Question

Describe a halogen atom in detail.

Answer 1

Halogens are elements of group seventeen of the periodic table. These include fluorine, chlorine, bromine, iodine and astatine. Halogens are highly reactive nonmetals, due to their high electronegativity and greater effective nuclear charge. They usually exist in the form of diatomic molecules.

Complete answer:
A halogen atom, whether it be of fluorine or iodine, consists of seven valence electrons in its outermost shell. Halogens therefore, often exhibit the oxidation state of $- 1$ , as on gaining one electron, they shall attain the nearest noble gas configuration. This tendency to attract electrons leads to an increased electronegativity among halogens. In fact, Fluorine has the highest electronegativity among all elements.
A halogen atom is relatively smaller to other elements in its period, as the atomic size decreases across a period. Thus, they have the smallest atomic radii in their respective periods. This also leads to a higher effective nuclear charge in halogen atoms.
Halogens have the highest electron gain enthalpy (negative) in their corresponding periods, as they are just one electron away from achieving the stable noble gas configuration. Due to a very low tendency to lose an electron, they have high ionization enthalpies.
Halogens (except fluorine) exhibit different oxidation states ranging from $- 1$ , $+ 1$ , $+ 3$ , $+ 5$ and $+ 7$ . Being the most electronegative element, fluorine cannot exhibit a positive oxidation state. Halogens are strong oxidizing agents. They also form interhalogen compounds. Some examples include: $Br{F_3}$ , $I{F_7}$ , $IC{l_3}$ etc.

Note:
Halogens occur in coloured forms. This colouration is due to absorption of radiation in the visible region. Fluorine is the only halogen that does not contain d orbitals, and hence cannot expand its octet. Also, interhalogen compounds are more reactive than halogens, due to their comparatively low bond strength.