Here's why:

* Electronegativity: Bromine is much more electronegative than hydrogen, meaning it has a stronger pull on shared electrons. However, the difference in electronegativity isn't large enough to create an ionic bond.

* Sharing Electrons: Instead of one atom completely transferring an electron to the other, they share a pair of electrons to achieve a stable electron configuration.

This shared electron pair forms the covalent bond between the hydrogen and bromine atoms, resulting in the formation of hydrogen bromide (HBr).