Resources | Subject Notes | Physics
State that during α-decay or β-decay, the nucleus changes to that of a different element.
Radioactive decay is a spontaneous process in which an unstable atomic nucleus loses energy by emitting particles or electromagnetic radiation. This process results in the transformation of the original nucleus into a different element or a different isotope of the same element.
In alpha decay, the nucleus emits an alpha particle, which is a helium nucleus ($^{4}_{2}He$).
When a nucleus undergoes alpha decay, its atomic number (number of protons) decreases by 2 and its mass number (number of protons and neutrons) decreases by 4.
This change in the number of protons means that the element is transformed into a different element.
Example: Uranium-238 ($^{238}_{92}U$) decays into Thorium-234 ($^{234}_{90}Th$) by emitting an alpha particle.
In beta decay, a neutron in the nucleus is converted into a proton, emitting an electron (beta particle, $^{-}e$) and an antineutrino.
When a nucleus undergoes beta decay, its atomic number increases by 1 and its mass number remains the same.
The conversion of a neutron into a proton means that the element is transformed into a different element.
Example: Carbon-14 ($^{14}_{6}C$) decays into Nitrogen-14 ($^{14}_{7}N$) by emitting a beta particle.
During both alpha decay and beta decay, the nucleus undergoes a transformation, resulting in a change in the element's identity. This is because the number of protons in the nucleus changes during these processes.
| Decay Type | Change in Atomic Number | Change in Mass Number | Emitted Particle | Example |
|---|---|---|---|---|
| Alpha Decay (α) | -2 | -4 | $^{4}_{2}He$ (Helium nucleus) | $^{238}_{92}U \rightarrow ^{234}_{90}Th + ^{4}_{2}He$ |
| Beta Decay (β) | +1 | 0 | $^{-}e$ (Electron) and antineutrino | $^{14}_{6}C \rightarrow ^{14}_{7}N + $ (electron and antineutrino) |