  The radii of nucleon distribution and neutron skin in nuclei beyond the
\beta-stability line are studied within the extended Thomas-Fermi
approximation. We show that the growth of neutron skin in unstable nuclei does
not obey the saturation condition because of the neutron coat. The neutron coat
indicates the possibility of giant neutron halo which is growing with moving
away from the beta stability line. We demonstrate the presence of strong shell
oscillations in the charge radius R_C and the relation of R_C to the isospin
shift of neutron-proton chemical potentials \Delta\lambda =\lambda_n-\lambda_p
for nuclei beyond the beta-stability line at fixed value of mass number A.
