What is radioactivity? Who discovered it? What do you mean by parent nuclide and daughter nuclide? What are the three basic radioactive decay processes, and how do they differ?

Radioactivity is the process by which unstable atomic nuclei release energy in the form of radiation to become more stable. This can occur spontaneously, and the radiation can include particles like alpha particles, beta particles, or electromagnetic radiation (gamma rays). The release of this energy is due to the breakdown of the nucleus of the atom.

Discovery of Radioactivity

Radioactivity was discovered in 1896 by the French physicist Henri Becquerel. He found that uranium salts emitted rays that could expose photographic plates. This discovery led to further investigations into the nature of radiation, and Marie Curie and Pierre Curie later expanded on his work, isolating new radioactive elements like radium and polonium.

Parent Nuclide and Daughter Nuclide

• Parent Nuclide: This is the unstable radioactive atom that undergoes decay. It is the original substance before it transforms into a more stable form.
• Daughter Nuclide: This is the stable or unstable atom that results from the decay of the parent nuclide. Depending on the decay process, it may itself be unstable and go through further decay.

The Three Basic Radioactive Decay Processes

Radioactive decay occurs through three primary processes:

1. Alpha Decay (α-decay):

   • Process: An unstable nucleus emits an alpha particle (two protons and two neutrons), which is essentially a helium nucleus.
   • Effect: The parent atom loses 2 protons and 2 neutrons, resulting in a decrease in atomic number by 2 and mass number by 4.
   • Example: Uranium-238 decays to thorium-234 by emitting an alpha particle.

   α-decay tends to occur in heavy elements (like uranium, radium) that have large nuclei, which makes them unstable and more likely to emit an alpha particle.

2. Beta Decay (β-decay):

   • Process: A neutron in an unstable nucleus transforms into a proton, emitting a beta particle (an electron) and an antineutrino.
   • Effect: The atomic number of the parent increases by 1 (since a neutron turns into a proton), but the mass number remains unchanged.
   • Example: In the beta decay of carbon-14, it decays into nitrogen-14 by emitting a beta particle.

   β-decay generally occurs in elements where the ratio of neutrons to protons is too high, causing the nucleus to decay by converting a neutron into a proton.

3. Gamma Decay (γ-decay):

   • Process: In this type of decay, the nucleus loses excess energy in the form of gamma rays (high-energy photons), without changing the number of protons or neutrons in the nucleus.
   • Effect: There is no change in the atomic number or mass number; only energy is released.
   • Example: After an alpha or beta decay, the daughter nucleus may still be in an excited state and release energy as gamma radiation to return to a more stable state.

   γ-decay typically follows other types of decay (like alpha or beta decay) when the resulting nucleus is still in an excited energy state and needs to release extra energy.

Differences Between the Three Decay Processes:

• Alpha Decay involves the emission of a heavy particle (alpha particle), which results in a reduction in both mass and atomic numbers.
• Beta Decay involves the transformation of a neutron into a proton and the emission of a beta particle (electron), leading to a change in the atomic number but no change in the mass number.
• Gamma Decay involves the release of energy in the form of gamma rays, without changing the composition of the nucleus in terms of protons or neutrons.

Each of these processes occurs when the nucleus is in an unstable configuration and aims to reach a more stable energy state.