Atomic Structure: Protons, Neutrons, and Electrons

Atomic Structure and Nuclear Reactions

1. Atomic Components: Protons, Neutrons, and Electrons

Protons, possessing positive charges, reside within the nucleus. Negatively charged electrons revolve around the nucleus. Electrons must orbit to avoid being drawn into the nucleus. However, a question remained: how do protons, all with the same positive charge, remain together in the nucleus without repelling each other? There must be something more, leading to the postulation of neutrons.

2. Mass Defect and Binding Energy

The mass difference is explained by the binding energy between nucleons (protons and neutrons). According to the theory of relativity, any energy corresponds to a mass, which explains the mass defect.

3. Types of Radiation: Alpha, Beta, and Gamma

• Alpha: Positively charged particle streams consisting of two neutrons and two protons (helium nuclei). They are deflected by electric and magnetic fields. Although very energetic, they have low penetrating power.
• Beta: Streams of electrons (negative beta) or positrons (positive beta) resulting from the decay of neutrons or protons in an excited nucleus. They are deflected by magnetic fields and are more penetrating than alpha particles, but with lower ionization power.
• Gamma: Electromagnetic waves. This is the most penetrating type of radiation. These short-wavelength electromagnetic waves require very thick layers of lead or concrete to be stopped.

4. Half-Life and Lifetime

Half-life is the time required for half the nuclei of an initial sample of a radioactive substance to disintegrate.

Lifetime is the average lifespan of a nucleus before it disintegrates.

5. Radioactive Decay Rate

Reactive activity, also known as the decay rate of a radioactive sample, is the number of atomic nuclei in a given quantity of the sample that decays per second.

6. Nuclear Fission vs. Nuclear Fusion

While nuclear fission releases energy by splitting atomic nuclei, nuclear fusion releases energy when two nuclei combine to form a new atom.

While the nuclear fission process is well-understood and manageable, nuclear fusion presents challenges in confinement, requiring further research. Significant progress is being made, thanks to projects like ITER.

The fusion reaction generates approximately four times more energy than the fission reaction. Fusion also produces less pollution than fission, eliminating the danger of radioactive waste.