Answer:
The most vigorous reaction, between two elements for the formation of an ionic compound, in theory, would be between the most electronegative element and the least electronegative element, Fluorine and Francium respectively, according to the Pauling scale. So it would be 2Fr + F2 ->2FrF. But for a more practically reasonable choice, because Francium has a very short half-life, would be Caesium and Fluorine because Caesium is just right above Francium, being in the same group (Group 1 / IA). 2Cs + F2 -> 2CsF. In both cases, the outermost electron of the Caesium/Francium atom will be taken by the Fluorine atom, in the process, releasing a massive amount of energy.
Step-by-step explanation:
Although chemical reactions can involve any of the other hundred-plus elements on the periodic table, it turns out that most of the familiar energy-releasing reactions involve only hydrogen, carbon, and oxygen. Consider again the reaction, which involves only hydrogen and oxygen atoms. Metals often react with nonmetals to form ionic compounds. These compounds are composed of positive and negative ions formed by adding or subtracting electrons from neutral atoms and molecules. Nonmetals combine with each other to form covalent compounds, which exist as neutral molecules.