Question

Is fluorine more reactive or less reactive than chlorine?

Answer 1

In chemistry, reactivity is a relatively nebulous term. It appears to encompass both thermodynamic and kinetic factors—that is, whether or not a material responds, as well as how quickly it reacts. Both components are separate, and they both rely on temperature in some way. For example, it is generally believed that the reactivity of group one metals (Na, K, etc.) rises as they progress down the periodic table, or that the reactivity of hydrogen is demonstrated by its interaction with oxygen.

Complete answer:
Electronegativity is the tendency of an atom in a molecule to draw the shared pair of electrons towards itself. Because it is simply a tendency, it is a dimensionless attribute. It simply denotes the net outcome of atoms' propensity to attract bond-forming electron pairs in various elements. On various scales, we quantify electronegativity. Linus Pauling created the most widely used scale. The most electronegative element is fluorine, which has a value of 4.0, while the least electronegative element is cesium, which has a value of 0.7.
When relative reactivity is uncertain, three factors must be considered: atomic radius, shielding, and the amount of electrons. The capacity of a halogen to acquire an electron is determined by the amount of electrons already present in the atom. Because chlorine has more electrons than fluorine, it repels a reactive electron with more force, making it less likely to react. Because fluorine contains fewer electron shells than chlorine, there are fewer electrons between the positive nucleus and the reactive electron, thus blocking or weakening the electromagnetic attraction. This is a form of protection.
Finally, fluorine is a considerably smaller molecule than chlorine, and the shorter distance between the nucleus and the electron, or radius, makes it more likely to attract and react with the electron, resulting in a noble gas configuration.
To sum up, the ${{F}_{2}}$ molecule has a low dissociation energy while the ${{F}^{-}}$ ion has a high hydration energy.
Fluorines electronegativity is higher than that of chlorine.

Note:
Fluorine is a chemical element with the atomic number 9 and the symbol F. It is the lightest halogen and occurs as an extremely poisonous, pale yellow diatomic gas under normal circumstances. It is very reactive being the most electronegative element, reacting with all other elements except argon, neon, and helium.