|
General |
Name, Symbol, Number | Silicon, Si, 14 |
Series | metalloid |
Group, Period, Block | 14 (IVA)[?], 3, p |
Density, Hardness | 2330 kg/m3, 6.5 |
Appearance | dark grey, bluish tinge |
Atomic Properties |
Atomic weight | 28.0855 amu |
Atomic radius (calc.) | 110 (111)pm |
Covalent radius | 111 pm |
van der Waals radius | 210 pm |
Electron configuration | [Ne]3s2 3p2 |
e- 's per energy level | 2, 8, 4 |
Oxidation states (Oxide) | 4 (amphoteric) |
Crystal structure | Cubic face centered |
Physical Properties |
State of matter | solid (nonmagnetic) |
Melting point | 1687 K (2577 °F) |
Boiling point | 3173 K (5252 °F) |
Molar volume | 12.06 ×10-3 m3/mol |
Heat of vaporization | 384.22 kJ/mol |
Heat of fusion | 50.55 kJ/mol |
Vapor pressure | 4.77 Pa at 1683 K |
Speed of sound | __ m/s at __ K |
Miscellaneous |
Electronegativity | 1.90 (Pauling scale) |
Specific heat capacity | 700 J/(kg*K) |
Electrical conductivity | 2.52 10-4/m ohm |
Thermal conductivity | 148 W/(m*K) |
1st ionization potential | 786.5 kJ/mol |
2nd ionization potential | 1577.1 kJ/mol |
3rd ionization potential | 3231.6 kJ/mol |
4th ionization potential | 4355.5 kJ/mol |
5th ionization potential | 16091 kJ/mol |
6th ionization potential | 19805 kJ/mol |
7th ionization potential | 23780 kJ/mol |
8th ionization potential | 29287 kJ/mol |
9th ionization potential | 33878 kJ/mol |
10th ionization potential | 38726 kJ/mol |
Most Stable Isotopes |
|
SI units & STP are used except where noted. |
Silicon is a
chemical element in the
periodic table that has the symbol
Si and
atomic number 14. A tetravalent
metalloid, silicon is less reactive than its chemical analog
carbon. It is the second most abundant element in the
Earth's crust, making up 25.7% of it by weight. It occurs in
clay,
feldspar,
granite,
quartz and
sand, mainly in the form of
silicon dioxide (also known as silica) and
silicates (compounds containing silicon, oxygen and metals). Silicon is the principal component of
glass,
semiconductors,
cement,
ceramics and
silicones, the latter a plastic substance often confused with silicon.
In its
crystalline form, silicon has a metallic luster and a grayish color. Even though it is a relatively inert element, silicon still reacts with
halogens and dilute
alkalis, but most
acids, (except for
hydrofluoric acid[?]) do not affect it. Elemental silicon transmits more than 95% of all
wavelengths of infrared light.
Silicon is a very useful element that is vital to many human industries.
Silicon dioxide in the form of
sand and
clay is an important ingredient of
concrete and
brick and is also used to produce
Portland cement. Silicon is a very important element for
plant and
animal life.
Diatoms extract silica from water to build their protective cell walls. Other uses:
Silicon (
Latin silex,
silicis meaning
flint) was first identified by
Antoine Lavoisier in
1787, and was later mistaken by
Humphry Davy in
1800 for a compound. In
1811 Gay Lussac and
Thenard[?] probably prepared impure amorphous silicon through the heating of
potassium with silicon tetrafluoride. In
1824 Berzelius prepared amorphous silicon using approximately the same method of Lussac. Berzelius also purified the product by repeatedly washing it.
Silicon is a principal component of
aerolites[?] which are a class of
meteoroids and also of
tektites[?] which is a natural form of glass.
Measured by weight, silicon makes up 25.7% of the earth's crust and after oxygen is also the second most abundant element. Elemental silicon is not found in nature. It occurrs most often as oxides and as silicates. Sand, amethyst, agate, quartz, rock crystal, flint, jasper, and opal are some of the forms in which the oxide appears. Granite, asbestos, feldspar, clay, hornblende, and mica are a few of the many silicate minerals.
Silicon is commercially prepared by the heating of silica and carbon in an electric furnace by using carbon electrodes. The Czochralski process is often used to make high-purity single silicon crystals for use in solid-state[?]/semiconductor devices.
In 1997, regular grade silicon (99% purity) cost about $ 0.50 per g.
Silicon has nine
isotopes, with
mass numbers[?] from 25-33. Si-28 (the most abundant isotope, at 92.23%), Si-29 (4.67%), and Si-30 (3.1%) are stable; Si-32 is a
radioactive isotope produced by
argon decay. Its
half-life, after much argument, has been determined to be approximately 276 years, and it decays by
beta emission to
P-32 (which has a 14.28 year half-life) and then to
S-32.
A serious lung
disease known as
silicosis[?] often occurred in
miners, stonecutters, and others who were engaged in work where siliceous dust was inhaled in great quantities.
Because Silicon is an important element in semiconductor and high-tech devices, the high-tech region of
Silicon Valley,
California, is named after this element.