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What is Silicon

Silicon (pronunciation SIL-ee-ken [2]), represented by the chemical symbol or formula Si [1], is a semiconductor [20] belonging to the carbon family [23]. It can be of two types, amorphous powder and solid crystalline form. Naturally occurring Si is a mixture of three stable isotopes with mass numbers 28, 29 and 30 [1, 3]. It does not react with air on being heated up to 900oC as a very thin film of silicon dioxide on its surface prevents it from further oxidation and makes it inert to water too. It reacts with nitrogen and oxygen above 1400oC. It also reacts with acids and halogens [5].


Where Is It Found

The metalloid is the second most abundant element of the earth comprising 27.7% of its crust by mass. It is usually found as its oxide and silicates in nature [1]. Silica (silicon dioxide) is mined as sand and lode or vein deposits as the element rarely occurs in the uncombined state [17]. Other examples of its oxides are amethyst, opal, agate, etc. while feldspar, mica, clay are its silicate forms. The element is commercially manufactured in electric furnaces by reducing sand with carbon [1]. Its refining or purification process involves reducing silicon tetrachloride or trichlorosilane [34]. Since it is important to maintain healthy bones and teeth and growing nails, hair and skin on the human body, you can include the mineral in your diet in the form of foods such as raisins, brown rice, green beans, etc [27].

Silicon Image


Origin of Its Name: Its name is derived from the Latin ‘silex’ or ‘silicis’ meaning flint, one of its oxide forms [1].

Who Discovered It: Swedish chemist, Jöns Jacob Berzelius [1, 2].

When and Where Was Silicon Discovered: It was discovered in 1824 in Stockholm, Sweden [1].

How Was It Discovered

Attempts to reduce silica to its constituents having failed, in 1811 French chemists Joseph Gay Lussac and Louis Jacques Thénard performed a chemical reaction of silicon tetrachloride with metallic potassium and obtained silicon in a very impure form. However, the real credit of discovering it goes to Berzelius who produced silicon by heating potassium with potassium fluorosilicate in 1824. He removed the potassium silicide contaminations by stirring the product with water obtaining comparatively pure silicon powder [1].

Silicon Element

Silicon Identification

Atomic Number  14 [1]
CAS Number  7440-21-3 [1]
Position in the periodic table Group Period Block
  14 [1] 3 [1] p [1]

Properties and Characteristics of Silicon

General Properties

Atomic mass 28.085 atomic mass units [1]
Atomic weight 28.085 [1]
Mass number 28 [15]
Molar mass/molecular weight 28.085 g/mol [12]

Physical Properties

Color/appearance Silvery [3]
Luster Blue-gray metallic sheen [1]
Texture Hard [28]
Malleability No [6]
Ductility No [6]
Melting point/freezing point 1414°C, 2577°F [1]
Boiling point 3265°C, 5909°F [1]
Density 2.3296 g cm-3 [1]
State of matter at room temperature (normal phase) Solid [1]
Hardness (Vickers scale) 9630.1303 MPa [9]
Electrical conductivity 1000 S/m [7]
Thermal Conductivity 150 W/(m K) [8]
Dielectric constant/relative permittivity 11.7 [18]
Specific heat capacity 0.7 J g-1oC-1 [18]
Resistivity 6.4 x 102 ohm-m [21]
Young’s modulus 140-180 GPa [26]
Tensile strength 165-180 MPa [26]
Refractive index 3.9766 [38]

Chemical Properties

Flammability Yes [10]
Oxidation states/ionic charge +4, +2, -4 [2]

Atomic Data of Silicon Element

Valence electrons/valency 4 [4]
Quantum numbers
– n 3 [4]
– ℓ 1 [4]
– m 0 [4]
– m s [4]
Electron configuration (noble gas configuration) [Ne] 3s23p2 [1]
Crystal structure Diamond [13]
Lattice constant 5.431 Å [18]
Atomic structure
– Number of Electrons 14 [3]
– Number of Neutrons 14 [3]
– Number of Protons 14 [3]
Energy levels [3]
– First Energy Level 2
– Second Energy Level 8
– Third Energy Level 4
Radius of atom
– Atomic Radius 2.10 Å [1]
– Covalent Radius 1.14 Å [1]
Electronegativity (Pauling scale) 1.90 [1]
Electron affinity 134.068 kJ mol−1 [1]
Ionization energy

(kJmol-1) [1]

1st 2nd 3rd 4th 5th 6th 7th
786.518 1577.134 3231.585 4355.523 16090.571 19805.55 23783.6

Silicon Electron Configuration (Bohr Model)

Silicon Lewis Dot Structure/Electron Dot Diagram

Silicon Uses

  1. In electronic circuits, the semiconductor is used as a conductor by doping it with impurities [11, 20]. Silicon controlled rectifiers are used in switching power in high voltage DC and AC circuits [14]. It is also used in things used in everyday life such as, transistors, diodes (including photodiodes), microchips, optical modulators, dies, wafers, batteries, computer chips, hybrid silicon lasers, and silicon photomultiplier, a radiation detector [17, 22, 32].
  2. Amorphous silicon, its non-crystalline form, is used in solar cells and panels [16].
  3. Most of the rocks and granite are complex silicates used in civil engineering projects [1].
  4. Silicon supplements act as medicines to treat osteoporosis, stroke, heart diseases, hair loss, etc [19].
  5. As fertilizers in agriculture [25].
  6. Sand is used in making construction material and glass [1]. Another oxide quartz is used in making watches [40].
  7. To increase the hardness and strength of steel and in semiconductor packaging technology [31, 39].
  8. Silicon nanowires find application in photonic devices [33]. Silicon optical fibers are more energy efficient than the standard ones [35].
  9. The silicon on insulator fabrication process makes a switch operate faster [37].

Picture of Silicon

Is It Dangerous

The element is essential to plant life, but its application in animal cells is doubtful. Though it is itself not poisonous or hazardous, some silicates like asbestos are carcinogenic. Stonecutters, miners and other workers exposed to siliceous dust are likely to develop a serious lung disease known as silicosis [1].

Things Made from Silicon

Interesting Facts

  • Silicon crystal graphite batteries are an excellent eco-friendly, more efficient and cheaper alternative to standard lithium-ion batteries [24].
  • Si crystal is anisotropic meaning it exhibits different properties in different directions with respect to the crystal orientation. This makes it an excellent engineering material [29].
  • An innovative idea of lithium-ion batteries with their anodes replaced by silicon coating or nanotubes for extended lives is undergoing testing [30].
  • Silicon could help promote renewable energy generation according to latest research [36].

What Does Silicon Look Like

Silicon (Si Element) Cost

The pure element is priced at $5.4 for every 100 gram and in bulk, it costs $0.14 for the same quantity [3].



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