What term refers to how strongly an atom of an element attracts electrons in a chemical bond with an atom of a different element?
You refer to
Elements towards the right of the Periodic Table as we face it, with high nuclear charges, e.g. oxygen, fluorine, tend to have high electronegativities. Why? Because the high nuclear charge acts on the valence electrons, contracting the valence shell. When a Period is filled on the Periodic Table, electrons add to the next shell, and valence electrons are somewhat shielded from the increased nuclear charge.
When we look at molecules which combine strongly electronegative elements with moderately electronegative elements, such as