Why is fluorine considered the most reactive chemical element?

Fluorine is considered the most reactive chemical element due to a combination of its unique atomic structure and thermodynamic properties. Its extreme reactivity is primarily attributed to the following factors:1

• Highest Electronegativity: Fluorine possesses the highest electronegativity of all elements, meaning it has an unparalleled ability to attract electrons to itself when forming chemical bonds.23
• Small Atomic Size: The small size of the fluorine atom allows it to approach other atoms closely, facilitating the formation of strong, stable bonds with essentially all other elements.213
• Low Dissociation Energy: The bond energy required to break the F–F bond in diatomic fluorine ($F_2$) is relatively low. This weakness, caused by the small size of the atoms leading to increased repulsion between nonbonding orbitals, makes it easier for fluorine to react.34
• High Oxidizing Power: Because of its high electron affinity and the strength of the bonds it forms with other elements, fluorine acts as the most powerful oxidizing agent.23

These properties collectively result in a large heat of reaction when fluorine combines with other substances, rendering it highly reactive.3