Silicon

CAS Number
7440-21-3
EC Number
231-130-8
Abbreviation
Si

What is Silicon?

Silicon (CAS 7440-21-3), commonly traded as silicon metal or Si, is a high-purity elemental material refined from quartz; a foundational raw material for metallurgical, chemical, and electronic manufacturing supply chains.

Where is Silicon used?

  • Plastics and polymers: primary feedstock for silicone polymers such as fluids, elastomers, and sealants for automotive and construction
  • Automotive: aluminum-silicon alloys for lightweight, high-strength castings in engine components and structural parts
  • Electronics: ultra-high-purity wafers as substrate for semiconductors, solar cells, and integrated circuits
  • Chemical synthesis: starting material for chlorosilanes and other organosilicon intermediates
  • It functions primarily as a precursor for producing silicones, semiconductors, and aluminum alloys.

Good to know: Metallurgical grade (typically 98–99% Si) covers alloy and chemical synthesis applications, while semiconductor and solar grades are held to significantly tighter purity thresholds.

Commercial specifications

  • Particle size and purity grade selected based on end-use requirements
  • Metallurgical grade typically 98–99% Si
  • Standard packaging ranges from bulk bags to drums

Other Names (Synonyms)

element 14|14Si|Silicon metal|Defoamer S-10|Silicon, elemental|Silicium|Z4152N8IUI|Elemental silicon|Si

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What are the physical properties of Silicon?

Melting Point 1410 °C
Boiling Point 2355 °C
Density 2.33 g/cm³ @ Temp: 25 °C
Flash Point 2.33 °C
Appearance Silicon is a nonmetallic element which is known as silicon metal. Not occur freely in nature, but is found in silicon dioxide (silica) and in various silicates. It is a steel-gray crystalline solid or a black-brown amorphous material.
Color White
Odor Odorless
Form powder
Water Solubility INSOLUBLE
Refractive Index 3.9766
pH 13.5 (H2O, 20°C)

How is Silicon classified and handled safely? Learn More

Danger
GHS02· Flammable

Hazard Statements

H228 Flammable solid
H320 Causes eye irritation

Precautionary Statements

P210 Keep away from heat, hot surfaces, sparks, open flames and other ignition sources. No smoking.
P240 Ground and bond container and receiving equipment.
P241 Use explosion-proof [electrical/ventilating/lighting/…] equipment.
P280 Wear protective gloves/protective clothing/eye protection/face protection.

Which trade and regulatory codes apply to Silicon?

HS Code 28046900
UN Number 2922
ADR Class 8
Packing Group II
Storage Class 4.1B - Flammable solid hazardous materials
WGK (Germany) 2
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