How does shielding affect electronegativity?

1 Answer
Oct 25, 2015

The more shielding, the lower electronegativity.


I think I'll explain with an example.

Fluorine (F) has the highest electronegativity on the whole periodic table with a score of 4.0.

This is because its nucleus has a very powerful attractive (effective nuclear charge) force directed towards all of its electrons. All of the electron levels are pulled very close to the nucleus, so there is very little shielding between the nucleus and the electrons.

Compare this to Francium, the element with the lowest electronegativity, weighing in at 0.7.

Francium is at the very bottom of the first group. This means that it has a LOT of electron levels it has to hold onto compared to fluorine. Therefore, there are more levels causing shielding between the electrons and the positively charged nucleus.

More on Effective Nuclear Charge!