Silicon Dioxide (SiO2) Properties (25 Facts You Should Know)

Silicon dioxide is an inorganic compound that is also known as the constituent of sand in nature. Let us discuss the properties of silicon dioxide.

Silicon dioxide has a dean crystalline structure with a Si–O bond length of 161 pm. The most stable form is alpha quartz at room temperature and the transformation takes place at 573 °C. Quartz comprises more than 10% of the mass of the earth’s crust.

In this article, we will discuss the melting point, boiling point, viscosity, color, and molar mass with detailed explanations.

Silicon dioxide IUPAC name

The IUPAC name (international union of pure and applied chemistry) of silicon dioxide is silicon dioxide itself.

Silicon dioxide chemical formula

Silicon dioxide has the chemical formula SiO2. In this formula, silicon is the central atom and it is attached to two atoms of oxygen it is attached with double bonds with the central atom silica and it is hard and the most abundant mineral on the earth.

Silicon dioxide CAS number

Silicon dioxide has a CAS registry number authentic numeric identifier which contains up to 10 digits 7631-86-9

Silicon dioxide ChemSpider ID

Silicon dioxide has the ChemSpider ID is a free chemical structure database 22683

Silicon dioxide chemical classification

  • Silicon dioxide can be chemically classified as silica.
  • Silicon dioxide is most commonly found in nature as quartz and found in minerals like sand and as it is crystalline in structure they are not easily soluble in water as it is soluble at 340 °C.
  • SiO2 has two types of quartz alpha and beta.

Silicon dioxide molar mass

The mass of one mole of silicon dioxide is 60.08 g/mol.

Silicon dioxide color

Pure silicon dioxide is white and is in white powdered form which is found in the earth’s crust in the crystalline form obtained from mines and by purifying the quartz.

Silicon dioxide viscosity

Silicon dioxide has a viscosity of 1.6 cP (centipoises) it is less because of the crystalline nature of silica and it also needs a very high temperature to be soluble in water as compared to quartz as it needs a temperature of about 340°C.

Silicon dioxide molar density

The molar density of silicon dioxide is 60.0843 m/cm3 because it has a density of 2.648 g/cm3.

Silicon dioxide melting point

Silicon dioxide has a melting point of 1,600°C. or 2,912 F. The melting point of silicon dioxide is this high because of the double bond present between the oxygen and silicon atom as more energy is required to break the bonds.

Silicon dioxide boiling point

The boiling point of silicon dioxide is 4,046°F or 2,230 °C. The boiling point of silicon dioxide is this much high because of its big covalent structure a large amount of energy is needed to break the bonds between silicon and oxygen and the double bond is also one reason.

Silicon dioxide state at room temperature

Silicon dioxide is solid at room temperature or crystalline solid may be in powder form as it is the large constituent mineral of the sand and alpha quartz is the most stable form of silicon dioxide and crystalline solid at room temperature.

Silicon dioxide covalent bond

There are a total of two covalent bonds present in silicon dioxide. Two double bonds are present between the silicon atom and oxygen atom a linear structure according to the geometry of the atoms.

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Covalent bond in silicon dioxide

Silicon dioxide covalent radius

The covalent radius of silicon dioxide is 1.11 Angstroms.

Silicon dioxide electron configurations

The electronic configuration is the division of the electrons in the atomic orbital or shells which are s, p, d, and f orbital. Let us explain the electronic configuration of silicon dioxide.

The electronic configuration of silicon is 1s2 2s2 2p6 3s2 3p2and oxygen is 1s2 2s2 2p4 for SiO2.

Silicon dioxide oxidation state

The central atom of silicon is in a 0 oxidation state in silicon dioxide but the oxidation state of the whole element will be +4 because there are two atoms of oxygen attached to the central atom which is silicon.

Silicon dioxide acidity/alkaline

Silicon dioxide is not acidic or alkaline because of the absence of hydrogen atoms and due to this absence of hydrogen, they are not soluble in water as it cannot form any bond with water.

Is silicon dioxide odourless

 silicon dioxide is an odourless compound or odourless crystalline amorphous solids that do not produce any odour even on heating too.

Is silicon dioxide paramagnetic

If there are paired electrons then it is paramagnetic. Let us if the silicon dioxide is magnetic or not.

Silicon dioxide is diamagnetic due to the presence of paired electrons in the outermost shell of silicon and oxygen they are not paramagnetic.

Silicon dioxide hydrates

  • Silicon dioxide forms hydrates in the form of hydrated silica and it is said to be silicic acid when gets dissolved in water .
  • Silicon dioxide found in some gemstones like opal and the cell walls of seaside animals like diatoms.

Silicon dioxide crystal structure

Solid silicon dioxide structure tetrahedral crystalline structure or diamond-like crystalline structure. In Alpha quartz, the length of the Si–O bond is 161 pm, and in α-tridymite, it is from 154 to 171 pm.         

Silicon dioxide polarity and conductivity

  • Silicon dioxide is a partially polar compound due to the presence of oxygen and it is a bad conductor of electricity.
  • Silicon dioxide can work as a semiconductor after adding some metals to it so we can say that it is a good semiconductor.

Silicon dioxide reaction with acid

Silicon dioxide reacts with HF6 which is hydrofluoric acid and produces hexaflourosilicic acid.

SiO2 + HF6 —–> 6FSiO

Silicon dioxide reaction with base

Silicon dioxide reacts with dinitrogen and with ethylene glycol with an alkali metal base to produce pentacoordinate silicates which produce a wide range of new silicon compounds.

SiO2 + 2N2 +CH2-OH —–>5SiO2

Silicon dioxide reaction with oxide

The dimeric silicon dioxide is obtained by a reaction of oxygen with matrix-isolated dimeric silicon monoxide, in this, there are two oxygen atoms between the silicon.

2SiO2 + O2 ——-> 4SiO2

Silicon dioxide reaction with metal

Silicon dioxide reactions rarely react with metals because the central atom is completely satisfied with the valency.


Silicon dioxide has a different use in various fields. Most of the silicon dioxide is used in the building industry and the cement industry and for making glasses also use as an anti-clacking agent to avoid clumps and also use in the food industry or powdered food and beverages.