Chemical bonding between two atoms is necessarily with an electrical moment arising out of the difference in electronegativity of two atoms. This means that every bond carries with it an electrical moment called the bond moment.The dipole moment of a molecule is really the vectorial sum of the individual bond moment present in it. To compute the dipole moment it is necessary to find out the values of various bond moment in the moment of different bonds are as given. {:("Bond",oversetto(H-C), " ",oversetto(C-Cl)," ",oversetto(C=O)),("Bond moments",0.4 D ," ", 1.5 D, " ", 2.5D):} The group moments of few groups as given {:("Group",NO_2,OH,CN,CH_3),("direction of dipole","toward N","towards O","towards N","away from" CH_2),("Dipole moment",4D,1.6D,3.8 D,0.4D):} In the acetone molecule considering the normal planar structure, the observed dipole moment of acetone molecule is -