Abstract: The traditional explanation on the effect of lone pair bond weakening, as the result of inter-electronic repulsions between lone pair electrons on bonding atoms, become void when we compare bond energies of the hydrogen halides, because there are certainly no lone pair electrons on the hydrogen atom to repel the lone pair electrons of the fluorine.In this paper, the reasonable explanation on the effects of lone pair bond weakening by using graphic method of bond parameters is presented.It is considered that the weakening effect is a prime shielding result of lone pair electrons intervening between the bonding electrons and nucleus, rather than the interelectronic repulsions between lone pair electrons on separate atoms.

Key words: Lone pair electrons, Effects of the bond weakening, Shielding effect