Nonmetal Silicon

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Nonmetal Silicon The second most abundant element on Earth is the nonmetal

silicon, which makes up about 28 percent of the Earth's crust. It

occurs only in such combined forms as silica (silicon dioxide) and

silicate rocks and minerals. The most common form of silica is quartz,

which includes sand and flint. Silicates are salts in which silica is

combined with oxygen and other elements, such as aluminum, magnesium,

calcium, sodium, iron, and potassium.

Silicon has a strong affinity for oxygen. Pure silicon can be obtained

by breaking down its combined form. It is prepared commercially by

reducing (removing the oxygen from) the oxide by reaction with a

carbon-based substance such as coke in electric furnaces. Some silicon

is obtained by reducing silicon dioxide with aluminum. Amorphous

silicon, prepared in the laboratory by heating silica with magnesium

powder, is a dark-brown crystalline powder.

Pure silicon is a hard, dark-gray solid with a metallic luster. Its

crystalline structure is the same as that of the diamond form of

carbon, with which silicon shares many chemical and physical

properties. Elemental silicon has few applications; it is used in

metallurgy as a reducing agent and as an alloying element in steel,

brass, and bronze. (See also Alloy.)

Highly purified silicon is a poor conductor of electricity. When it is

doped, or treated with other atoms, however, it yields electrons for a

current. The silicon that is produced in this process is used

extensively in transistors, integrated circuits, photoelectric

devices, and othe...

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...20? C) 5.75-7.31

Boiling Point 4,118? F (2,270? C)

Melting Point 450? F (232? C)

Germanium, brittle silver element predicted in 1871 by Mendeleev but

not discovered until 1886 by Clemens Winkler. It is used as

superconductor in electronics; window and lens component in equipment

to measure infrared radiation; component of camera lenses and

microscopes; and in transistors and in phosphors for fluorescent

lamps. It is found as a part of the minerals argyrodite, germanite,

and renierite and in coal. It can kill certain harmful bacteria

without causing toxicity to humans and is being studied as a

therapeutic agent.

Properties of Germanium

Symbol Ge Atomic number 32 Atomic weight 72.59 Group in periodic table

IVa Boiling point 4,892o F (2,700o C) Melting point 1,719o F (937.2o

C) Specific gravity 5.323

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