Electronegativity of heavier elements of Group 15
electronegativity value decrease down the group but amongst the heavier elements difference is not that much pronounced.


The reason for this is that in heavier elements much more filling of inner d and f orbitals starts. For example as we move down from Sb to Bi, just 6 (3+3) more electrons fill p sub-shell, and 2 electrons enter to s sub-shell. Whereas on the other hand, 24 (10+14) electrons make their way to d and f sub-shell. This results in much poor shielding of electrons in outermost shell and effective nuclear charge thus remains approximately same in heavier elements. So, they have nearly same value of electronegativity on electronegativity scales.