Here's why:
* Bonding: HBr forms a single covalent bond between the hydrogen atom and the bromine atom.
* Electronegativity: Bromine is more electronegative than hydrogen, meaning it attracts the shared electrons in the bond more strongly.
* Lone pairs: Bromine has three lone pairs of electrons.
Because of the single bond and the lone pairs on bromine, there are no forces pushing or pulling the atoms out of a straight line. This results in a linear geometry.
