Obusannyalaza mu kisosonkole eky’o kungulu buyitibwa busanyalaza bwa valansi (valence electrons). Obusannyalaza obwa valansi bwe busalawo ku binnyonnyozo n’entomaggana eya kemiko eya erementi era bwenyigira mu nkwaso ez'enkyusabuziba (chemical bonding).