Periodic Table

Silicon

Metalloid

Quick Facts about Silicon

Al
  • solid- state of matter at room temperature
  • Stable- has at least one stable isotope
  • +4, +2, -4- common oxidation states in compounds
  • DIA- crystal structure, atomic arrangement in solid form
P

Silicon (Si) is element 14 on the periodic table. Atomic mass of Si: 28.0850 u. Si is in period 3, group 14. Melting point of Si: 1687.00 K.Density of Si: 2.33 g/cm³.

Why Silicon Matters

The element that makes computer chips and beach sand

In Your Home

  • Computer chips and electronics
  • Glass windows and mirrors
  • Silicone sealants and bakeware
  • Solar panels on rooftops

Industry Uses

ElectronicsSemiconductors in all computer chips and processors
SolarPhotovoltaic cells for solar panels
ConstructionGlass, concrete, ceramics
ChemicalSilicones for sealants, lubricants, medical implants

In Your Body

✗ Not essential

Possibly essential in trace amounts for bone and connective tissue. Abundant in plants (gives bamboo strength). Silica in diatoms and sponges.

Safety: Elemental silicon is non-toxic. Crystalline silica dust causes silicosis (lung disease). Silicones are generally biocompatible.

Discovery of Silicon

Discovered by Jöns Berzelius in Sweden, 1824

Name origin: Latin: silex, silicus, (flint).

History & Events

1824
Isolation
Jöns Jacob Berzelius isolated amorphous silicon by heating potassium fluorosilicate
1954
Silicon Transistor
Texas Instruments produced first silicon transistor, beginning the silicon age
1971
Intel 4004
Intel released first commercial microprocessor, starting the PC revolution

About Silicon

Metalloid element belonging to group 14 of the periodic table. It is the second most abundant element in the Earth's crust, making up 25.7% of it by weight. Chemically less reactive than carbon. First identified by Lavoisier in 1787 and first isolated in 1823 by Berzelius.

Atomic Properties of Si

Atomic Number of Si
14
Atomic Mass of Si
28.0850 u
Electron Configuration
[Ne] 3s2 3p2
Electronegativity
1.90
Block
p-block
Group
14
Period
3

Physical Properties of Si

Phase (STP)
solid
Melting Point of Si
1687.00 K
Boiling Point of Si
3538.00 K
Density of Si
2.3290 g/cm3

Thermal Properties

Heat of Fusion
50.60 kJ/mol
Heat of Vaporization
383.00 kJ/mol
Specific Heat
0.71 J/g·K
Molar Heat Capacity
19.99 J/mol·K
Thermal Conductivity
149.00 W/m·K

Atomic Radii

Calculated
110 pm
Covalent
116 pm
Van der Waals
210 pm
Metallic
117 pm

Common Misconceptions

Wrong:Silicon and silicone are the same.
Correct:Silicon is an element (Si). Silicone is a synthetic polymer containing silicon, oxygen, carbon, and hydrogen.
Wrong:Silicon Valley is named for sand.
Correct:It's named for silicon in computer chips made there, not the sand that contains silicon dioxide.
Wrong:Silicon is rare.
Correct:Silicon is the second most abundant element in Earth's crust (28%)—only oxygen is more common.

Isotopes of Silicon

Silicon has 3 naturally occurring isotopes, plus 1 notable radioactive isotope.

IsotopeAtomic Mass (u)AbundanceHalf-LifeDecay Mode
2814Si (Si-28)Silicon-28 isotope27.9769265392.22%——
2914Si (Si-29)Silicon-29 isotope28.976494664.685%——
3014Si (Si-30)Silicon-30 isotope29.973770143.092%——
3214Si (Si-32)Silicon-32 isotope31.97414840%153 yearsβ⁻

Data source: NIH PubChem (aggregated from IUPAC, NIST)

Isotope Applications

Isotopes of Silicon have important real-world applications in science and industry.

Geochronology & Dating

Cosmogenic 32Si has a half-life of about 150 years and is produced by cosmic-ray spallation of argon in the stratosphere and troposphere [124]. 32Si in dust is precipitated in snow, making it possible to date dust in snow and glacial ice (Fig. IUPAC.14.2). Glaciers are archives for global climate history because they contain a variety of proxies (imprints of past environmental conditions used to interpret paleoclimate) for climate forcing and climate response. Cosmogenic 32Si that is stored in glaciers and ice-core samples can be analyzed using accelerator mass spectrometry to date when sections of glaciers formed [125], [126].

Industrial Applications

At Keio University in Japan, the Itoh Research Group has developed a method that utilizes 29Si to store and process information. The Itoh Research Group focused on manipulating the nanostructure of materials at an atomic level, especially with semiconductors such as silicon. Their manipulations and observations demonstrate that differences in the nuclear spin and mass of an isotope affects the ease of further manipulation of the isotope [128], [129]. Silicon crystals enriched to higher than 99.99 percent purity of 28Si are being used in the Avogadro Project. This project is intended to remeasure the Avogadro constant (NA), which is the proportionality factor between the amount of substance and number of elementary entities [130].

Abundance

Earth's Crust
282.0 g/kg
Seawater
2.2 mg/L

Uses

Used in glass as silicon dioxide (SiO2). Silicon carbide (SiC) is one of the hardest substances known and used in polishing. Also the crystalline form is used in semiconductors.

Sources

Makes up major portion of clay, granite, quartz (SiO2), and sand. Commercial production depends on a reaction between sand (SiO2) and carbon at a temperature of around 2200 °C.

Geochemistry

Goldschmidt
litophile
Geochemical Class
major

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