Classical physics Electronegativity

The periodic structure of the elements is evident for many physical and chemical properties, including chemical valence, atomic radius, electronegativity, melting point, density, and hardness. Two classic prototypes for periodic behavior are the variations of the first ionization energy and the atomic radius with atomic number. These are plotted in Figs. 9.4 and 9.5. 

From the birthday of the modem chemistry, i.e., since Boyle had used for the first time a coherent atomic theory in science in his 1661 famous book The Skeptical Chymist, the fundamental principles and concepts of matter stmcture were constantly shared by the physics and chemistry. However, the divorce of chemistry from physics would have to come with many occasions by means of classical chemical concepts, e g., valence, chemical bond, and electronegativity. The mystery by which the atoms are kept together and still preserving their intimate properties was searched by great minds, from Newton to Lewis, being the key furnished only with the advent of quantum theory. Within this new paradigm of matter there is the feeling that the physics and chemistry are united under the actual common... 

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