The physical properties of alkyl halides are influenced by the polarity of `C- X` bond.

The bond length of `C - X` bond in alkyl hal ides follow the order `MeI > MeBr >MeCl > MeF.` Vapour phase dipole moments in Me - `X` varies as `MeCl > MeF > MeBr > MeI` .This is because dipole moment depends on electronegativity of halogen as well as on the bond length.

The order of boiling points of alkyl halides is `Mel > MeBr > MeCI > MeF,` which is influenced by the decreasing van der Waal forces of attraction between them. Among polyhalogen compounds, boil ing point decreases as `C Cl_4 > CHCl_3 > CH_2Cl_2 > CH_3Cl`. This is due to accumulation of `C's` on `CH_4`, increases the molecular mass and size, thus van der Waals forces increases and boil ing point also increases.

The densities of alkyl iodides and bromides is more than that of `H_2O` that the densities of alkyl chlorides and fluorides in less than that of `H_2O`. The order of densities of alkyl halides and `H_2O` is `R I > RBr > H_2O > RCl > RF` and the densities of polychloro methane varies as `C Cl_4 > CHCl_3 > CH_2Cl_2 > H_2O > CH_3Cl`. The alkyl halides are in general insoluble in water.