For 10 points, name this most electronegative element and lightest halogen.
Niobium is typically separated from tantalum by complexing it with this element. Ruppert's reagent can be used to add a functional group containing carbon and this element to carbonyls. One of the most commonly studied ionic liquids includes a weakly-coordinating anion consisting of this element and boron. An anti-metabolite cancer drug that inhibits thyÂ·midÂ·ylÂ·ate synthase consists of this element bonded to the 送ve position of uracil. A molecule with this an atom of this element at its center exhibits the strongest known hydrogen bonds. The isotope of this element with atomic weight nineteen is NMR-active. The strongest superÂ·acid consists of antimony and this element, which causes the strongest inductive e鴁fect when added to the alpha position of acetic acid. For 10 points, name this most electronegative element and lightest halogen.
Niobium is typically separated from tantalum by complexing it with this element.
Fluorine [or F]