A Principle Written in Diagrams: The Aufbau Principle for Molecules and Its Visual Representations, 1927–1932

摘要: Today the aufbau (building-up) principle is best known as a theoretical ground for electronic interpretation of periodic table. Proposed by Danish physicist Niels Bohr in early 1920s, was tool obtaining picture atomic constitution, i.e., arrangement electrons on orbits around nucleus. In practice, it meant imaginary process which were placed, one one, into energy levels prescribed orbits. denoted with two quantum numbers, principal and subordinate, limited number each orbit could accommodate, considering spectroscopic chemical properties elements. A few years later, advent mechanics, Pauli exclusion rationalized pairing building-up process, turned out that four not two, needed to describe state an atom. Finally, 1932, “orbits” renamed “orbitals” implying mathematically “one-electron wave functions,” afforded statistical motion, rather than its exact trajectory. The configuration (or structure) atoms then seemed give concrete mechanical basis rationalization table, however, does conceal semi-empirical origin principle. Historians have pointed Bohr’s research program had distinctively deductive inductive character, drawing both calculations empirical knowledge.1 Even when accurate orbital energies become available, rigor principle—e.g., assignment numbers particular electron explanation closing shells—is still question.2