1. General Information
- Symbol: Si
- Atomic Number: 14
- Atomic Mass: 28.09 u
- Group: 14 (Carbon Group)
- Period: 3
- Block: p-block
- Electron Configuration: 1s² 2s² 2p⁶ 3s² 3p²
- Valence Electrons: 4
- Phase at Room Temperature: Solid
2. Isotopes of Silicon
| Isotope |
Protons |
Neutrons |
Abundance |
Notes |
| ²⁸Si |
14 |
14 |
92.23% |
Most abundant. |
| ²⁹Si |
14 |
15 |
4.67% |
Stable. |
| ³⁰Si |
14 |
16 |
3.1% |
Stable. |
3. Physical Properties
- Color: Gray with metallic luster
- Odor: Odorless
- Density: 2.33 g/cm³
- Melting Point: 1,414°C
- Boiling Point: 3,265°C
- State at STP: Solid
- Hardness: Brittle, crystalline structure (like glass).
4. Chemical Properties
- Moderately Reactive:
- Forms silicon dioxide (SiO₂) in air.
- Resists corrosion by water and acids but reacts with halogens.
- Forms Covalent Bonds:
- Tetravalent (can form four bonds).
- Semiconductor Properties:
- Conducts electricity better than non-metals but worse than metals.
Reaction with Oxygen (Oxidation):
Si + O₂ → SiO₂ (Silicon Dioxide)
Reaction with Hydrofluoric Acid:
SiO₂ + 6HF → H₂SiF₆ + 2H₂O
5. Occurrence and Abundance
- Second most abundant element in Earth’s crust (after oxygen).
- Found in:
- Rocks and Sand: Quartz, granite, feldspar.
- Silicates: Form the majority of Earth’s minerals.
- Not found in Free State: Always in compounds (e.g., SiO₂).
6. Industrial Production of Silicon
7. Uses of Silicon
| Application |
Description |
| Semiconductors |
Microchips, transistors, solar cells. |
| Construction |
Concrete, glass, and bricks. |
| Alloys |
Aluminium-silicon alloys for automotive parts. |
| Cosmetics and Sealants |
Silicone-based products. |
| Glass and Ceramics |
Silica (SiO₂) used in glassmaking. |
| Aerospace and Defense |
High-strength silicon carbide (SiC). |
| Medical Implants |
Silicone for surgical implants. |
8. Important Silicon Compounds
| Compound |
Formula |
Use |
| Silicon Dioxide |
SiO₂ |
Glass, sand, concrete. |
| Silicones |
(R₂SiO)n |
Lubricants, sealants, medical devices. |
| Silicon Carbide |
SiC |
Abrasives, cutting tools. |
| Silicon Tetrachloride |
SiCl₄ |
Optical fibers, semiconductors. |
| Sodium Silicate |
Na₂SiO₃ |
Detergents, water treatment. |
9. Biological Importance of Silicon
- Trace Element in Humans and Plants:
- Supports bone strength and connective tissue.
- Promotes plant growth and cell wall strength.
- Essential for Diatoms: Microscopic algae use silica to form protective shells.
10. Silicon in Technology
- Key Material in Electronics:
- Used in transistors and microchips for computers and phones.
- Solar Panels:
- Photovoltaic cells are made from silicon wafers.
- Silicon Valley:
- Named after the use of silicon in the tech industry.
11. Environmental Role of Silicon
- Rock Cycle:
- Forms minerals that shape Earth’s crust and geological processes.
- Silica Dust:
- Can cause lung diseases (silicosis) if inhaled.
- Sustainable and Abundant:
- Silicon-based materials are widely recyclable.
12. Safety and Hazards
- Inert in Pure Form:
- Does not pose direct health risks.
- Silica Dust (SiO₂):
- Prolonged exposure can lead to respiratory issues.
- Silicon Compounds:
- Some are corrosive (e.g., SiCl₄ reacts with moisture to form HCl).
Handling Precautions:
- Ventilation when working with silica dust.
- Use respirators and safety goggles during cutting or grinding.
Fun Facts About Silicon:
- Named after the Latin word “silex” meaning flint or hard stone.
- Silicon makes up 27% of Earth’s crust.
- Silicon-based life forms are a common science fiction trope!
- The first transistor was made from silicon and germanium.