Silicon

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 Number14
Atomic Weight28.085
Mass Number28
Group14
Period3
Blockp
Protons14 p+
Neutrons14 n0
Electrons14 e-
SiliconCroda.jpg Silicon-unit-cell-3D-balls.png Animated Bohr Model of Si (Silicon) Enhanced Bohr Model of Si (Silicon) Bohr Model: Si (Silicon) Orbital Diagram of Si (Silicon)

Properties

Atomic Radius
110 pm
Molar Volume
Covalent Radius
116 pm
Metallic Radius
117 pm
Ionic Radius
26 pm
Crystal Radius
40 pm
Van der Waals Radius
210 pm
Density
2.3296 g/cm³
Energy
Proton Affinity
837 kJ/mol
Electron Affinity
1.3895211 eV/particle
Ionization Energy
8.151683 eV/particle
Heat of Vaporization
383 kJ/mol
Heat of Fusion
50.6 kJ/mol
Heat of Formation
450 kJ/mol
Electrons
Electron Shells2, 8, 4
Valence Electrons4
Electron Configuration[Ne] 3s2 3p2
Oxidation States-4, -3, -2, -1, 0, 1, 2, 3, 4
Electronegativity
1.9
Electrophilicity
1.6827934805482991 eV/particle
Phases
PhaseSolid
Gas Phase
Boiling Point
3,538.15 K
Melting Point
1,687.15 K
Critical Pressure
Critical Temperature
Triple Point
Visual
Color
Gray
Appearancecrystalline, reflective with bluish-tinged faces
Refractive Index
Thermodynamic Properties
Thermal Conductivity
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
TypeSemiconductor
Electrical Conductivity
0.001 MS/m
Electrical Resistivity
0.001 m Ω
Superconducting Point
Magnetism
Typediamagnetic
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 StructureTetrahedral Packing (DIA)
Lattice Constant
5.43 Å
Lattice Anglesπ/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
CategoryMetalloids, Metalloids
CAS GroupIVB
IUPAC GroupIVA
Glawe Number85
Mendeleev Number88
Pettifor Number85
Geochemical Classmajor
Goldschmidt Classlitophile
Other
Gas Basicity
814.1 kJ/mol
Dipole Polarizability
37.3 ± 0.7 a₀
C6 Dispersion Coefficient
305 a₀
Allotropes
Neutron Cross Section
0.166
Neutron Mass Absorption
0.0002
Quantum Numbers3P0
Space Group227 (Fd_3m)

Isotopes of Silicon

Stable Isotopes3
Unstable Isotopes21
Radioactive Isotopes21

22Si

AbundanceRadioactive ☢️
Relative Atomic Mass
22.036114 ± 0.000537 Da
Mass Number22
G-Factor
0
Half Life
28.7 ± 1.1 ms
Spin0
Quadrupole Moment
0
Discovery Year1987
Parity+

22Si Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%
β+ p (β+-delayed proton emission)62%
2p (2-proton emission)0.7%

23Si

AbundanceRadioactive ☢️
Relative Atomic Mass
23.025711 ± 0.000537 Da
Mass Number23
G-Factor
Half Life
42.3 ± 0.4 ms
Spin3/2
Quadrupole Moment
Discovery Year1986
Parity+

23Si Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%
β+ p (β+-delayed proton emission)88%
2p (2-proton emission)3.6%

24Si

AbundanceRadioactive ☢️
Relative Atomic Mass
24.01153543 ± 0.000020904 Da
Mass Number24
G-Factor
0
Half Life
143.2 ± 2.1 ms
Spin0
Quadrupole Moment
0
Discovery Year1979
Parity+

24Si Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%
β+ p (β+-delayed proton emission)34.5%

25Si

AbundanceRadioactive ☢️
Relative Atomic Mass
25.004108798 ± 0.000010735 Da
Mass Number25
G-Factor
Half Life
220.6 ± 1 ms
Spin5/2
Quadrupole Moment
Discovery Year1963
Parity+

25Si Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%
β+ p (β+-delayed proton emission)35%

26Si

AbundanceRadioactive ☢️
Relative Atomic Mass
25.992333818 ± 0.000000115 Da
Mass Number26
G-Factor
0
Half Life
2.2453 ± 0.0007 s
Spin0
Quadrupole Moment
0
Discovery Year1960
Parity+

26Si Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%

27Si

AbundanceRadioactive ☢️
Relative Atomic Mass
26.986704687 ± 0.000000115 Da
Mass Number27
G-Factor
0.34608 ± 0.00012
Half Life
4.117 ± 0.014 s
Spin5/2
Quadrupole Moment
0.063 ± 0.014
Discovery Year1939
Parity+

27Si Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%

28Si

Abundance
92.2545 ± 0.0037
Relative Atomic Mass
27.97692653442 ± 0.00000000055 Da
Mass Number28
G-Factor
0
Half Life
Spin0
Quadrupole Moment
0
Discovery Year1920
Parity+

29Si

Abundance
4.672 ± 0.016
Relative Atomic Mass
28.97649466434 ± 0.0000000006 Da
Mass Number29
G-Factor
-1.110104 ± 0.000006
Half Life
Spin1/2
Quadrupole Moment
0
Discovery Year1920
Parity+

30Si

Abundance
3.0735 ± 0.0021
Relative Atomic Mass
29.973770137 ± 0.000000023 Da
Mass Number30
G-Factor
0
Half Life
Spin0
Quadrupole Moment
0
Discovery Year1924
Parity+

31Si

AbundanceRadioactive ☢️
Relative Atomic Mass
30.975363196 ± 0.000000046 Da
Mass Number31
G-Factor
Half Life
157.16 ± 0.2 m
Spin3/2
Quadrupole Moment
Discovery Year1934
Parity+

31Si Decay Modes
Decay ModeIntensity
β (β decay)100%

32Si

AbundanceRadioactive ☢️
Relative Atomic Mass
31.974151538 ± 0.00000032 Da
Mass Number32
G-Factor
0
Half Life
157 ± 7 y
Spin0
Quadrupole Moment
0
Discovery Year1953
Parity+

32Si Decay Modes
Decay ModeIntensity
β (β decay)100%

33Si

AbundanceRadioactive ☢️
Relative Atomic Mass
32.977976964 ± 0.00000075 Da
Mass Number33
G-Factor
Half Life
6.18 ± 0.18 s
Spin3/2
Quadrupole Moment
Discovery Year1971
Parity+

33Si Decay Modes
Decay ModeIntensity
β (β decay)100%

34Si

AbundanceRadioactive ☢️
Relative Atomic Mass
33.978538045 ± 0.00000086 Da
Mass Number34
G-Factor
0
Half Life
2.77 ± 0.2 s
Spin0
Quadrupole Moment
0
Discovery Year1971
Parity+

34Si Decay Modes
Decay ModeIntensity
β (β decay)100%

35Si

AbundanceRadioactive ☢️
Relative Atomic Mass
34.984550111 ± 0.000038494 Da
Mass Number35
G-Factor
0.46828571428571 ± 0.0011428571428571
Half Life
780 ± 120 ms
Spin7/2
Quadrupole Moment
Discovery Year1971
Parity-

35Si Decay Modes
Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)5%

36Si

AbundanceRadioactive ☢️
Relative Atomic Mass
35.986649271 ± 0.000077077 Da
Mass Number36
G-Factor
0
Half Life
503 ± 2 ms
Spin0
Quadrupole Moment
0
Discovery Year1971
Parity+

36Si Decay Modes
Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)12%

37Si

AbundanceRadioactive ☢️
Relative Atomic Mass
36.992945191 ± 0.000122179 Da
Mass Number37
G-Factor
Half Life
141 ± 3.5 ms
Spin5/2
Quadrupole Moment
Discovery Year1979
Parity-

37Si Decay Modes
Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)17%
2n (2-neutron emission)%

38Si

AbundanceRadioactive ☢️
Relative Atomic Mass
37.995523 ± 0.0001125 Da
Mass Number38
G-Factor
0
Half Life
63 ± 8 ms
Spin0
Quadrupole Moment
0
Discovery Year1979
Parity+

38Si Decay Modes
Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)25%

39Si

AbundanceRadioactive ☢️
Relative Atomic Mass
39.002491 ± 0.0001455 Da
Mass Number39
G-Factor
Half Life
41.2 ± 4.1 ms
Spin5/2
Quadrupole Moment
Discovery Year1979
Parity-

39Si Decay Modes
Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)33%
2n (2-neutron emission)%

40Si

AbundanceRadioactive ☢️
Relative Atomic Mass
40.006083641 ± 0.000130962 Da
Mass Number40
G-Factor
0
Half Life
31.2 ± 2.6 ms
Spin0
Quadrupole Moment
0
Discovery Year1989
Parity+

40Si Decay Modes
Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)38%
2n (2-neutron emission)%

41Si

AbundanceRadioactive ☢️
Relative Atomic Mass
41.014171 ± 0.000322 Da
Mass Number41
G-Factor
Half Life
20 ± 2.5 ms
Spin7/2
Quadrupole Moment
Discovery Year1989
Parity-

41Si Decay Modes
Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)55%
2n (2-neutron emission)%

42Si

AbundanceRadioactive ☢️
Relative Atomic Mass
42.018078 ± 0.000322 Da
Mass Number42
G-Factor
0
Half Life
12.5 ± 3.5 ms
Spin0
Quadrupole Moment
0
Discovery Year1990
Parity+

42Si Decay Modes
Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)%
2n (2-neutron emission)%

43Si

AbundanceRadioactive ☢️
Relative Atomic Mass
43.026119 ± 0.000429 Da
Mass Number43
G-Factor
Half Life
Spin3/2
Quadrupole Moment
Discovery Year2002
Parity-

43Si Decay Modes
Decay ModeIntensity
β (β decay)%
β n (β-delayed neutron emission)%
2n (2-neutron emission)%

44Si

AbundanceRadioactive ☢️
Relative Atomic Mass
44.031466 ± 0.000537 Da
Mass Number44
G-Factor
0
Half Life
Spin0
Quadrupole Moment
0
Discovery Year2007
Parity+

44Si Decay Modes
Decay ModeIntensity
β (β decay)%
β n (β-delayed neutron emission)%
2n (2-neutron emission)%

45Si

AbundanceRadioactive ☢️
Relative Atomic Mass
45.039818 ± 0.000644 Da
Mass Number45
G-Factor
Half Life
Spin3/2
Quadrupole Moment
Discovery Year
Parity-

45Si Decay Modes
Decay ModeIntensity
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

DiscoverersJöns Berzelius
Discovery LocationSweden
Discovery Year1824
Etymology (Name Origin)Latin: silex, silicus, (flint).
PronunciationSIL-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

1s0.4255
2p4.055
2s4.98
3p9.7148
3s9.0968