[Radiologic Physics] Ep 2 – Atomic Structure

This episode examines the structure of the atom and its direct relevance to radiologic science. Beginning with a survey of atomic theory from early Greek philosophy through Thomson, Rutherford, Bohr, and the modern quantum mechanical model, the episode defines the atom as the smallest unit of a chemical element and identifies its two main regions: the nucleus and the electron shells. Subatomic particles — protons, neutrons, and electrons — are described in terms of charge, mass in atomic mass units, and location within the atom. Atomic number (Z) and atomic mass (A) are defined and distinguished, with emphasis on how the proton number determines elemental identity.Electron shell organization is then covered in detail, including shell symbols (K through Q), the shell capacity formula (2n²), the octet rule, binding energy, and the balance of centripetal and centrifugal forces maintaining orbital stability. The periodic table is introduced through Mendeleev's and Moseley's contributions, with periods, groups, valence, and transition elements explained. The episode concludes with molecular and compound formation, and the two primary types of atomic bonding — ionic and covalent — with examples drawn from biologically and radiologically relevant molecules.Content is structured to support radiologic technology programs preparing for imaging coursework and ARRT certification review. This episode aligns with the Safety content category — Radiation Physics and Radiobiology subcategory — of the ARRT Radiography Examination Content Specifications.Audio content is adapted from original instructional material developed by Professor Sanjay Arya, M.S., R.T.(R)(MR) for radiologic technology education. Part of the Radiologic Physics series — Quantum Imaging Lab.© 2026 Quantum Imaging Lab. All rights reserved.