Radioactivity: Structure of Atom

Structure of an Atom

An atom consists of a dense, central nucleus, surrounded by negatively charged electrons.

The nucleus is made up of positively charged protons and neutral neutrons. Protons and neutrons both have a similar mass and are referred to as nucleons.
Electrons are tiny particles that orbit the nucleus in electron shells. They have a negative charge and negligible mass.

The atomic number, often denoted by Z, is the number of protons in the nucleus and defines the type of atom, or its atomic species (e.g., carbon, oxygen).
The mass number (A) is the total number of protons (Z) and neutrons (N) in the nucleus.

Isotopes are atoms of the same element (i.e., same atomic number) but with a different number of neutrons, and hence differing mass numbers. While their chemical properties stay the same, their nuclear properties may differ, making some isotopes radioactive.

Radioactivity is the process in which unstable atomic nuclei decay over time, releasing particles or electromagnetic radiation.

The three types of radiation emitted during radioactive decay are: alpha (α), beta (β), and gamma (γ) radiation.
Alpha decay happens when an atom ejects 2 protons and 2 neutrons. This large, positively charged particle has the most ionising power but is easily stopped by a sheet of paper or air.
Beta decay occurs when a neutron in the nucleus decays into a proton, releasing an electron (beta particle) and an antineutrino. It has lesser ionising power than an alpha particle but is more penetrating.
Gamma radiation represents the emission of high-energy photons. It’s the most penetrating type of radiation, but it has no charge and doesn’t alter the atomic number or mass number.

Half-life is the time it takes for half the number of unstable atoms in a sample to decay. It’s an important measure when dealing with radioactive materials.

By understanding the structure of atoms and the nature of radioactive decay, it’ll be easier to grasp the more complex topics in this subject area.