Dimiti Mandeevu

Dimiti Mandeevu (Dmitri Mendeleev) yafulumya omweso gw'endagakintu ogwasooka mu 1869. Yalaga nti singa endagakintu zisengekebwa okusinziira ku buzito bw'obuziba / atomu (atomic weight), kivaamu omusengeko (pattern) nga ebinnyonnyozo by'endagakintu (erementi) bidding’ana mu bugalamivu (periodically).

Kyokka okusinziira ku kunoonyereza kwa munnassomabutonde oba munnassomabuzimbe Henry Moseley, kyakakasibwa nti Omweso gw'Endagakintu (Table of Elements)gwesigamye ku "namba y'atomu edda waggulu" (increasing atomic number) so si ku buzito bwa atomu. Omweso guno ogwalimu  ennongoosereza gwali gusobola okukozesebwa okulagula ebinnyonnyozo by'endagakintu  ezitannaba kuvumbulwa.

Endagakintu  mu Mweso ogw’Emigaramiro zisengekeddwa mu migaramiro (rows) n’ebibinja (groups. Buli gumu ku migaramiro omusanvu ejjuzidwamu mu nzering’ana ne namba y'atomu (oba namba y'akaziba atomic number).

Ebibinja birimu endagakintu  ezirina "obusengeke bw’obusannyalazo" bwe bumu (same electron configuration) mu kire oba ekisosonkole ekyo kungulu, ekiviirako erementi eziri mu kibinja okuba nga birina ebinnyonnyozo by'enkyusabuziba(chemical properties) ebigwa mu kiti ekimu.

Obusannyalazo mu kisosonkole eky’o ku ngulu buyitibwa "busanyalazo bwa kiyayaano" (valence electrons). Obusannyalazo obw'ekiyayaano bwe busalawo ku binnyonnyozo n’ekikyusabuziba eky'endagakintu era bwenyigira mu nkwaso ez'enkyusabuziba (chemical bonding). 

Nambiso z’ekirooma ezisangibwa waggulu wa buli kibinja ziraga omuwendo gw’obusannyalazo obwa ekiyayaano ekya bulijjo.