The crystal structure of sodium chloride (naci) is a simple cubic with the na and ci atoms alternating positions. each na atom is then surrounded by \ix ci atoms and likewise each c1 atom is surrounded by six na atoms. (a) sketch the atoms in a (100) plane. (b) assume the atoms arc hard spheres with nearest neighbors touching. the effective radius of na is i .0 a and the effective radius of ci is 1.8 a. determine the lattice constant. (c) calculate the volume dencity of na and c1 atoms. (d) calculate the mass density of nacl.