Radioactivity and Nuclear Processes
Key Terms in Radioactivity
- Alpha Particle: A helium nucleus emitted by some radioactive substances.
- Band of Stability: A band containing nonradioactive nuclides in a plot of the number of neutrons versus the atomic number.
- Beta Particle: A fast-moving electron emitted by the radioactive decay of substances.
- Carbon Dating: The determination of the age or date of organic matter from the relative proportions of the carbon isotopes it contains.
- Chain Reaction: A process in which the products themselves promote or spread the reaction, which under certain conditions may accelerate dramatically.
- Critical Mass: The minimum amount of fissile material needed to maintain a nuclear chain reaction.
- Fission: The action of dividing or splitting something into two or more parts.
- Fusion: The process or result of joining two or more things together to form a single entity.
- Gamma Ray: Penetrating electromagnetic radiation arising from the radioactive decay of atomic nuclei.
- Half-life: The time taken for the radioactivity of a specified isotope to fall to half of its original value.
- Ionizing Radiation: Radiation consisting of particles, X-rays, or gamma rays with sufficient energy to cause ionization.
- Nuclear Force: A strong attractive force between nucleons in the atomic nucleus that holds the nucleus together.
- Nucleon: A proton or a neutron.
- Nuclide: A distinct kind of atom or nucleus characterized by a specific number of protons and neutrons.
- Positron: A subatomic particle with the same mass as an electron and a numerically equal but positive charge.
- Radiation: The emission of energy as electromagnetic waves or as moving subatomic particles.
- Radioactive Dating: Any method of determining the age of earth materials or objects of organic origin based on measurement.
- Radioactive Decay: The spontaneous transformation of an unstable atomic nucleus into a lighter one, in which radiation is released in the form of alpha particles, beta particles, gamma rays, and other particles.
- Radioisotope: A radioactive isotope.
- Transmutation: The changing of one element into another by radioactive decay, nuclear bombardment, or similar processes.
- Transuranium Elements: The chemical elements with atomic numbers greater than 92 (all are radioactive).
Radioactive Decay Processes
How does an unstable nucleus release energy?
An unstable nucleus releases energy by emitting radiation during the process of radioactive decay.
Changes During Alpha Decay
During alpha decay, the mass number decreases by 4, and the atomic number decreases by 2.
Changes During Beta Decay
During beta decay, the mass number does not change, and the atomic number increases by 1 because a neutron is converted into a proton.
Changes During Gamma Emission
Gamma emission does not change the number of protons and neutrons, but it does change the way they are arranged.
Penetrating Power of Particles
Penetration levels:
- Alpha is the least penetrating (stopped by paper).
- Beta is in the middle (stopped by wood).
- Gamma is the most penetrating (stopped by lead or concrete).
Natural vs. Artificial Transmutation
Natural radioactive decay occurs due to radioactive components found in nature. Artificial transmutation is the changing of a nucleus through nuclear reactors and accelerators.
Nuclear Fission vs. Nuclear Fusion
Fission is the splitting of a heavy, unstable nucleus into two or more lighter nuclei, while fusion is the process where two light nuclei combine together, releasing vast amounts of energy.
Why is fusion not used for electricity?
Fusion reactions occur only at very high temperatures. No known materials can withstand such temperatures, so there is no way to harness nuclear fusion for energy production.