many as half a million microscopic, interconnected electronic circuits etched into them. These circuits can act as electron gates and perform incredibly complex manipulations of voltages, that can be treated as binary numbers (e.g., voltage on = 1, voltage off = 0).

Silica gel is a porous form of silica, SiO₂, that absorbs water vapor from the air. In its most common form, silica gel is manufactured for use as a drying agent and small packages of silica gel are often packed with shipped products such as electronics that may be sensitive to moisture. Absorption by silica acts to maintain the humidity levels in a package as the package undergoes temperature changes.

Silicon carbide (SiC), is an extremely hard crystalline material, manufactured by fusing sand (SiO₂) with coke (C) in an electric furnace at a temperature above 3,992°F (2,200°C). Silicon carbide, also known by its trade name, Carborundum, is often used as an abrasive, By attaching an ultrasonic impact grinder to a magnetostrictive transducer and using an abrasive liquid containing silicon carbide, holes of practically any shape can be drilled in hard, brittle materials such as tungsten carbide or precious stones.

Silicon based semiconductors are also used in the search for weapons of mass destruction, especially nuclear materials. The interactions of radiation with semi-conducting crystals such as silicon can also be measured and semiconducting radiation detectors have the advantages of small size, high sensitivity, and high accuracy. Silicon chips also are key components of hand-held advanced nucleic acid analyzers (HANAA) that allow real-time polymerase chain reaction (PCR) based tests for pathogens (disease-causing organisms) that can be used by potential bioterrorists.

Silicon is also used in chips to which DNA binds during hybridization procedures.