Structure of the Atom and Nuclear Physics

Vocabulary flashcards covering key terms and definitions related to atomic structure and nuclear physics.

Structure of the Atom

A tiny nucleus containing protons and neutrons surrounded by electrons in energy levels.

Subatomic Particles

Proton +1 (1), Neutron 0 (1), Electron –1 (negligible).

Atomic Number

The number of protons in an atom.

Mass Number

The total number of protons and neutrons in an atom.

Isotopes

Atoms of the same element with the same number of protons but different numbers of neutrons.

Development of the Atomic Model

Progression from Plum pudding to Rutherford’s nuclear model, Bohr’s planetary model, and Chadwick’s discovery of neutrons.

Rutherford’s Experiment

Alpha particles fired at gold foil showed most passed through, but some deflected, indicating a small, dense, positively charged nucleus.

Bohr Model

Proposed that electrons orbit the nucleus at fixed energy levels or shells.

Electron Arrangement

Electrons fill the lowest energy levels first; each level can hold a fixed number of electrons.

Radioactive Decay

The spontaneous emission of radiation from an unstable atomic nucleus.

Types of Radiation

Three types are Alpha (α), Beta (β), and Gamma (γ).

Alpha Particle

Consists of 2 protons and 2 neutrons; has a +2 charge and is strongly ionising with low penetration.

Beta Particle

A high-speed electron emitted from the nucleus; has a –1 charge and is moderately ionising with medium penetration.

Gamma Radiation

An electromagnetic wave with no mass or charge; weakly ionising and has high penetration.

Nuclear Equations

Total atomic number and total mass number are conserved.

Half-Life

The time taken for the number of radioactive nuclei or the activity of a sample to halve.

Activity

The rate at which a source decays, measured in becquerels (Bq).

Contamination vs Irradiation

Contamination refers to radioactive material on/in an object; irradiation refers to exposure to radiation without contact.

Uses of Radiation

Examples include medical tracers (gamma), radiotherapy (gamma), and smoke detectors (alpha).

Dangers of Radiation

Ionising radiation can cause cell mutation or cancer by damaging DNA.

Background Radiation

Sources include cosmic rays, rocks, soil, radon gas, and medical/nuclear industry sources.

Fission

The splitting of a large nucleus into two smaller nuclei, releasing energy and neutrons.

Chain Reaction

Neutrons from fission cause more nuclei to split, releasing more neutrons and energy.

Fusion

The joining of two light nuclei to form a heavier nucleus, releasing energy.

Fusion vs Fission

Fusion joins nuclei and requires high temperatures, while fission splits nuclei and is used in reactors.