  We predict general trends for surface segregation in a binary metal cluster
based on the difference between the atomic properties of the constituent
elements. Considering the attractive and repulsive contributions of the
cohesive energy of an atom in a cluster, energetically most favorable sites for
a guest atom on a pure metal cluster is determined. It is predicted that for
adjacent elements in a row of the periodic table, the bimetallic system would
be more stable if the component with smallest valence electron density is
placed on the surface. On the contrary, for well separated components in the
periodic table, the bimetallic cluster would be more stable if the component
with the smallest core electron density is placed inside. Such chemical {\bf
ordering trends} in the lowest energy configurations of Pt-Au, Pt-Pd and Pt-Ni
binary alloy clusters are verified for their 561 atom systems through simulated
annealing process. It is predicted that the Ir, Rh, Ni, Pd atoms would tend to
be located inside the Ir-Pt, Rh-Pd, Ni-Cu and Pd-Ag bimetallic nanoclusters,
respectively.
