Fluorine will share one electron to complete its outermost energy level.

Here's why:

* Fluorine's Electron Configuration: Fluorine has 9 electrons, with the configuration 2, 7. This means it has 7 electrons in its outermost shell (valence shell).

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

* Sharing for Stability: Fluorine needs one more electron to reach a full octet. It achieves this by sharing one electron with another atom, forming a single covalent bond.

Let me know if you'd like to explore other examples of covalent bonding!