Some people like to use an arrow, and the arrow points in the direction of the more electronegative end.
In all, the nitrogen and carbon ligands, to be effective, require linkage to other electronegative centers.
Because of the high electronegativity of the positively charged noble-gas centers, any ligands for those centers must themselves be electronegative.
Lead dioxide, on the other hand, is highly electronegative, preferring to absorb electrons in chemical reactions.
And you see where the most electronegative elements are, and fluorine is the most electronegative of the active elements.
