Indlela ukufumanisa Valence

Igama elithi "Valence of" ulwimi Latin ( «valēns») liguqulelwe ngokuthi "ukuba amandla." Kuba okokuqala kubhaliwe okhankanywe benkulungwane ye-15, kodwa ke ixabiso layo ( "iziyobisi" okanye "isicatshulwa") bengenanto yakwenza sithathwa mihla. Ngunozala le ngcamango yokuba Valence yi ekhemesti odumileyo IsiNgesi E. Frankland. Yena ngo 1852 wapapasha iphepha apho zaye mbalwa zonke iingcamango kunye nokucingela ezazikho ngelo xesha. Yaba Eduardom Franklendom laqalisa ingcamango "amandla nokuqina", ezaba sisiseko imfundiso Valence, kodwa impendulo yombuzo "Indlela ukufumana Valence?" Ngelo xesha ndingazimisanga okwangoku saqulunqwa.

indima ngakumbi kuphuhliso theory ebidlalwe yi-Friedrich Agasti Kekule (1857), Archibald Scott Cooper (1858), A. M. Butlerova (1861), A. von Hoffmann (1865). Ngowe-1866, F. A. Kekule kwi incwadi yakhe ezibonisiweyo stereochemical iimolekyuli imodeli kwemichiza kunye carbon atom uqwalaselo tetrahedral ngohlobo imizobo, leyo kwacaca ukuba ukujonga indlela valency, umz, carbon.

Imithetho theory mihla ubuhlobo yamachiza komsebenzi umyinge-mechanical, ebonisa ukuba isibini electron iyonke akhiwa intsebenziswano-athom ezimbini. Atom kunye elektroni unpaired kunye ijikelezisa parallel dudula kunye nabakwaziyo antiparallel wokusungula kwisibini electron eqhelekileyo. Yinto imichiza olwakheka phakathi athom ezimbini njengoko besondela, engagqibekanga yogqunywe ngamafu electron. Ngenxa yoko, phakathi umphakathi ezimbini ezikhandelwa lexinene ku kagesi, nto leyo ifuna ukuba isiqalo ngokuqinisekileyo ityala kunye molecule kwakhiwa. Loo imbonakaliso indlela yentsebenziswano-athom ezahlukeneyo oxhasa umchiza bond indlela lethiyori okanye iqhina Valence. Ke emva koko, indlela ukujonga Valence na? Kuyimfuneko ukuba ukujonga inani kungqina ukuba i-atom kungenzeka. Kungenjalo, wena uthi kufuneka ufumane inani le electron Valence.

Ukuba sisebenzisa lwezakhi, kulula ukuqonda ukujonga ukuba izixa-Valence le element ngokwenani lwe elektroni kwi lwangaphandle ye atom. Zibizwa ngokuba Valence. Zonke izinto kwiqela ngalinye (amalungiselelo kwimiqolo) kwi kweqokobhe zangaphandle inani elifanayo electron. Xa iqela lokuqala lweziqalelo (H, Li, Na, K kunye nabanye) enye Valence electron. Le yesibini (Be, MG, Ca, Sr, njalo njalo) - ezimbini. A lesithathu (B, Al, Ga, njl) - ezintathu. Yenyanga yesine (C, Si, uGenubhati, njl) - electron ezine Valence. Xa element yesihlanu iqela (N, P, As, njl) ngokuthi electron ezintlanu Valence. Uyakwazi ukuqhubeka phambili, kuba kucacile ukuba inani elektroni kwi iqokobhe zangaphandle ilifu electron iya kulingana nenani iqela lwezakhi. Nangona kunjalo, oku liba ukuba amaqela ezintathu zokuqala lamathuba asixhenxe kunye nezintlu zabo angumnqakathi (ngamathuba ezicwangciswe mhloli ze table). Ukususela kwixesha yesine iqela yesine (umz, Ti, Zr, HF, Ku) izinto ecaleni subgroups ukuba kwi imikrozo zibe iqokobhe olungaphandle inani elektroni, ngaphandle kwenani qela.

Le mbono "Valence of" lonke eli xesha unenzondelelo iinguqu ezibalulekileyo. Okwangoku akukho standardised okanye ukutyhilwa kwalo yenzululwazi. Ngoko ke, ukukwazi ukuphendula umbuzo othi "Indlela ukufumanisa Valence?" Ngaba ngokuqhelekileyo esetyenziselwa iinjongo methodological. Valence kuzakuthathwa atom ubuchule bengena awasabela kunye molecule ukwenza iibhondi imichiza ebizwa covalent. Ngoko ke Valence ungavezwa kuphela inani elipheleleyo.

Umzekelo, indlela ukujonga Valence ngayo sulphur atom xa iikhompawundi ezifana emanzini, okanye sulphuric acid. Kuba molecule apho atom sulphur into yesondo athom ezimbini hydrogen, lo Valence ngayo sulphur ukuya hydrogen iya kulingana ezimbini. Xa molecule kwe-sulphuric acid Valence yayo oxygen ezintandathu. Yaye eneneni, kuzo zombini iimeko Valence ngamanani ingqamana ixabiso elililo iqondo igcwala ngayo sulphur atom kwezi iimolekyuli. Njengoko H2S molecule layo iqondo igcwala uya -2 (ukusukela lexinene electron ye ukuyilwa ishenxiselwe ngenxa atom isalfure, leyo electronegative ngaphezulu). Xa molecule H2SO4 igcwala inani sulfur ilingana ezintandathu (ukusukela loxinano electron ishenxiselwe kukho ioksijini atom electronegative ngaphezulu).