Silicon
Silicon General
Name:Silicon | Symbol:Si |
Type:Non-Metal, Carbon group | Atomic weight:28.0855 |
Density @ 293 K:2.33 g/cm3 | Atomic volume:12.1 cm3/mol |
Discovered:
In 1789, the French chemist Antoine Lavoisier proposed that quartz (crystalline silicon dioxide) was likely to be the oxide of an element which was very common but not yet identified or isolated. (1) |
Silicon States
State (s, l, g):solid | |
Melting point:1687 K (1414 °C) | Boiling point:3538 K (3265 °C) |
Silicon Energies
Specific heat capacity:0.71 J g-1 K-1 | Heat of atomization:456 kJ mol-1 |
Heat of fusion:50.21 kJ mol-1 | Heat of vaporization :359 kJ mol-1 |
1st ionization energy:786.4 kJ mol-1 | 2nd ionization energy:1577 kJ mol-1 |
3rd ionization energy:3231.4 kJ mol-1 | Electron affinity:133.6 kJ mol-1 |
Silicon Oxidation & Electrons
Shells:2,8,4 | Electron configuration:[Ne] 3s2 3p2 |
Minimum oxidation number: -4 | Maximum oxidation number:4 |
Min. common oxidation no.: -4 | Max. common oxidation no.:4 |
Electronegativity (Pauling Scale):1.9 | Polarizability volume:5.4 Å3 |
Silicon Appearance & Characteristics
Structure:diamond structure | Color: brown (amorphous), gray-black (crystalline) |
Hardness:7 mohs | |
Harmful effects:
Silicon is not known to be toxic, but if breathed in as a fine silica/silicate dust it may cause chronic respiratory problems. Silicates such as asbestos are carcinogenic. |
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Characteristics:
Silicon is a hard, relatively inert metalloid and in crystalline form is very brittle with a marked metallic luster. Silicon occurs mainly in nature as the oxide and as silicates. The solid form of silicon does not react with oxygen, water and most acids. Silicon reacts with halogens or dilute alkalis. Silicon also has the unusual property that (like water) it expands as it freezes. Four other elements expand when they freeze; gallium, bismuth, antimony and germanium Uses: Silicon chips are the basis of modern electronic and computing. The silicon must be ultrapure, although depending on final use it may be doped with part per million levels of arsenic, boron, gallium, germanium, or phosphorus. |
Silicon Reactions
Reaction with air:none | Reaction with 6 M HCl:none |
Reaction with 15 M HNO3:none | Reaction with 6 M NaOH:mild, ⇒ silicates |
Silicon Compounds
Oxide(s):SiO2 | Chloride(s):SiCl4, Si2Cl6 + more |
Hydride(s):SiH4 (silane), Si2H6 + more |
Silicon Radius
Atomic radius:110 pm | Ionic radius (1+ ion):pm |
Ionic radius (2+ ion):pm | Ionic radius (3+ ion):pm |
Ionic radius (2- ion):pm | Ionic radius (1- ion):pm |
Silicon Conductivity
Thermal conductivity:149 W m-1 K-1 | Electrical conductivity:1.2 x 10-5 S cm-1 |
Silicon Abundance & Isotopes
Abundance earth's crust: 28 % by weight, 21 % ppm by moles | |
Abundance solar system:900 parts per million by weight, 40 parts per million by moles | |
Cost, pure: $5.4 per 100g | |
Cost, bulk: $0.14 per 100g | |
Source:
Silicon is the second most abundant element in Earth's crust, after oxygen and the eighth most abundant in the Universe. It is most commonly found as silicon dioxide (silica). Two elements, silicon and oxygen, make up almost three-quarters of our planet's crust. Commercial quantities of silicon are obtained by the reaction of silicon dioxide and carbon in an electric furnace using carbon electrod |
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Isotopes:
Silicon has 14 isotopes whose half-lives are known, with mass numbers 22 to 36. Of these, three are stable: 28Si, 29Si and 30Si. |
Silicon Other
Other:
References |
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