How do halogens form diatomic molecules?

Halogens form diatomic molecules by sharing a pair of electrons between two atoms of the same element.

Halogens are elements found in Group 7 of the Periodic Table. They include fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At). These elements are known for their high reactivity, which is due to their electron configuration. Each halogen atom has seven electrons in its outermost shell and needs one more to achieve a stable, full outer shell of eight electrons, which is the most stable configuration according to the Octet Rule.

To achieve this stable configuration, halogens can either gain an electron from another atom or share an electron with another atom. In the case of diatomic molecules, two atoms of the same halogen element share a pair of electrons, forming a covalent bond. This shared pair of electrons counts as one electron for each atom, thus filling their outer shells and making them stable. This type of bond is known as a single covalent bond.

For example, two chlorine atoms can share a pair of electrons to form a chlorine molecule (Cl2). Each chlorine atom contributes one electron to the shared pair, and this shared pair of electrons is counted as one electron for each atom. This means that each chlorine atom now has a full outer shell of eight electrons, making the molecule stable.

This process of forming diatomic molecules is common to all halogens. It is this ability to easily form covalent bonds with themselves and with other elements that makes halogens so reactive and versatile in chemical reactions.