Question

Which elements in the periodic table are most metallic and most electronegative?

Answer 1

Metallic character refers to the reactivity of a metal. Metals tend to lose electrons in chemical reactions, as indicated by their low ionization energies. Within a compound, metal atoms have a relatively low attraction for electrons, as indicated by their low electronegativities.
So, high electropositivity = best metallic character,
The most metallic element is francium. However, francium is a man-made element, except for one isotope, and all isotopes are so radioactive they almost instantly decay into another element. The natural element with the highest metallic character is therefore cesium.

Fluorine is the most electronegative element. Fluorine has an electronegativity of 3.98 on the Pauling Electronegativity Scale and a valence of 1.
A fluorine atom needs one electron to fill its outer electron shell and achieve stability, which is why free fluorine exists as the $F^{-}$ ion. Other highly electronegative elements are oxygen and chlorine.