* Electronegativity: Bromine (Br) is significantly more electronegative than carbon (C) and hydrogen (H). This means bromine attracts electrons more strongly in the C-Br bond.

* Polar Covalent Bonds: The C-Br bond is a polar covalent bond, with a partial negative charge (δ-) on the bromine atom and a partial positive charge (δ+) on the carbon atom.

* Molecular Geometry: The molecule has a tetrahedral shape. The polar C-Br bond creates a dipole moment, which is a measure of the separation of charge within the molecule. The other C-H bonds also have dipole moments, but they are much smaller and cancel each other out.

* Overall Dipole Moment: The overall dipole moment of the molecule points towards the bromine atom.

In summary, the polar C-Br bond and the molecular geometry result in a net dipole moment, making CH3Br a polar molecule.