Why Fluorine is the most electronegative and reactive of all the elements in the periodic table?

Fluorine is the most electronegative and reactive of all the elements in the periodic table, due to a combination of factors:

• Atomic Structure: Fluorine has the highest effective nuclear charge of any element since it has only one filled electron shell (1s2 2s2 2p5). This allows the nucleus to exert strong attraction on the valence electrons in the outer 2p orbitals, causing them to be tightly bound.
• Small Atomic Radius: Fluorine has a very small atomic radius (due to contraction after filling the inner electron shells), meaning valence electrons on separate atoms can get very close to each other. This enhances intermolecular interactions and reactivity.
• Lone Pairs: Fluorine tends to have lone pairs of non-bonding valence electrons that can also enhance reactivity through hydrogen bonds or Van der Waals forces.
• Bond Energy: The combination of strong effective nuclear charge and lone pairs leads fluorine compounds to have very high bond energies. Breaking these bonds releases a lot of energy to power chemical reactions.
• Oxidizing Ability: The high electronegativity makes fluorine very electron-hungry. It has the strongest oxidizing ability among all elements, readily accepting electrons in chemical bonds and reactions.

These factors together make fluorine the most reactive halogen and most electronegative element. Its small size and lone pairs facilitate formation of strong polarized bonds, enabling fast energetic reactions across the periodic table. When handling fluorine for industrial or laboratory use, extreme care is required due to its energetic reactivity with both organic and inorganic substances.