Silicon - Si

Symbol: Si
Atomic Number: 14
Atomic Weight: 28.0855
Element Classification: Semimetallic
Discovered By: Jons Jacob Berzelius
Discovery Date: 1824 (Sweden)
Name Origin: Latin: silex, silicus, (flint).

Density (g/cc): 2.33
Melting Point (K): 1683
Boiling Point (K): 2628
Appearance: Amorphous form is brown powder; crystalline form has a gray
Atomic Radius (pm): 132
Atomic Volume (cc/mol): 12.1
Covalent Radius (pm): 111
Ionic Radius: 42 (+4e) 271 (-4e)
Specific Heat (@20C J/g mol): 0.703
Fusion Heat (kJ/mol): 50.6
Evaporation Heat (kJ/mol): 383
Thermal Conductivity (@25C W/m K):
Debye Temperature (K): 625.00
Pauling Negativity Number: 1.90
First Ionizing Energy (kJ/mol): 786.0
Oxidation States: 4, -4
Electronic Configuration: [Ne] 3s2 3p2
Lattice Structure: Diagonal (DIA)
Lattice Constant (): 5.430
Lattice C/A Ratio: n/a

Mineral Hardness [no units]: 6.5

Note: Silicon is a relatively hard, brittle material, which does not respond well to grinding with large silicon carbide abrasives. Silicon carbide papers contain strongly bonded abrasive particles which, when they collide with the leading edge of a piece of silicon, create significant impact damage. In addition, they create tensile stresses on the trailing edge of silicon, which results in deep and destructive cracking. Cutting close to the target area is preferable to grinding, but to accurately approach the target area within a silicon device, fine grinding is still necessary.

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