Absolute Dimensions of Atoms

The electron energy (ionization potential) in Bohr s theory depends not only on Z but also on the effective principal quantum number n which characterizes the electron shell of an atom, 

There is no consensus about how to define atomic sizes. As a quantum object, the atom has no clear-cut boundary and no definite size electron density of an isolated atom drops to zero only at infinite distance. However, nearly all this electron density 

However, in structural chemistry it is more important to have the radii describing, however imperfectly, the outer boundary of atoms. Electronic polarizability, a, of an isolated atom is one of the size-related properties (see above), hence Nagle [100] defined its radius as r = Bohorquez and Boyd [90] derived atomic radii as 

Since isolated atoms are generated by dissociation of a chemical bond, their radii can be roughly estimated from the critical value of the interatomic distance on the verge of dissociation [101], using the universal equation of state (EOS) [102], 

Hence to disrupt a chemical bond, it must be stretched by a factor of 

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