Tag Archives: semimetals

Silicon Facts

Silicon is the 14th element of the periodic table. These silicon facts contain chemical and physical data along with general information and history.

Element cell for Silicon

Silicon Periodic Table Cell

Basic Silicon Facts

Name: Silicon

Atomic Number: 14

Element Symbol: Si

Group: 14

Period: 3

Block: p

Element Family: Metalloid or Semi-metal

Atomic Mass: [28.084; 28.086]
IUPAC guidelines to reflect the physical and chemical history of the magnesium sample. If a single value of the atomic mass is needed, use 28.0855.

Electron Configuration: [Ne]3s23p2 (shorthand) or 1s22s22p63s23p(full)

Discovery: Jöns Jacob Berzelius in 1824.

Silicon compounds have been commonplace since ancient times. Flint is a silicon oxide mineral and was the basis for many prehistoric tools. Sand, another silicon compound, was made into glass. French chemist Antoine Lavoisier was the first to write about the possibility of silica containing an unknown element. Several chemists attempted to isolate silicon using electrolysis, but were unsuccessful. Jöns Jacob Berzelius managed to isolate silicon using chemical processes in 1824.

Name Origin: Sir Humphry Davy suggested the name slicium in 1808 for after the Latin word silex meaning flint. He believed silicon was a metal and added the -ium suffix. In 1817, Scottish chemist Thomas Thomson discovered silicon was not a metal, but more like boron. He changed Davy’s name by swapping the suffix to -on.

Isotopes:

Natural silicon is comprised of three stable isotopes: 28Si, 29Si and 30Si. Trace amounts of 28Si exits when cosmic rays react with atmospheric argon. Twenty radioactive isotopes have been produced under laboratory conditions ranging from 22Si to 45Si.

28Si
Silicon-28 is a stable isotope containing 14 neutrons. 92.223% of natural silicon is silicon-28.

29Si
Silicon-29 is a stable isotope containing 15 neutrons. 4.685% of natural silicon is silicon-29.

30Si
Silicon-30 is a stable isotope containing 16 neutrons. 3.092% of natural silicon is silicon-30.

32Si
Silicon-32 is a radioactive isotope containing 18 neutrons. Silicon-32 is formed as a daughter particle from the reaction between cosmic radiation and atmospheric argon. It decays further by β- decay into 32P with a half-life of 15,319 years.


Silicon

Silicon (Enricoros/Creative Commons)

Physical Data

Density: 2.3296 g/cm3

Melting Point: 1687 K ​(1414 °C, ​2577 °F)

Boiling Point: 3538 K ​(3265 °C, ​5909 °F)

State at 20ºC: Solid

Heat of Fusion: 50.21 kJ/mol

Heat of Vaporization: 383 kJ/mol

Molar Heat Capacity: 19.789 J/mol·K


Silicon Atom

Electron shell configuration of a silicon atom.

Atomic Data

Atomic Radius: 1.11 Å (empirical)

Covalent Radius: 1.11 Å

Van der Waals Radius:  2.10 Å

Electron Affinity: 134.068 kJ/mol

Electronegativity: 1.90

1st Ionization Energy: 786.518 kJ/mol

2nd Ionization Energy: 1577.134 kJ/mol

3rd Ionization Energy: 3231.585 kJ/mol

4th Ionization Energy: 4355.523 kJ/mol

5th Ionization Energy: 16090.571 kJ/mol

6th Ionization Energy: 19805.55 kJ/mol

7th Ionization Energy: 23783.6 kJ/mol

8th Ionization Energy: 29287.16 kJ/mol

Oxidation States: +4, -4 (common), +3, +2, +1, -1, -2, -3 (uncommon)


Avogadro Project Silicon Sphere

Achim Leistner holding a sphere of ultrapure silicon monocrystal for the Avogadro Project. Credit: Australian Centre for Precision Optics (ACPO)/Commonwealth Scientific and Industrial Research Organization (CSIRO)

Fun Silicon Facts

  • Silicon is a bluish-gray shiny solid at room temperature.
  • Silicates (silicon oxide) are the most common minerals found in the Earth’s crust. This makes silicon is the 2nd most abundant element in the crust.
  • Silicon is the eighth most abundant element in the universe.
  • Silicon is not found free in nature. It is most often found in its oxide form, silicates. Examples include quartz and sand, along with the gemstones amethyst, agate, jaspar, opal and citrine.
  • Silicon is used mostly for glass, ceramics and cement.
  • Silicon is a vital component of semiconductors. Nearly every electronic circuit contains silicon based semiconducting material.
  • The Avogadro Project is a project to produce a standard kilogram mass using a single silicon crystal. These spheres are considered the roundest man-made objects ever created.
  • Silicon is refined commercially by heating sand and carbon in an electric furnace. Ultrapure silicon is extracted using a molten salt electrolysis technique.
  • Silicones (silicon-oxygen-hydrocarbon compounds) range from liquids to hard solids and have many useful properties, including use as adhesives, sealants, lubricants and insulators.
  • Diatom creatures absorb silicon from water and incorporate it into their cell walls.
  • Meteorites containing silicon are known as aerolites.

Learn more about elements on the periodic table.

List of Metalloids or Semimetals

The metalloids or semimetals are a group of elements that contain properties of both metals and nonmetals. The highlighted elements are the metalloids.

The metalloids or semimetals are a group of elements that contain properties of both metals and nonmetals. The highlighted elements are the metalloids.

Metalloids, also known as semimetals are elements containing properties similar and midway between metals and nonmetals. They are found to divide the periodic table between the metals on the left and the nonmetals on the right.

Metalloids often have the following properties:

  • could be dull or shiny
  • conducts heat and electricity, but not as well as metals
  • good semiconductors
  • usually malleable
  • usually ductile
  • can both gain and lose electrons in reactions

This is a list of the seven metalloid elements in order of increasing atomic number.

 NUMBER SYMBOLELEMENT
5BBoron
14SiSilicon
32GeGermanium
33AsArsenic
51SbAntimony
52TeTellurium
84PoPolonium

Metals, Metalloids and Nonmetals

The elements of the periodic table can be broken into three different groups: metals, metalloids (or semi-metals) and nonmetals.

Periodic Table Metals Nonmetals and MetalloidsThis periodic table shows the three different groups of elements. The metalloid group separates the metals from the nonmetals. Elements to the left are metals and nonmetals are to the right. The exception is the element hydrogen. Hydrogen has properties of a nonmetal at normal temperatures and pressures.

Properties of Metals

  • solid at room temperature (with the exception of mercury)
  • usually shiny
  • high melting point
  • good conductor of heat
  • good conductor of electricity
  • malleable – able to be pounded into sheets
  • ductile – can be pulled into wire
  • high density (exceptions: lithium, potassium and sodium)
  • corrodes in air or seawater
  • loses electrons in reactions

Properties of Metalloids or Semimetals

  • could be dull or shiny
  • conducts heat and electricity, but not as well as metals
  • good semiconductors
  • usually malleable
  • usually ductile
  • can both gain and lose electrons in reactions

Properties of Nonmetals

  • dull, not shiny
  • poor conductor of heat
  • poor conductor of electricity
  • not malleable or ductile, usually brittle
  • lower density (when compared to metals)
  • lower melting point and boiling points (when compared to metals)
  • gains electrons in reactions