Atoms and electrons

"Atoms and electrons" by J. W. N. Sullivan is a popular science treatise written in the early 20th century. It explains how experiments and theory uncover the structure of matter—atoms, electrons, and nuclei—through chemistry, electricity, radioactivity, and spectroscopy, and points toward relativity and the emerging quantum view. The aim is to give intelligent readers a concise, authoritative grasp of how modern physics understands the architecture of matter. The opening of this work sets out the groundwork of measurement—dimensions, the C.G.S. metric system, electrical unit systems, and scientific notation—then introduces Dalton’s atomic theory, the laws of definite and multiple proportions, and Avogadro’s hypothesis for fixing relative atomic weights. It uses thin films, diffusion, the kinetic theory of gases, and Einstein–Perrin’s Brownian motion to give tangible evidence of molecules. The text then presents electrons via cathode rays and ionization measurements, argues that their mass is electromagnetic in character, and interprets radioactivity as atomic disintegration into α, β, and γ emissions. From there it outlines Rutherford’s nuclear atom, the periodic system organized by atomic number, the reality of isotopes (chemically identical atoms of different mass), and how α and β decay move elements through the table; relativity’s mass–energy ideas and nuclear binding (the helium mass defect) are incorporated.

Atoms and electrons, by J. W. N. Sullivan. Republished by OpenStories from Project Gutenberg eBook #77675.