“…Based on the results of several previous studies 12 28 51 52 53 54 , 26 structural parameters characterizing various physical and chemical properties of the metal ions were investigated. They include AN 12 , AW 28 52 , AR 28 52 53 55 , CR 51 52 53 , r 12 28 52 53 , melting point ( MP ) 52 , density ( D ) 52 , enthalpy (heat) of vaporization ( Eh ) 52 , boiling point ( BP ) 52 , difference in ionization potentials between the ion oxidation numbers OX and OX −1 (Δ IP(eV) ) 12 28 54 , electrochemical potential (∆ E 0 (V) ) 12 28 52 54 , log of first hydrolysis constant ( |logK OH | ) 12 , covalent index ( X m 2 r ) 12 24 , polarization force parameters ( Z/r,Z/r 2 and Z 2 /r ) 12 24 , σp 12 , ionization potential ( IP ) 12 23 24 26 , electronegativity ( X m ) 12 23 24 , AN/∆IP 12 23 24 26 , AR/AW 23 24 , electronegativity index ( x ) 12 23 , relative softness ( Z/rx ) (x is a electronegativity value index) 12 23 24 , similar polarization force parameters ( Z/AR and Z/AR 2 ) …”