The atomic and group compressibility

Using classical definition of compressibility and the electrostatic attractive force in an atom, a new atomic property, which is called Atomic Compressibility (β) is introduced for atoms. This parameter is calculated for 45 atoms and it is shown that in those cases for which the effective atomic polarizabilities are available (H, C, N, O, F, S, Cl, Br, I), the obtained atomic compressibilities have a linear relation with polarizabilities. Then for a molecule, Group Compressibility (Gβ) is defined as the summation of atomic compressibilities of constituted atoms in the molecule. For a wide range of molecules with different functional groups, which their experimental polarizabilities are given in literature, group compressibilities are calculated. A plot of group compressibility vs. polarizability shows considerable linearity (the correlation coefficient is 0.996648).