Silicon (Si)

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 Number	14
Atomic Weight	28.085
Mass Number	28

Group	14
Period	3
Block	p

Protons	14 p⁺
Neutrons	14 n⁰
Electrons	14 e^-

Properties

Energy
Atomic Radius	110 pm 232 pm
Molar Volume	12.1 cm³/mol
Covalent Radius	116 pm 107 pm 102 pm 117 pm 111 pm
Metallic Radius	117 pm 138 pm
Ionic Radius	26 pm 40 pm
Crystal Radius	40 pm 54 pm
Van der Waals Radius	210 pm 210 pm 427 pm 210 pm 229 pm 429.5 pm
Density	2.3296 g/cm³ 2,570 kg/m³
Proton Affinity	837 kJ/mol
Electron Affinity	1.3895211 eV/particle
Ionization Energy	8.151683 eV/particle 16.345845 eV/particle 33.493 eV/particle 45.14179 eV/particle 166.767 eV/particle 205.267 eV/particle 246.32 eV/particle 303.66 eV/particle 351.1 eV/particle 401.38 eV/particle 476.18 eV/particle 523.415 eV/particle 2,437.65804 eV/particle 2,673.1774 eV/particle
Heat of Vaporization	383 kJ/mol
Heat of Fusion	50.6 kJ/mol
Heat of Formation	450 kJ/mol
Electrons
Electron Shells	2, 8, 4
Valence Electrons	4
Electron Configuration	[Ne] 3s² 3p²
Oxidation States	-4, -3, -2, -1, 0, 1, 2, 3, 4
Electronegativity	11.33 eV/particle 0.178503 1.9
Electrophilicity	1.6827934805482991 eV/particle
Phases
Phase	Solid
Gas Phase
Boiling Point	3,538.15 K
Melting Point	1,687.15 K
Critical Pressure
Critical Temperature
Triple Point
Visual
Color	Gray #daa520 #f0c8a0 #f0c8a0
Appearance	crystalline, reflective with bluish-tinged faces
Refractive Index
Thermodynamic Properties
Thermal Conductivity	149 W/(m K)
Thermal Expansion	0.0000026 1/K
Molar Heat Capacity	19.99 J/(mol K)
Specific Heat Capacity	0.712 J/(g⋅K)
Heat Capacity Ratio (Adiabatic Index)
Electrical Properties
Type	Semiconductor
Electrical Conductivity	0.001 MS/m
Electrical Resistivity	0.001 m Ω
Superconducting Point
Magnetism
Type	diamagnetic
Magnetic Susceptibility (Mass)	-0.0000000016 m³/Kg
Magnetic Susceptibility (Molar)	-0.0000000000449 m³/mol
Magnetic Susceptibility (Volume)	-0.00000373
Magnetic Ordering
Curie Point
Neel Point
Structure
Crystal Structure	Tetrahedral Packing (DIA)
Lattice Constant	5.43 Å
Lattice Angles	π/2, π/2, π/2
Mechanical Properties
Hardness	6.5 MPa
Bulk Modulus	100 GPa
Shear Modulus
Young Modulus	47 GPa
Poisson Ratio
Speed of Sound	2,200 m/s
Classification
Category	Metalloids, Metalloids
CAS Group	IVB
IUPAC Group	IVA
Glawe Number	85
Mendeleev Number	88
Pettifor Number	85
Geochemical Class	major
Goldschmidt Class	litophile
Other
Gas Basicity	814.1 kJ/mol
Dipole Polarizability	37.3 ± 0.7 a₀
C6 Dispersion Coefficient	305 a₀ 308 a₀
Allotropes
Neutron Cross Section	0.166
Neutron Mass Absorption	0.0002
Quantum Numbers	3P0
Space Group	227 (Fd_3m)

Isotopes of Silicon

Stable Isotopes	3
Unstable Isotopes	21
Radioactive Isotopes	21

²²Si

Abundance	Radioactive ☢️
Relative Atomic Mass	22.036114 ± 0.000537 Da
Mass Number	22
G-Factor	0
Half Life	28.7 ± 1.1 ms
Spin	0
Quadrupole Moment	0
Discovery Year	1987
Parity	+

²²Si Decay Modes

Decay Mode	Intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	100%
β⁺ p (β⁺-delayed proton emission)	62%
2p (2-proton emission)	0.7%

²³Si

Abundance	Radioactive ☢️
Relative Atomic Mass	23.025711 ± 0.000537 Da
Mass Number	23
G-Factor
Half Life	42.3 ± 0.4 ms
Spin	3/2
Quadrupole Moment
Discovery Year	1986
Parity	+

²³Si Decay Modes

Decay Mode	Intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	100%
β⁺ p (β⁺-delayed proton emission)	88%
2p (2-proton emission)	3.6%

²⁴Si

Abundance	Radioactive ☢️
Relative Atomic Mass	24.01153543 ± 0.000020904 Da
Mass Number	24
G-Factor	0
Half Life	143.2 ± 2.1 ms
Spin	0
Quadrupole Moment	0
Discovery Year	1979
Parity	+

²⁴Si Decay Modes

Decay Mode	Intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	100%
β⁺ p (β⁺-delayed proton emission)	34.5%

²⁵Si

Abundance	Radioactive ☢️
Relative Atomic Mass	25.004108798 ± 0.000010735 Da
Mass Number	25
G-Factor
Half Life	220.6 ± 1 ms
Spin	5/2
Quadrupole Moment
Discovery Year	1963
Parity	+

²⁵Si Decay Modes

Decay Mode	Intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	100%
β⁺ p (β⁺-delayed proton emission)	35%

²⁶Si

Abundance	Radioactive ☢️
Relative Atomic Mass	25.992333818 ± 0.000000115 Da
Mass Number	26
G-Factor	0
Half Life	2.2453 ± 0.0007 s
Spin	0
Quadrupole Moment	0
Discovery Year	1960
Parity	+

²⁶Si Decay Modes

Decay Mode	Intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	100%

²⁷Si

Abundance	Radioactive ☢️
Relative Atomic Mass	26.986704687 ± 0.000000115 Da
Mass Number	27
G-Factor	0.34608 ± 0.00012
Half Life	4.117 ± 0.014 s
Spin	5/2
Quadrupole Moment	0.063 ± 0.014
Discovery Year	1939
Parity	+

²⁷Si Decay Modes

Decay Mode	Intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	100%

²⁸Si

Abundance	92.2545 ± 0.0037
Relative Atomic Mass	27.97692653442 ± 0.00000000055 Da
Mass Number	28
G-Factor	0
Half Life
Spin	0
Quadrupole Moment	0
Discovery Year	1920
Parity	+

²⁹Si

Abundance	4.672 ± 0.016
Relative Atomic Mass	28.97649466434 ± 0.0000000006 Da
Mass Number	29
G-Factor	-1.110104 ± 0.000006
Half Life
Spin	1/2
Quadrupole Moment	0
Discovery Year	1920
Parity	+

³⁰Si

Abundance	3.0735 ± 0.0021
Relative Atomic Mass	29.973770137 ± 0.000000023 Da
Mass Number	30
G-Factor	0
Half Life
Spin	0
Quadrupole Moment	0
Discovery Year	1924
Parity	+

³¹Si

Abundance	Radioactive ☢️
Relative Atomic Mass	30.975363196 ± 0.000000046 Da
Mass Number	31
G-Factor
Half Life	157.16 ± 0.2 m
Spin	3/2
Quadrupole Moment
Discovery Year	1934
Parity	+

³¹Si Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%

³²Si

Abundance	Radioactive ☢️
Relative Atomic Mass	31.974151538 ± 0.00000032 Da
Mass Number	32
G-Factor	0
Half Life	157 ± 7 y
Spin	0
Quadrupole Moment	0
Discovery Year	1953
Parity	+

³²Si Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%

³³Si

Abundance	Radioactive ☢️
Relative Atomic Mass	32.977976964 ± 0.00000075 Da
Mass Number	33
G-Factor
Half Life	6.18 ± 0.18 s
Spin	3/2
Quadrupole Moment
Discovery Year	1971
Parity	+

³³Si Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%

³⁴Si

Abundance	Radioactive ☢️
Relative Atomic Mass	33.978538045 ± 0.00000086 Da
Mass Number	34
G-Factor	0
Half Life	2.77 ± 0.2 s
Spin	0
Quadrupole Moment	0
Discovery Year	1971
Parity	+

³⁴Si Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%

³⁵Si

Abundance	Radioactive ☢️
Relative Atomic Mass	34.984550111 ± 0.000038494 Da
Mass Number	35
G-Factor	0.46828571428571 ± 0.0011428571428571
Half Life	780 ± 120 ms
Spin	7/2
Quadrupole Moment
Discovery Year	1971
Parity	-

³⁵Si Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%
β⁻ n (β⁻-delayed neutron emission)	5%

³⁶Si

Abundance	Radioactive ☢️
Relative Atomic Mass	35.986649271 ± 0.000077077 Da
Mass Number	36
G-Factor	0
Half Life	503 ± 2 ms
Spin	0
Quadrupole Moment	0
Discovery Year	1971
Parity	+

³⁶Si Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%
β⁻ n (β⁻-delayed neutron emission)	12%

³⁷Si

Abundance	Radioactive ☢️
Relative Atomic Mass	36.992945191 ± 0.000122179 Da
Mass Number	37
G-Factor
Half Life	141 ± 3.5 ms
Spin	5/2
Quadrupole Moment
Discovery Year	1979
Parity	-

³⁷Si Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%
β⁻ n (β⁻-delayed neutron emission)	17%
2n (2-neutron emission)	%

³⁸Si

Abundance	Radioactive ☢️
Relative Atomic Mass	37.995523 ± 0.0001125 Da
Mass Number	38
G-Factor	0
Half Life	63 ± 8 ms
Spin	0
Quadrupole Moment	0
Discovery Year	1979
Parity	+

³⁸Si Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%
β⁻ n (β⁻-delayed neutron emission)	25%

³⁹Si

Abundance	Radioactive ☢️
Relative Atomic Mass	39.002491 ± 0.0001455 Da
Mass Number	39
G-Factor
Half Life	41.2 ± 4.1 ms
Spin	5/2
Quadrupole Moment
Discovery Year	1979
Parity	-

³⁹Si Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%
β⁻ n (β⁻-delayed neutron emission)	33%
2n (2-neutron emission)	%

⁴⁰Si

Abundance	Radioactive ☢️
Relative Atomic Mass	40.006083641 ± 0.000130962 Da
Mass Number	40
G-Factor	0
Half Life	31.2 ± 2.6 ms
Spin	0
Quadrupole Moment	0
Discovery Year	1989
Parity	+

⁴⁰Si Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%
β⁻ n (β⁻-delayed neutron emission)	38%
2n (2-neutron emission)	%

⁴¹Si

Abundance	Radioactive ☢️
Relative Atomic Mass	41.014171 ± 0.000322 Da
Mass Number	41
G-Factor
Half Life	20 ± 2.5 ms
Spin	7/2
Quadrupole Moment
Discovery Year	1989
Parity	-

⁴¹Si Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%
β⁻ n (β⁻-delayed neutron emission)	55%
2n (2-neutron emission)	%

⁴²Si

Abundance	Radioactive ☢️
Relative Atomic Mass	42.018078 ± 0.000322 Da
Mass Number	42
G-Factor	0
Half Life	12.5 ± 3.5 ms
Spin	0
Quadrupole Moment	0
Discovery Year	1990
Parity	+

⁴²Si Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%
β⁻ n (β⁻-delayed neutron emission)	%
2n (2-neutron emission)	%

⁴³Si

Abundance	Radioactive ☢️
Relative Atomic Mass	43.026119 ± 0.000429 Da
Mass Number	43
G-Factor
Half Life
Spin	3/2
Quadrupole Moment
Discovery Year	2002
Parity	-

⁴³Si Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	%
β⁻ n (β⁻-delayed neutron emission)	%
2n (2-neutron emission)	%

⁴⁴Si

Abundance	Radioactive ☢️
Relative Atomic Mass	44.031466 ± 0.000537 Da
Mass Number	44
G-Factor	0
Half Life
Spin	0
Quadrupole Moment	0
Discovery Year	2007
Parity	+

⁴⁴Si Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	%
β⁻ n (β⁻-delayed neutron emission)	%
2n (2-neutron emission)	%

⁴⁵Si

Abundance	Radioactive ☢️
Relative Atomic Mass	45.039818 ± 0.000644 Da
Mass Number	45
G-Factor
Half Life
Spin	3/2
Quadrupole Moment
Discovery Year
Parity	-

⁴⁵Si Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	%
β⁻ n (β⁻-delayed neutron emission)	%
2n (2-neutron emission)	%

History

In 1800, Sir Humphry Davy thought silica to be a compound and not an element; but in 1811, Gay Lussac and Louis Jacques Thénard probably prepared impure amorphous silicon by heating potassium with silicon tetrafluoride. In 1824 Jöns Jakob Berzelius prepared amorphous silicon by the same general method. Henri Deville in 1854 first prepared crystalline silicon, the second allotropic form of the element. From the Latin word silex, silicis, flint

Discoverers	Jöns Berzelius
Discovery Location	Sweden
Discovery Year	1824
Etymology (Name Origin)	Latin: silex, silicus, (flint).
Pronunciation	SIL-i-ken (English)

If breathed in as a fine silica/silicate dust, it may cause chronic respiratory problems

Silicon also has the unusual property that it expands as it freezes

Uses

In the form of sand and clay it is used to make concrete and brick; it is a useful refractory material for high-temperature work, and in the form of silicates it is used in making enamels, pottery, etc. Silica, as sand, is a principal ingredient of glass. Silicon chips are the basis of modern electronic and computing. Silicon carbide, more commonly called carborundum is used in abrasives. 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.

Abundance
Abundance in Earth's crust	282,000 mg/kg
Abundance in Oceans	2.2 mg/L
Abundance in Human Body	0.026 %
Abundance in Meteor	14 %
Abundance in Sun	0.09 %
Abundance in Universe	0.07 %

Nuclear Screening Constants

1	s	0.4255
2	p	4.055
2	s	4.98
3	p	9.7148
3	s	9.0968

Silicon on ChemicalAid

Art & Architecture Thesaurus ID	300011769
Australian Educational Vocabulary ID	scot/3575
BNCF Thesaurus ID	38210
Bibliothèque nationale de France ID	11976956v
Brockhaus Enzyklopädie online ID	silicium
CAS Registry Number	7440-21-3
ChEBI ID	27573
ChemSpider ID	4574465
CosIng number	96140
Cultureel Woordenboek ID	natuurkunde-scheikunde-en-sterrenkunde/silicium
DSSTOX compound identifier	DTXCID5030038
DSSTox substance ID	DTXSID0051441
Den Store Danske ID	silicium
DrugBank ID	12982
ECHA Substance Infocard ID	100.028.300
Encyclopædia Britannica Online ID	science/silicon
Encyclopædia Universalis ID	silicium
Fandom article ID	memory-alpha:Silicon
Freebase ID	/m/025sf80
French Vikidia ID	Silicium
GND ID	4077445-4
Great Russian Encyclopedia Online ID	2109143
HSDB ID	5033
ICSC ID	1508
InChI	InChI=1S/Si
InChIKey	XUIMIQQOPSSXEZ-UHFFFAOYSA-N
KBpedia ID	Silicon
KEGG ID	C06263
LEM ID	LEM201008365
Latvian National Encyclopedia Online ID	117852
Library of Congress authority ID	sh85122512
MeSH descriptor ID	D012825
NALT ID	55167
NKCR AUT ID	ph122083
Namuwiki ID	규소
National Diet Library ID	00565390
National Library of Israel J9U ID	987007543750105171
OmegaWiki Defined Meaning	3421
OpenAlex ID	C544956773
PSH ID	5797
PubChem CID	5461123
RxNorm ID	9774
Römpp online ID	RD-19-02444
Store norske leksikon ID	silisium
Treccani ID	silicio
UK Parliament thesaurus ID	12808
UNII	Z4152N8IUI
UNSPSC Code	12141911
Wolfram Language entity code	Entity["Mineral", "Silicon"]
WordNet 3.1 Synset ID	14678720-n
YSO ID	15609
ZVG number	8110

Silicon (Si)

Properties

Isotopes of Silicon

22Si

22Si Decay Modes

23Si

23Si Decay Modes

24Si

24Si Decay Modes

25Si

25Si Decay Modes

26Si

26Si Decay Modes

27Si

27Si Decay Modes

28Si

29Si

30Si

31Si

31Si Decay Modes

32Si

32Si Decay Modes

33Si

33Si Decay Modes

34Si

34Si Decay Modes

35Si

35Si Decay Modes

36Si

36Si Decay Modes

37Si

37Si Decay Modes

38Si

38Si Decay Modes

39Si

39Si Decay Modes

40Si

40Si Decay Modes

41Si

41Si Decay Modes

42Si

42Si Decay Modes

43Si

43Si Decay Modes

44Si

44Si Decay Modes

45Si

45Si Decay Modes