In this paper,valency is defined on basis of first-order de- nsity matrix elements.The valencies of H,C,N,O,F are calculated and compared by CNDO/2,MINDO/3,SINDO1 and ab initio (STO-3G) me- thod.The valencies and hybrid orbtals of Al_2Cl_6 and B_2H_6 are discussed. And ...
The elements of the bond order matrix are used with the average energy approximation and theoretical values for r-3 integrals to obtain relative shielding constants for the fluorine nuclei. The assumption made by other workers that the -electron terms are effectively constant for the fluorobenzenes ...
The concept of valency which we built our example upon, is introduced in the very beginning of learning chemistry, as students first encounter different formulas of substances. Students are to compose some compound formulas themselves based on the valency values of a given pair of elements, so th...