Halogens react with metals to produce metal halides through a process known as a redox reaction.

Halogens are a group of elements found in Group 7 of the Periodic Table. This group includes fluorine, chlorine, bromine, iodine, and astatine. These elements are characterized by their high reactivity, especially with metals. When a halogen interacts with a metal, a specific type of chemical reaction occurs, referred to as a redox reaction. In this type of reaction, one element is reduced (gaining electrons) while the other is oxidized (losing electrons).

In the interaction between halogens and metals, the metal undergoes oxidation while the halogen undergoes reduction. Metals are electropositive, meaning they tend to lose electrons and form positive ions, whereas halogens are electronegative and tend to gain these electrons to form negative ions. The result of this reaction is a compound known as a metal halide. Metal halides are typically ionic compounds, consisting of positively charged metal ions and negatively charged halide ions.

For instance, when sodium (a metal) reacts with chlorine (a halogen), the reaction can be represented as follows:

In this reaction, sodium is oxidized (losing an electron) to form sodium ions ($\text{Na}^+$), while chlorine is reduced (gaining an electron) to create chloride ions ($\text{Cl}^-$). These sodium ions and chloride ions then combine to form sodium chloride ($\text{NaCl}$), which is an example of a metal halide.

It’s important to note that the reactivity of halogens decreases as you move down the group. Fluorine, located at the top of Group 7, is the most reactive halogen and readily reacts with most metals. In contrast, astatine, situated at the bottom of the group, is the least reactive and does not react as easily with metals. This trend can be attributed to the increasing atomic size and decreasing electronegativity of the halogens as one descends the group.