Cover -- Half Title -- Title Page -- Copyright Page -- Original Title Page -- Original Copyright Page -- Preface -- Preface to the Sencond Edition -- Table of Contents -- Chapter I Introduction: Atomic Theories: Earlier Views -- Chapter II Atomic Weights And Whole-Number Isotopes -- Chapter III Electrons and Atomic Nuclei: Sub-Atomic Phenomena -- Chapter IV Co-Ordinating the Electrical Properties of the Atom -- Chapter V K and L Series of Lines by X-Ray Analysis -- Chapter VI A Note On Crystal Structure -- Chapter VII Radio-Activity and Crystal Structure as Clues to Atomic Structure -- Chapter VIII Rutherford's Nuclear Theory of the Atom, with Detailed Experimental Evidence: Supplementary Notes -- Chapter IX The Quantum Theory -- Chapter X The Bohr-Rutherford Atom: Sommerfeld's Extension: And Epstein's Studies of the Stark Effect -- Chapter XI The Photo-Electric Effect -- Chapter XII The Zeeman Effect: Gaseous Ionisation: Ionisation Potentials: and Modern Views Concerning Radiation -- Chapter XIII The Lewis-Langmuir Atomic Theory: The Octet Theory: Introduction -- Chapter XIV The Lewis-Langmuir Atomic Theory: The Octet Theory: Arrangement of Electrons in Atoms and Molecules -- Chapter XV The Octet Theory: Being a Continuation from the Preceding Chapter: Ionisation in Solids and Liquids: Etc -- Chapter XVI Co-Ordinating the Rutherford and Lewis-Langmuir Theories -- Chapter XVII The Lewis-Langmuir Octet Theory of Valence Applied to Organic Nitrogen Compounds -- Chapter XVIII The Octet Theory as a Clue to Certain Types of Molecular Instability, and a Few Remarks -- Chapter XIX A Note of Caution -- Chapter XX The Possible Complexity of Hydrogen: Its Position in the Periodic Table.