Icansi lezinhlwa

Icansi lezinhlwa liwumbukiswano oyicansi wezinhlwa zevanga, ezihlelwe ngenani lobuchwe, ukumiswa kwenzuba, kanye nezakhi zevanga eziphindaphindayo. Liyisicabayo esidwetshiwe somthetho wezinkathi, othi izakhi zezinhlwa zevanga ziveza icishelo lobunkathi oluncike enanini lazo lobuchwe. Icansi lihlukaniswe laba izinxande ezine ezibizwa izingquklu (blocks). Izinhlu noma imigqa eyisikhombisa yecansi, ibizwa ngokuthi izinkathi. Imigqobe (columns) ibizwa ngamaqembu, aqukethe izinhlwa ezinezici ezifanayo ngokwevanga. Amaqembu ayisithupha amukele amagama kanye namanani abazinikiwe: isibonelo, izinhlwa zeqembu lesi-17 ziyizakhatshiwo (halogen); kanti iqembu le-18 lingamahowo ekhethelo (noble gases). Imithambeko kuyinto egcwele kulo lonke ucansi, njengoba isici esingenkimbi (nonmetallic) sikhula kusuka kwesobunxele kuya kwesokudla, futhi kusuka phansi kuya phezulu eqenjini, futhi isici sobunkimbi (metallic) sikhula ekuqombotheni okumalungana. Isizathu esiyisisekelo salemithambeko ukuhleleka kwezinzuba emachweni. Icansi ngokukhethekile lifaka amachwe angenamlelesa nanenani elilinganayo lezinelesi ezinomlelesa ovumayo kanye nezinzuba ezinomlelesa ophikayo ohlwini lwendawo eyodwa.