Question

Why do two fluorine atoms bond together $?$

Answer 1

First we have to know that Fluorine is the lightest, extremely reactive halogen denoted with the symbol $F$ and its atomic number is $9$ . The number of electrons in the outermost shell of an atom determines its tendency to form chemical bonds with other atoms. This outermost shell is known as the valence shell, and the electrons found in it are called valence electrons.

Complete Step By Step Answer:
Since $F$ is in the group $17$ of the periodic table and its electronic configuration is $1{s^2}2{s^2}2{p^5}$ . Then the outermost shell has $7$ valence electrons. Hence, a fluorine atom is unstable with $7$ electrons in its valence shell, so we need one more electron to achieve stability. This is according to the octet rule which states that an atom will gain or lose electrons until there are $8$ electrons in its valence shell. So, when two fluorine atoms come together, they each share one of their $7$ valence electrons to form a nonpolar covalent bond. Hence fluorine atoms bond together to form the fluorine molecule because both those atoms can obtain a full octet by the sharing of two electrons.

Note:
Fluorine is the most electronegative element and exists at standard conditions as a highly toxic, pale yellow diatomic gas. All Noble gases are electronically very stable. Atoms form chemical bonds to make their outer shells more stable.