The Dual Sense of the Term 'Element,' Attempts to Derive the Madelung Rule, and the Optimal Form of the Periodic Table, If Any

摘要

This article concerns various foundational aspects of the periodic system of the elements. These issues include the dual nature of the concept of an "element" to include element as a "basic substance" and as a "simple substance." We will discuss the question of whether there is an optimal form of the periodic table, including whether the left-step table fulfils this role. We will also discuss the derivation or explanation of the [n + l, n] or Madelung rule for electron-shell filling and whether indeed it is important to attempt to derive this rule from first principles. In particular, we examine the views of two chemists, Henry Bent and Eugen Schwarz, who have independently addressed many of these issues. (C) 2008 Wiley Periodicals, Inc. Int J Quantum Chem 109: 959-971, 2009