Great — now we move to **Radon (Rn, atomic number 86).**
⚠️ Radon is a **radioactive noble gas**, produced naturally from the decay of **uranium, thorium, and radium** in rocks and soils. It is not chemically extracted like metals; instead, it is **collected, separated, and purified** from sources where it naturally forms.
Here are the **20 most common methods of extracting Radon**:
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# **20 Most Common Methods of Extracting Radon**
### **A. Natural Occurrence & Collection**
1. **Collection from Uranium-Rich Soils** – Soil gas sampling for radon measurement.
2. **Extraction from Groundwater** – Pumping water from aquifers, where radon is dissolved.
3. **Collection from Mine Air** – Historic and modern sampling in uranium/coal mines.
4. **Emanation from Granite & Phosphate Rocks** – Passive release from minerals.
5. **Recovery from Building Basements/Crawlspaces** – Used in environmental monitoring.
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### **B. Radium-Based Production (Lab Scale)**
6. **Decay of Radium-226** – Classic method, since ^226Ra → ^222Rn naturally.
7. **Encapsulation of Radium Salts** – Traps radon as it decays out of RaCl₂ or Ra(NO₃)₂.
8. **Radon Extraction Chambers (Radium Sources)** – Radon collected by pumping gas.
9. **Continuous Flow Radon Generators** – Radium solution produces radon continuously for calibration.
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### **C. Collection & Trapping Methods**
10. **Activated Charcoal Adsorption** – Standard technique for capturing radon from air.
11. **Zeolite Molecular Sieve Adsorption** – Selectively traps noble gases including radon.
12. **Cryogenic Cooling (Cold Traps)** – Radon condenses at low temperatures.
13. **Liquid Nitrogen Trapping** – Efficient for isolating radon from mixed gases.
14. **Membrane Separation (Gas Diffusion)** – Selectively enriches radon gas.
15. **Electrostatic Precipitation** – Collects radon daughters, indirectly concentrating radon.
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### **D. Measurement-Oriented Extraction**
16. **Scintillation Cells (Lucas Cells)** – Small chambers filled with extracted radon for detection.
17. **Liquid Scintillator Absorption** – Dissolves radon in liquid for radiation counting.
18. **Fluorescence Track Detectors (Solid-State Passive Collection)** – Detects radon after adsorption.
19. **Radon-in-Oil Absorption** – Dissolving radon into mineral oil for lab studies.
20. **Continuous Airflow Pumping into Detection Chambers** – Used in environmental radon monitoring.
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✅ **Summary:**
* **Main practical source**: radon comes from **radium decay** (especially ^226Ra).
* **Collection techniques**: adsorption on charcoal/zeolite, cryogenic cooling, and gas transfer.
* **Modern usage**: mostly in **environmental monitoring, health studies, and calibration of detectors**.
* **Historical use**: radon was once used in **radon therapy** (now obsolete due to cancer risk).
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Next in order is **Francium (Fr, atomic number 87).**
Would you like me to list the **20 most common methods of extracting Francium** (even though it’s the rarest alkali metal)?
