The quantum-mechanochemical-reaction-coordinate approach has disclosed atomically matched peculiarities that accompany the deformation-failure-rupture process occurring in nanographenes. The high stiffness of the graphene body is provided by the benzenoid unit. The anisotropy of the unit mechanical behavior in combination with different configurations of the unit packing with respect to the body C-C bond chains forms the ground for the structure-sensitive mechanism of the mechanical behavior that is drastically different for two different deformation modes. The zig-zag deformation mode is particularly manifested with the formation of one-atom chains. The approach allows tracing a deformation-stimulated change in the chemical reactivity of both the nanographene body and its individual atoms. © 2011 Pleiades Publishing, Inc.