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Atomic: M.A.C. | Reference
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Electron Configuration 2,8,4
Electron Configuration [Ne] 3s2 3p2
Ground state 3P0
Atomic Volume 12.1 g/cm3
Electronegativity 1.90
Magnetic ordering Non-magnetic
Mass magnetic susceptibility -1.6 x 10-9
Molar magnetic susceptibility -4.49 x 10-11
Speed of sound 8433 m s-1
Thermal Properties
Enthalpy of Atomization 439.3 kJ mol-1 @25°C
Enthalpy of Fusion 39.6 kJ mol-1
Enthalpy of Vaporisation 383.3 kJ mol-1
Heat Capacity 19.789 J mol-1 K-1
Thermal Conductivity 149 W m-1 K-1
Thermal Expansion 2.6 μm m-1 K-1
Hardness
Mohs hardness 6.5
Elastic Properties
Bulk modulus 100 GPa
Young's modulus 47 GPa
Electrical Properties
Electrical resistivity No data.
Electrical conductivity No data.
Chemical Properties
Electrochemical Equivalent 0.26197 g Ah-1
Electron Work Function 4.52 eV
Valence Electron Potential (-eV) 144
Ionization Potential  
First 8.151
Second 16.345
Third 33.492
Incompatibilities Chlorine, fluorine, oxidizers, calcium, caesium carbide (Cs2C2), alkaline carbonates.
Flammability
Combustible Solid in powder form
Energy Levels
Kα1 (intensity 100) 1.73998 KeV
Kα2 (intensity 0) 1.73938 KeV
Kβ1 (intensity 1.7) 1.83594 KeV
Lα1 (intensity 100) 0.06 KeV
Lγ3 (intensity 0) 0.089 KeV
Ll (intensity 100) 0.06 KeV
Atomic Radii
Empirical 110 pm
Bohr Radius 111 pm
Covalent Radius 111 pm
Van der Waals 210 pm
Triple covalent 102 pm
Metallic No data.
Ionic Radii (Å)
Charge Coordination Crystal Ionic Key
IV 0.4 0.26 *
VI 0.54 0.4 R*
R, From r3 vs V plots.
C, Calculated from bond length - bond strength equations.
E, Estimated.
*, Most Reliable.
M, From Metallic Oxides.
A, Ahrens (1952) Ionic radius.
P, Pauling's (1960) Crystal Radius.
Oxidation States
Main Si+2, Si+4
Other
Ionisation Energies (kJ mol-1) show graph
M - M+ 786.5
M+ - M2+ 1577.1
M2+ - M3+ 3231.4
M3+ - M4+ 4355.5
M4+ - M5+ 16091
M5+ - M6+ 19784
M6+ - M7+ 23786
M7+ - M8+ 29252
M8+ - M9+ 33876
M9+ - M10+ 38732
Covalent Bonds (kJ mol-1)
Si-H 326
Si-C 301
Si-O 486
Si-F 582
Si-Cl 391
Si-Si 226
Vapour Pressure
P (Pa) 1 10 100 1K 10K 100K
T (K) 1908 2102 2339 2636 3021 3537
Crystal Structure
Structure Diamond
a = 543.09 pm
b = 543.09 pm
c = 543.09 pm
α = 90°
β = 90°
γ = 90°