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Published: Kem. Ind. 70 (9-10) (2021) 581–587
Paper reference number: KUI-19/2021
Paper type: Professional paper / Chemistry in Teaching
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How to Define the Size of an Atom

N. Raos


Despite the fact that atomic, i.e. Van der Waals, ionic, and covalent radii are commonplace in chemical textbooks, their real, quantum-mechanical nature is blurred by simplified scholar definitions. The size of an atom may be defined, and calculated, in many ways (from atomic orbital density, bond lengths, microwave spectra, virial coefficient, Lennard-Jones potential), but whatever is calculated, or defined, the obtained value cannot be properly compared to the size of a macroscopic object. This paper stresses the need that students understand the real nature of quantum-chemical models, and not confuse various representations of molecular structure (molecular models) with the real atoms and molecules.

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teaching chemistry, quantum chemistry, atomic models, covalent radius, Van der Waals radius, bond length