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1. General Information
- Symbol: Ar
- Atomic Number: 18
- Atomic Mass: 39.95 u
- Group: 18 (Noble Gases)
- Period: 3
- Block: p-block
- Electron Configuration: 1s² 2s² 2p⁶ 3s² 3p⁶
- Valence Electrons: 8 (Full outer shell)
- Phase at Room Temperature: Gas
2. Isotopes of Argon
Isotope | Protons | Neutrons | Abundance | Notes |
---|---|---|---|---|
³⁶Ar | 18 | 18 | 0.34% | Stable. |
³⁸Ar | 18 | 20 | 0.06% | Stable. |
⁴⁰Ar | 18 | 22 | 99.6% | Most abundant. |
3. Physical Properties
- Color: Colorless
- Odor: Odorless
- Density: 1.784 g/L (at STP)
- Melting Point: -189.3°C
- Boiling Point: -185.8°C
- State at STP: Gas
- Conductivity: Poor conductor of heat and electricity.
4. Chemical Properties
- Inert and Non-Reactive:
- Full outer electron shell makes argon chemically stable.
- Does not form compounds under normal conditions.
- Non-Flammable and Non-Toxic.
- Under Extreme Conditions:
- Can form argon fluorohydride (HArF) at extremely low temperatures.
5. Occurrence and Abundance
- Third most abundant gas in Earth’s atmosphere (0.93%).
- Found in:
- Air (by volume): Extracted during liquid air distillation.
- Mineral Decay: Produced through the radioactive decay of potassium-40 (K-40).
- In the Universe: 12th most abundant element.
6. Industrial Production of Argon
- Fractional Distillation of Liquid Air:
- Argon is separated during the production of liquid oxygen and nitrogen.
Air → Argon + Oxygen + Nitrogen (Distillation)
7. Uses of Argon
Application | Description |
---|---|
Welding and Metalworking | Provides inert atmosphere for arc welding. |
Lighting | Fills incandescent and fluorescent bulbs. |
Lasers | Argon-ion lasers used in surgery and optics. |
Food Preservation | Replaces oxygen to prevent spoilage. |
Electronics | Protects silicon crystals during manufacturing. |
Fire Suppression Systems | Displaces oxygen to smother fires. |
Scientific Research | Used in cryogenics and particle detection. |
8. Important Argon Applications
- Incandescent Bulbs: Extends the life of the filament by preventing oxidation.
- Double-Glazed Windows: Argon gas between panes improves insulation.
- 3D Printing: Creates inert environments for metal printing.
- Medical Lasers: Argon lasers are used in eye surgery and dermatology.
9. Biological Role of Argon
- No known biological function.
- Non-toxic and inert – Safe for use in food and medical applications.
10. Argon in Environmental Chemistry
- Stable in the Environment: Argon does not react or degrade.
- Radioactive Decay Product: Argon-40 forms through potassium-40 decay, important in geological dating.
11. Safety and Hazards
- Asphyxiation Risk:
- Argon can displace oxygen in confined spaces, leading to suffocation.
- Handling Precautions:
- Use in well-ventilated areas.
- Store in pressurized cylinders.
- Non-Flammable: No risk of fire or explosion.
Fun Facts About Argon:
- Argon means “lazy” in Greek, referencing its inert nature.
- Discovered in 1894 by Lord Rayleigh and Sir William Ramsay.
- Argon lasers are used in holography and surgery.
- The blue glow in neon signs is often from argon gas, not neon!