Standard Form of the Periodic Table

Quantum Nanochemistry—Volume II Quantum Atoms and Periodicity 

The properties of the elements which depend on the atomic nucleus, present a linear variation, meaning that they are nonperiodic. These nonperiodic properties are  

The properties which depend on the external electronic shell stmcture vary periodically with the Z number. The most important periodic properties are the atomic radius, the atomic volume, the ionic radius, the ionic volume, the melting point, the boiling point, the ionization energy, the electron affinity, the electronegativity, the valence, the acid-base character etc. (Aldea et al., 2000). 

The remaining of this Volume will widely discuss about the electronegativity and related chemical periodic indices, as a starting point for (in principle) all other periodic properties of elements from the Periodic Table. 

The periodic law is not of the physical but the chemical kind, although not often properly realized. It resides in the fact of attributing four quantum numbers (principal, orbital, magnetic, and spin) to each electron in arranging them in the so-called configuration by the aujbau principle according which the Periodic Table is constructed. Certainly, such quantum labeling 

---

The standard form of the periodic table has also undergone some minor changes regarding the elements that mark the beginning of the third and fourth rows of the transition elements. Whereas older periodic tables show these elements to be lanthanum (57) and actinium (89), more recent experimental evidence and analysis have put lutetium (71) and lawrencium (103) in their former places. It is also interesting to note that some even older periodic tables based on macroscopic properties had anticipated these changes. 

---