Halogens

Halogens are a group of five nonmetallic elements – fluorine, chlorine, bromine, iodine, and astatine – belonging to Group 17. Elemental halogens exist as diatomic molecules. 

At room temperature, fluorine and chlorine are gases, bromine is a liquid, and iodine is a solid. Less is known about the properties of the fifth element, astatine, which is a rare and highly radioactive solid. 

The physical properties of halogens, such as elemental color, vary moving down the group. Atomic radii increase with increasing atomic number, and the melting point and boiling point show an upward trend from fluorine to iodine. In contrast, periodic properties like electronegativity, reactivity, and electron affinity decrease down the group.        

Electron configurations of halogens indicate that they have seven valence electrons and are one electron short of attaining their nearest noble gas configuration. Therefore, halogens exhibit high electronegativities with a strong tendency to gain one additional electron to complete their octet, making them highly reactive and powerful oxidizing agents compared to other groups.

Fluorine is the most potent oxidizing agent amongst halogens and iodine the lea