Half-Life of Radioactive Elements
What Is Half-Life
Half-life is the period required for half of the atoms in a radioactive substance to undergo decay. This fundamental concept is pivotal in understanding the stability and longevity of radioactive materials.
Radioisotopes and Their Significance
Radioisotopes are unstable atoms that emit radiation as they decay into more stable forms. They play a crucial role in fields such as medicine, archaeology, and environmental science.
Applications of Radioisotopes
- Medical Imaging and Treatment: Radioisotopes like Iodine-131 are used in diagnosing and treating thyroid conditions.
- Archaeological Dating: Carbon-14 helps determine the age of ancient artifacts.
- Environmental Monitoring: Cesium-137 tracks pollution and contamination levels.
How to Calculate Half-Life
Calculating the half-life of a radioisotope involves understanding its decay rate. While the process is based on exponential decay principles, it can be approached by measuring the quantity of the substance over time.
- Measure Initial Quantity: Determine the starting amount of the radioisotope.
- Monitor Decay: Track the reduction in quantity over specific time intervals.
- Apply Decay Rate: Use the consistent decay rate to estimate the time required for the quantity to halve.
Half-Life of Common Radioactive Elements
|
Element |
Isotope |
Half-Life |
Decay Mode |
|
Carbon (C) |
Carbon-14 |
5,730 years |
Beta decay |
|
Uranium (U) |
Uranium-238 |
4.468 billion years |
Alpha decay |
|
Uranium (U) |
Uranium-235 |
703.8 million years |
Alpha decay |
|
Radon (Rn) |
Radon-222 |
3.8 days |
Alpha decay |
|
Thorium (Th) |
Thorium-232 |
14.05 billion years |
Alpha decay |
|
Plutonium (Pu) |
Plutonium-239 |
24,100 years |
Alpha decay |
|
Iodine (I) |
Iodine-131 |
8.02 days |
Beta decay |
|
Cobalt-60 |
5.27 years |
Beta decay and gamma emission |
|
|
Polonium (Po) |
Polonium-210 |
138.4 days |
Alpha decay |
|
Radium (Ra) |
Radium-226 |
1,600 years |
Alpha decay |
|
Strontium (Sr) |
Strontium-90 |
28.8 years |
Beta decay |
|
Cesium-137 |
30.1 years |
Beta decay |
|
|
Krypton (Kr) |
Krypton-85 |
10.76 years |
Beta decay |
|
Neptunium (Np) |
Neptunium-239 |
2.36 days |
Beta decay |
|
Tritium (H) |
Tritium-3 |
12.3 years |
Beta decay |
|
Zinc (Zn) |
Zinc-65 |
243 days |
Beta decay |
|
Chlorine (Cl) |
Chlorine-36 |
301,000 years |
Beta decay |
|
Molybdenum-99 |
65.6 hours |
Beta decay |
|
|
Radon (Rn) |
Radon-220 |
55.6 seconds |
Alpha decay |
|
Iron (Fe) |
Iron-60 |
2.26 million years |
Alpha decay |
For more information, please check Stanford Advanced Materials (SAM).
Frequently Asked Questions
What factors influence the half-life of a radioisotope?
The half-life is determined by the nuclear properties of the radioisotope, including the forces within the nucleus that affect its stability.
Why is understanding half-life important in medicine?
It helps in determining the dosage and timing for treatments using radioisotopes, ensuring effectiveness while minimizing risks.
Can the half-life of a radioisotope be altered by external conditions?
No, the half-life is an intrinsic property and remains constant regardless of environmental factors.
How is half-life used in environmental science?
It aids in tracking the persistence and movement of radioactive contaminants in ecosystems over time.
What happens to a radioisotope after several half-lives have passed?
The quantity of the radioisotope decreases exponentially, becoming negligible after multiple half-lives.
