Why does liquid bromine change to gas at room temperature?

Answer 1

Actually, Bromine is a Liquid at room temperature it never changes to a gas at room temperature when it is heated up to 300 or so...Kelvin.

Answer 2

Liquid bromine has weak intermolecular forces, which allow individual molecules to easily overcome these forces and escape into the gas phase at room temperature. This is why liquid bromine evaporates and changes into a gas.