An atom consists of a nucleus (containing protons and neutrons) surrounded by electrons in shells. Some atoms are radioactive because they have unstable nuclei with either too many protons or neutrons. These atoms undergo radioactive decay to achieve stability.
Click the button to simulate radioactive decay using virtual cubes. Green shows undecayed atoms, red shows decayed atoms.
| Type | Description | Penetrating Power | Shielding Required |
|---|---|---|---|
| Alpha (α) | Helium nucleus (2 protons + 2 neutrons) | Very low - stopped by paper | Paper or skin |
| Beta (β) | High-speed electron | Medium - stopped by aluminum | Thin metal sheet |
| Gamma (γ) | Electromagnetic radiation | Very high - passes through most materials | Thick lead or concrete |
Given the following data for Phosphorus-32, plot the activity vs. time and determine its half-life:
| Time (days) | 0 | 2 | 4 | 6 | 8 |
|---|---|---|---|---|---|
| Activity (Bq) | 100 | 87 | 76 | 66 | 57 |
Given the following data for Radon-222, plot the activity vs. time and determine its half-life:
| Time (days) | 0 | 1 | 2 | 3 | 4 |
|---|---|---|---|---|---|
| Activity (Bq) | 100 | 82 | 67 | 55 | 45 |
Phosphorus-32 Half-life: ~14.3 days
Radon-222 Half-life: ~3.8 days
| Isotope | Applications | Problems/Risks |
|---|---|---|
| Americium-241 |
- Smoke detectors in homes - Industrial thickness gauges |
- Long half-life (432 years) - Toxic if ingested/inhaled - Proper disposal required |
| Cobalt-60 |
- Cancer treatment (radiotherapy) - Food sterilization - Industrial radiography |
- Strong gamma emitter - Requires heavy shielding - Potential environmental hazard |
| Iodine-131 |
- Thyroid cancer treatment - Diagnostic imaging |
- Can affect healthy thyroid tissue - Requires careful dosage control |
| Benefits | Drawbacks |
|---|---|
|
- Early detection of fires (smoke detectors) - Precise medical treatments - Non-destructive testing in industry - Extended food preservation - Accurate thickness measurements |
- Potential radiation exposure - Complex disposal procedures - High security requirements - Training needed for safe handling - Environmental concerns |
The use of Tritium in exit signs is a justified application of radioactive materials in public and commercial spaces for several compelling reasons:
Although special disposal procedures are necessary, Tritium exit signs provide an essential life-saving function in emergency situations by clearly indicating exits. The risk posed by properly manufactured and installed Tritium signs is negligible compared to the safety benefits they offer.
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Release of radioactive materials including Iodine-131, Cesium-137, and Strontium-90
Immediate evacuation of nearby populations, acute radiation syndrome in workers
Contamination of soil and water, increased cancer risks, exclusion zone establishment
| Isotope | Half-life | Environmental Impact | Current Status (2024) |
|---|---|---|---|
| Iodine-131 | 8 days | Initial thyroid exposure risk | No longer present |
| Cesium-137 | 30 years | Soil contamination, food chain | ~50% of original remains |
| Strontium-90 | 29 years | Bone seeker, water contamination | ~50% of original remains |
| Plutonium-239 | 24,100 years | Long-term soil contamination | Nearly all still present |