Nuclear transmutation refers to the process in which an atomic nucleus changes from one element or isotope to another due to a nuclear reaction. This can occur either naturally, as a result of radioactive decay, or artificially, through a controlled process like bombarding the nucleus with particles.
Nuclear decay is a specific type of nuclear transmutation, where an unstable atomic nucleus transforms into a more stable one by emitting radiation. This can happen spontaneously over time in naturally occurring radioactive elements.
Three Basic Radioactive Decay Processes and How They Differ
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Alpha Decay (α-decay):
- Process: In alpha decay, the parent atom releases an alpha particle, which consists of 2 protons and 2 neutrons (essentially a helium nucleus). This results in a decrease in both the atomic number (by 2) and the mass number (by 4) of the original atom.
- Effect: The parent atom transforms into a new element that is 2 places earlier in the periodic table.
- Example: Uranium-238 (U-238) undergoes alpha decay to become thorium-234 (Th-234).
- Equation:
U-238→Th-234+Alpha particle
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Beta Decay (β-decay):
- Process: In beta decay, a neutron in the nucleus of an unstable atom is converted into a proton, and a beta particle (an electron) is emitted from the nucleus. This results in an increase in the atomic number by 1, while the mass number remains unchanged.
- Effect: The parent atom changes into a new element with the same mass number but a different atomic number.
- Example: Carbon-14 (C-14) undergoes beta decay to become nitrogen-14 (N-14).
- Equation:
C-14→N-14+β−
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Gamma Decay (γ-decay):
- Process: Gamma decay involves the emission of high-energy electromagnetic radiation (gamma rays) from an excited nucleus. No change occurs in the number of protons or neutrons, meaning the atomic number and mass number stay the same. The emission of gamma rays helps the nucleus move to a lower energy state.
- Effect: Gamma decay does not change the identity of the element, but it helps the nucleus become more stable by releasing excess energy.
- Example: After uranium-238 undergoes alpha decay, the daughter nucleus thorium-234 may emit gamma radiation as it reaches a more stable state.
- Equation:
Th-234 (excited state)→Th-234+γ
How They Differ:
- Alpha Decay results in the emission of a particle that leads to a decrease in both the atomic number and mass number.
- Beta Decay involves the conversion of a neutron into a proton, resulting in an increase in the atomic number but no change in the mass number.
- Gamma Decay is the release of electromagnetic radiation, and it does not alter the atomic or mass numbers of the nucleus but reduces its energy.