S

Silicon

IUPAC: Silicon

Si Elements CAS 7440-21-3
Quick Reference
Formula / NotationSi
CAS Number7440-21-3
Molecular Weight28.09
Melting Point1414.0
Boiling Point3265.0
Density2.33
SolubilityInsoluble in water
AppearanceDark grey with blue-metallic lustre, brittle crystalline
Also Known AsSi, silicon element
CategoryElements

What is Silicon?

Silicon is a lustrous metalloid, atomic number 14, second most abundant element in Earth crust (28%). Pure silicon is a semiconductor - foundation of modern electronics. Forms SiO2 (silica) and silicates making up most rocks.

Formula & Notation

Si

IUPAC Name: Silicon

Other Names / Synonyms: Si, silicon element

Properties & Characteristics

Atomic number: 14. Atomic mass: 28.086 g/mol. Period 3, Group 14 (metalloid). Melting point: 1414 C. Boiling point: 3265 C. Density: 2.33 g/cm3. Band gap: 1.12 eV. Electronegativity: 1.90. Isotopes: Si-28 (92.2%), Si-29, Si-30.

Physical Data

PropertyValue
Melting Point1414.0
Boiling Point3265.0
Density2.33
Molecular Weight28.09
SolubilityInsoluble in water
AppearanceDark grey with blue-metallic lustre, brittle crystalline

Uses & Applications

Semiconductor devices (transistors, ICs, solar cells). Glass and ceramics. Concrete (silicates). Silicone polymers (sealants, implants). Computer chips. Abrasives (SiC). Optical fibres. Photovoltaic cells.

Safety Information

Silicon dust (crystalline silica SiO2): severe lung hazard - causes silicosis with chronic inhalation (OSHA PEL 50 ug/m3). Silicon metal dust: irritant. Silane (SiH4) production: pyrophoric gas. Handle with respiratory protection.

Always consult the SDS/MSDS before handling any chemical. This information is for educational purposes only.

Key Facts

Term Silicon
Formula Si
CAS Number 7440-21-3
Molecular Weight 28.09
Category Elements
Synonyms Si, silicon element

Frequently Asked Questions

Silicon is a lustrous metalloid, atomic number 14, second most abundant element in Earth crust (28%). Pure silicon is a semiconductor - foundation of modern electronics. Forms SiO2 (silica) and silicates making up most rocks.

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