Here's why:

* Valence Electrons: Fluorine has 7 valence electrons (electrons in its outermost shell).

* Octet Rule: Atoms tend to gain, lose, or share electrons to achieve a stable configuration of 8 valence electrons (the octet rule).

* Bond Formation: Fluorine needs one more electron to complete its octet. It achieves this by sharing one electron with another atom, forming a single covalent bond.