Atomic Structure, Isotopes, and Radioactivity Explained

Atomic Structure and Composition

All atoms contain one or more negatively charged particles called electrons. Every atom belongs to a specific chemical element. To represent them, we use the symbol _Z^AX, where Z indicates the atomic number (number of protons) and A is the mass number (the sum of protons and neutrons).

Isotopes and Ions

• Isotopes: Atoms that have the same number of protons but a different number of neutrons.
• Ions: Atoms often gain or lose electrons when combining with other elements.
  • When an atom loses electrons, it acquires a positive charge and becomes a cation.
  • When an atom gains electrons, it acquires a negative charge and becomes an anion.

Radioactivity and Nuclear Processes

Radioactivity involves the loss of particles from an unstable nucleus:

• Nuclear Fission: The breaking of a nucleus to form smaller nuclei.
• Nuclear Fusion: The union of two atomic nuclei to form a larger nucleus.

When atoms undergo these processes, they transform into different chemical elements. Radiation types include:

• Alpha (α): Low penetration power.
• Beta (β): Average penetration power.
• Gamma (γ): High penetration power.

Radioactive waste is highly dangerous; small amounts can emit radiation harmful to human health, and some remain radioactive for thousands of years.

Atomic Models

• Thomson: Proposed the "raisin pudding" model, where electrons are embedded in a large mass of positive charge.
• Rutherford: Determined that the atom consists of a small, dense, positively charged nucleus with electrons orbiting in the crust.
• Bohr: Established that electrons revolve around the nucleus in specific circular orbits called energy levels.

Applications of Radioactive Isotopes

• Energy: Nuclear power plants using uranium and plutonium.
• Research: Scientific experiments, dating findings, and verifying artworks.
• Industry: Chemical markers and forensic investigations.
• Medicine: Diagnostic methods and radiotherapy.

Note: Adding or subtracting electrons only changes the ion charge; the number of protons and neutrons remains constant.