Indlela ukucacisa Valence

Igama elithi "Valence ka" ulimi Latin ( «Valens») ngokuvamile lihunyushwa ngokuthi 'ezinethemba amandla. " Ngokokuqala ngqá ke ohlala kuso kuyakhulunywa ngaso ekuqaleni kwekhulu le-15, kodwa inani layo ( "isidakamizwa" noma "akhiphe") zazingenzelwanga nge incazelo yesimanje. Umsunguli lo mqondo ka Valence kuyinto wemithi odumile IsiZulu E. Frankland. Kanti yena 1852 eshicilelwe iphepha lapho abangu uchazwe kabusha zonke lezi zinkolelo-mbono kanye ezizathwini ezazikhona ngaleso sikhathi. Kwaba Eduardom Franklendom wethula umqondo wegama elithi "amandla zezinzwa", elaba isisekelo isifundiso Valence, kodwa impendulo yombuzo othi "kanjani ukuthola Valence?" Ngaleso sikhathi sasingakafiki washayelwa.

indima enabileko ukuthuthukiswa kwemfundiso yokuziphendukela kukhala yi uFriedrich August Kekule (1857), u-Archibald Scott Cooper (1858), A. M. Butlerova (1861), A. von Hoffmann (1865). Ngo-1866, uF A. Kekule e ebhukwinitifundvo yakhe ekhonjiwe stereochemical imodeli chemical molecule ne-carbon-athomu ukucushwa tetrahedral ngesimo imidwebo, okuyinto kwaba sobala kanjani ukucacisa valency, isib, i-carbon.

Kubaluleka theory zanamuhla zokukhulekela kunenze nisondelane chemical kukhona ukusebenza quantum-mechanical, okubonisa ukuthi laba Imininingwane electron pair ezakhiwe ukuxhumana ngama-athomu amabili. Atoms electrons ayibhangqiwe nge osebenzisa okufanayo, dudula futhi antiparallel uyakwazi ukwakha ezivamile electron pair. Isibopho chemical obakhiwa athomu amabili njengoba zisondela, kancane embozwe amafu electron. Ngenxa yalokho, phakathi cores ezimbili Kumiswa kwabantu kagesi, okuyinto bakhangwa nucleus kahle icala futhi i-molecule akheka kanjani. ukumelwa okunjalo mshini nokuxhumana ngama-athomu ezahlukene esitholakala chemical isibopho theory indlela noma isibopho Valence. Ngakho ngemva sonke, kungaba kanjani ukuba sithole Valence ka? Kuyadingeka ukucacisa inombolo izibopho ukuthi i-athomu ungakheka. Kungenjalo, ungakwazi ukuthi udinga ukuthola inombolo ye Valence electron.

Uma sisebenzisa ishadi lesikhathi, kulula ukuba baqonde indlela ukucacisa Valence timphawu ngokuvumelana nenani electron udonga lwangaphandle athomu. Zibizwa ngokuthi ama-Valence. Zonke izici eqenjini ngalinye (tihlelwe ngemakholamu) e amagobolondo yangaphandle kufanele inani elifanayo electron. Eqenjini lokuqala izakhi (H, Li, Na, K nabanye) has eyodwa Valence electron. Eyesibili (Be, MG, Ca, Sr, nokunye) - amabili. Okwesithathu (B, Al, Ga, njll) - I-ezintathu. Ekhulwini lesine (C, Si, Gen, njll) - Valence electron ezine. Ekhulwini lesihlanu iqembu isici (N, P, Njengoba, njll) by Valence electron ezinhlanu. Ungaqhubeka, ngoba kusobala ukuthi isibalo electron udonga lwangaphandle efwini electron kuyoba kulingana nesibalo etafuleni iqembu gqwa. Nokho, lokhu libaphatheleni amaqembu amathathu okuqala lezinkathi eziyisikhombisa futhi imigqa yabo okungekuhle ngisho (nezikhathi ahlelwe imigqa kanye imigqa etafuleni). Kusukela ngenkathi yesine futhi iqembu lesine (isib Ti, Zr, hf, Ku) ohlangothini tincenye subgroups ezisesandleni ngisho amareyi akhona e udonga lwangaphandle inani electron, ngaphandle inombolo iqembu.

Umqondo "Valence" ngakho konke lokho isikhathi uye washintsha abalulekile. Okwamanje akukho okwakha noma nencazelo yalo ngokwesayensi. Ngakho-ke, ikhono ukuphendula umbuzo "Indlela ukucacisa Valence?" Ingabe ngokuvamile isetshenziselwe izinjongo methodological. Valence Kusolwa ama-athomu ikhono angene ukuphendula engqamuzaneni ukuze izibopho zamakhemikhali ezibizwa ngokuthi covalent. Ngakho-ke kungase Valence uzwakalise kuphela yinombolo.

Ngokwesibonelo, indlela ukucacisa Valence kuyi-athomu ye-sulphur e yingxube njenge-hydrogen sulfide, noma sulfuric acid. Ukuze uthole i-molecule lapho athomu sulphur is banamathele athomu amabili e-hydrogen, i-Valence we-sulphur ukuba hydrogen ulingana ezimbili. Ngo-molecule ye-sulfuric acid Valence yayo i-oksijini singamakhulu ayisithupha. Futhi eqinisweni, kuzo zombili izindawo la Valence anda kuvumelana inani eliphelele degree of namachibi kuyi-athomu ye-sulphur kulezi ama-molecule. Njengoba H2S-molecule ayo degree of namachibi ngeke -2 (kusukela ukuminyana electron we kumiswa kugudlukela ngenxa athomu nesibabule, okungukufa electronegative ngaphezulu). Esikhathini molecule H2SO4 inombolo namachibi zama-athomu sulphur ilingana eziyisithupha (kusukela ukuminyana electron kugudlukela ku electronegative-mpilo athomu).