List of Radioactive Elements with Symbols and Atomic Numbers
Understanding radioactive elements is essential in chemistry and helps students connect real-world examples like nuclear energy, medical scans, and even glowing materials to atomic theory. This topic makes radioactivity simple for exams and everyday understanding.
What is Radioactive Element in Chemistry?
A radioactive element is a chemical element with an unstable atomic nucleus that loses energy by emitting radiation (alpha, beta, or gamma rays). This concept appears in chapters related to Periodic Table trends, isotopes, and nuclear chemistry, making it a foundational part of your chemistry syllabus.
Radioactive Elements List with Symbols
Radioactive elements are found in both natural and synthetic forms. Below is a table listing common radioactive elements, their atomic numbers, symbols, and type.
| Element Name | Symbol | Atomic Number | State |
|---|---|---|---|
| Uranium | U | 92 | Natural |
| Thorium | Th | 90 | Natural |
| Radium | Ra | 88 | Natural |
| Radon | Rn | 86 | Natural |
| Polonium | Po | 84 | Natural |
| Plutonium | Pu | 94 | Synthetic |
| Americium | Am | 95 | Synthetic |
| Francium | Fr | 87 | Natural (Rare) |
| Actinium | Ac | 89 | Natural |
| Neptunium | Np | 93 | Synthetic |
Classification: Natural vs. Synthetic Radioactive Elements
Radioactive elements can be classified into two types:
- Natural radioactive elements: Found in the Earth's crust and atmosphere. Examples: Uranium (U), Thorium (Th), Radium (Ra), Polonium (Po).
- Synthetic radioactive elements: Man-made in laboratories using nuclear reactions. Examples: Plutonium (Pu), Americium (Am), Neptunium (Np).
Most radioactive elements are located after atomic number 82 (lead) in the periodic table.
Properties and Characteristics of Radioactive Elements
- Have unstable nuclei that spontaneously break down emitting alpha (α), beta (β), or gamma (γ) radiation.
- Each element has a characteristic half-life, which is the time it takes for half of the sample to decay.
- Some, like radium, can glow in the dark, but most do not.
- Can be harmful to living things due to ionising radiation, which can damage DNA and cells.
- Undergo transformations into different elements as they decay—a process called radioactive decay.
Uses of Radioactive Elements in Real Life
Radioactive elements have important roles in science, medicine, and industry:
- Medicine: Cobalt-60 treats cancer; Iodine-131 checks thyroid.
- Power Generation: Uranium-235 and Plutonium-239 fuel nuclear reactors.
- Industry: Americium-241 is found in smoke detectors.
- Radiometric Dating: Carbon-14 is used for dating old artefacts.
These examples show how radioactive elements connect science with our daily life and technology.
Relation with Other Chemistry Concepts
Radioactive elements are closely related to isotopes, nuclear reactions, and chemical element stability. They also help students understand radioactive decay and the concept of half-life.
Step-by-Step Example: Alpha Decay of Uranium-238
1. Start with Uranium-238’s radioactive nucleus.2. The unstable nucleus emits an alpha (α) particle (2 protons + 2 neutrons).
3. New element formed: Thorium-234.
Final equation:
²³⁸U₉₂ → ²³⁴Th₉₀ + ⁴He₂
Lab or Experimental Tips
Always handle radioactive materials using safety gear and radiation monitoring devices. Vedantu educators recommend using simulated experiments or digital counters to visualize decay and detect emitted particles in school labs.
Try This Yourself
- Find at least three radioactive elements on the periodic table.
- Identify their state (natural or synthetic) and one common use for each.
- Explain why Uranium-235 is used in nuclear power plants.
Final Wrap-Up
We explored radioactive elements—their definitions, list, properties, decay process, uses, and modern-day relevance. For more detailed explanations and class notes, explore Vedantu’s chemistry resources and join live sessions for expert guidance.
Actinides
FAQs on What Are Radioactive Elements?
1. What are radioactive elements?
Radioactive elements are chemical elements with unstable nuclei that spontaneously emit radiation as they undergo radioactive decay.
• These elements change into other elements or isotopes over time.
• Examples include uranium (U), thorium (Th), and radium (Ra).
• They are important for medical treatments, research, and nuclear power.
2. Which elements are naturally radioactive?
The main naturally radioactive elements include:
• Uranium (U)
• Thorium (Th)
• Radium (Ra)
• Polonium (Po)
These elements have unstable nuclei and emit radiation without any artificial induction.
3. How do radioactive elements occur in the periodic table?
Radioactive elements are found mainly among:
• Heavy elements with atomic numbers greater than 82 (lead)
• Actinide series (atomic numbers 89–103)
• Some transition and post-transition metals
They can be identified by their symbols and atomic numbers on the periodic table.
4. What is the difference between natural and synthetic radioactive elements?
Natural radioactive elements occur in nature and decay spontaneously (e.g., uranium, thorium).
Synthetic radioactive elements are created in laboratories or reactors by nuclear reactions (e.g., technetium, einsteinium).
• Natural: Found in Earth's crust
• Synthetic: Created and not commonly found in nature
5. What is the half-life of a radioactive element?
The half-life is the time required for half of the atoms in a radioactive sample to decay.
• Half-life values vary widely for different elements.
• Example: Uranium-238 has a half-life of about 4.5 billion years.
• Half-life determines the stability and persistence of radioactive elements.
6. What are the uses of radioactive elements?
Radioactive elements are used in:
• Medicine: Cancer treatment (radiotherapy), diagnostics (imaging)
• Industry: Nondestructive testing, radiography
• Scientific research: Radioactive tracers, dating rocks and fossils
• Energy: Generating electricity in nuclear reactors
7. Do all radioactive elements glow in the dark?
No, only a few like radium naturally glow due to their radiation interacting with surrounding materials.
Most radioactive elements do not produce visible light unless they are mixed with phosphors or other substances that fluoresce.
8. What are some health and environmental risks of radioactive elements?
Radioactive elements can be dangerous due to their ionizing radiation, which can:
• Damage living cells
• Cause cancers or mutations
• Contaminate air, water, and soil
Proper handling, storage, and disposal are essential for safety.
9. How are radioactive elements detected?
Detection methods include:
• Geiger-Muller counters: Measure ionizing radiation
• Scintillation counters: Detect flashes of light from radiation
• Film badges: Monitor radiation exposure over time
These instruments help scientists and workers stay safe while handling radioactive materials.
10. Why do some elements become radioactive?
Radioactivity occurs when an element's nucleus is unstable due to excess protons or neutrons.
• These nuclei emit energy as they transform into stable forms.
• Usually, heavy elements with large, complex nuclei are naturally unstable and radioactive.
11. Can radioactive elements occur in biological systems?
Yes, trace amounts of some radioactive isotopes like potassium-40 and carbon-14 are naturally present in living organisms.
These help in metabolic processes and are used for radiocarbon dating in biology and archaeology.
12. How are synthetic radioactive elements produced?
Synthetic radioactive elements are created by bombarding stable elements with particles in nuclear reactors or particle accelerators.
This process changes the number of protons or neutrons in the nucleus, forming new unstable atoms that emit radiation.
