* Electronegativity Difference: Sodium (Na) is a metal with a low electronegativity, while bromine (Br) is a nonmetal with a high electronegativity. This significant difference in electronegativity leads to the transfer of electrons from sodium to bromine.

* Formation of Ions: Sodium loses an electron to become a positively charged sodium ion (Na+). Bromine gains an electron to become a negatively charged bromide ion (Br-).

* Electrostatic Attraction: The oppositely charged ions attract each other electrostatically, forming the ionic bond.

Therefore, the strong electrostatic attraction between the sodium and bromide ions results in the formation of an ionic compound, sodium bromide.