A wide class of phenomena in transition metals of the iron group is examined in the framework of the periodic model of Anderson. A method is devised for calculating the mass operator of d-electrons which can be used to find the Green's function with allowance for d-d interaction inside any given number of coordination spheres. Experiments on hydrogen adsorption in transition metals and the dependence of surface magnetic properties on orientation of the surface relative to the crystallographic axes are explained. A mechanism for reconstruction of the surface of transition metals is suggested.