Chemical activity of fullerene molecules is associated with a partially radical character of these molecules caused by the presence of effectively unpaired electrons (EUE). Values of the total number of N D and partial distribution N DA of EUE over the atoms in a singlet state of molecules C60 and C70 have been calculated. "Chemical portraits" of molecules are presented, and N DA values are proposed to be used as indicators for chemical activity of atoms and to predict thereby the position of favorable atom-atom contacts in addition reactions with participation of these molecules. Bases of "computational synthesis" procedures for fullerene C60 derivatives are exemplified by initial phases of its fluorination. © 2006 Springer Science+Business Media, Inc.