原子的有效成键半径和键长经验公式以及对某些地球化学问题的讨论

EFFECTIVE BONDED RADII OF ATOMS AND AN EMPIRICAL EQUATION OF BOND LENGTHS——A DISCUSSION ON SOME RELATED PROBLEMS IN GEOCHEMISTRY

Experimental studies have shown that the effective radii of atoms and ions in crystals and molecules are variable. The bonded radii of atoms depend upon their structure and environment, especially upon the bond type. The bond length of a ehemical bond is equal to the sum of the effective bonded radii of bonded atoms:

Experimental studies have shown that the effective radii of atoms and ions in crystals and molecules are variable. The bonded radii of atoms depend upon their structure and environment, especially upon the bond type. The bond length of a chemical bond is equal to the sum of the effective bonded radii of bonded atoms:Based on the experimental facts and the explanation provided by quantum chemistry, an empirical equation has been developed to calculate the effective bonded radii of atoms:where k is bond type parameter (bond ionic character i or covalent character k); r+A and r-B are standard ionic radii; r0A and r0B are covalent radii. It follows that the bond length equation of a chemical bond is:orIn the above awo equations, when k = 0 (standard ionic bonding), i.e. the bond length is equal to the sum of ionic radii; when i = 0 (standard covalent bonding), the bond length is equal to the sum of covalent radii. Using the above equations the bond lengths of 176 binary inorganic crystals with intermediate bond type have been calculated and the results are in good agreement with experimental values.Some related problems in geochemistry are also discussed in terms of the concept of effective bonded radii of atoms, and the emperical equation of bond lengths.