  New formulas to calculate the nuclear charge radii and the nuclear binding
energies have been derived in the framework of an alpha-cluster model. The
particular features of the model are two assumptions that the proton-neutron
pair interactions are responsible for adherence between alpha-clusters and that
the proton and the neutron from a proton-neutron pair have equal nuclear
potentials. These assumptions allow one to determine the charge and Coulomb
radii in dependence on the amount of proton-neutron pairs in the nucleus.
Unlike the Weizsacker's formula to calculate nuclear binding energies, in the
model the binding energies of alpha-clusters and excess neutrons are estimated
separately. The calculated values are in a good agreement with the experimental
data.
