Sidee si loo ogaado valence ah

Erayga "valence ah" af Laatiin ( «valēns») loo tarjumay sida "isagoo ciidanka." Markii ugu horeysay waxaa ku xusan in qarnigii hore 15-kii, laakiin miraheeda ( "daroogada" ama "laga soosaaray") waxba u qaban la fasiraadda casriga ahi lahaa. Aasaasihii of fikradda ah ee valence waa farmashiyaha Ingiriisi caanka E. Frankland. Waxa uu in 1852 la daabacay warqad ah in, kuwaasi oo ay reinterpreted oo dhan aragtiyaha iyo fikradaha in jirey waagaas. Waxay ahayd Eduardom Franklendom soo bandhigay fikradda ah "xoog connective", kaas oo noqday saleysan cilmiga valence, laakiin jawaabta su'aasha ah "Sidee si aad u ogaato valence ah?" Waqtigaas aan weli la diyaariyey.

kaalin dheeraad ah ee horumarinta aragtida ah lagu ciyaaray by August Friedrich ku Kekule (1857), Archibald Scott Cooper (1858), A. M. Butlerova (1861), A. von Hoffmann (1865). In 1866, F. A. Kekule in uu buugga daliishaday taagoo model kiimikada stereochemical la eb carbon qaabeynta tetrahedral ee foomka of sawirada, kaas oo noqday cad sida si loo ogaado valency ah, tus, carbon.

Fundamentals of aragtida casriga ah ee lagala kulmo kiimikada yihiin waxqabadka galmada-farsamo ah, oo muujinaya in tirada guud ee labada ciyaaryahan electron sameeyay by dhexgalka laba atamka. Atamka la electrons unpaired la dhigeeysa isku midka ah, si kada ah iyo antiparallel awood u sameynta labo ka mid electron caadi ah. bond kiimikada sameeyay inta u dhexeysa laba atamka sida ay u dhowaan, waxaa qayb ahaan daboolay daruuro electron ah. Sidaas darteed, inta u dhaxaysa labada diirkja waxaa la aasaasay cufnaanta la'aan korontada, kaas oo soo jiitay in xuduntii wanaagsan eedeeyay iyo Britain ayaa la aasaasay. matalaad ah hab ay of dhexgalka ee atamka kala duwan sida caddeynayaa habka aragti bond kiimikada ama bond valence ah. Sidaas dib oo dhan, sida si loo ogaado valence ee? Waxaa lagama maarmaan ah si loo ogaado tirada bonds in la eb sameysmi karaa. Haddii kale, waxaad odhan kartaa in aad u baahan tahay si aad u hesho tirada of electrons valence.

Haddii aan u isticmaalno miiska wareegsan, waa ay fududahay in la fahmo sida si loo ogaado valence ee element sidii ay tirada electrons in qolof ah barxadda dibadda la eb. Waxaa loo yaqaan valence. Dhamaan xubno ka ah ee koox kasta (qabanqaabiyaa columns) ee qolofka dibadda leeyihiin tiro la mid ah electrons. In kooxda koowaad ee canaasiirta (H, Li, Na, K iyo kuwa kale) uu leeyahay mid ka mid electron valence. Shirka labaad ee (Noqo, mg, Ca, Sr, iyo wixii la mid ah) - laba. A saddexaad (B, Al, Ga, iwm) - saddex. In afraad (C, Si, GE, iwm) - afar electrons valence. In element shanaad group (N, P, Sida, iwm) by shan electrons valence. Waxaad sii wadi kartaa on, sababtoo ah waa wax iska cad in tirada electrons in qolof ah barxadda dibadda ee daruur electron uu noqon doono si siman u tiro group miiska wareegsan. Si kastaba ha ahaatee, waxan haystaa, waayo, saddex kooxood ugu horeysay ee lix iyo saf kisi iyo dhaban ay (muddooyinka qabanqaabiyaa saf iyo saf oo miiska). Tan iyo muddadaas afaraad oo kooxda afaraad (tus, Ti, Zr, HF, Ku) xubno ka dhanka ah kooxaha ku jira xitaa saf ku jira qolof ah barxadda dibadda ee tirada electrons, aan ka ahayn tirada kooxda.

Fikradda ah "valence ah" waagaas oo dhan ayaa isbedelo la taaban karo. hadda ma jirto heerarka ama fasirkiisa ee sayniska. Sidaa darteed, awood u leh inay ka jawaabaan su'aasha ah "Sidee si loo ogaado valence ah?" Waxaa sida caadiga ah loo isticmaalo ujeeddooyin nidaamsan. Valence wareegay atamka awoodda galo dareen-celin la Britain si ay u sameeyaan bonds kiimikada yeedhay covalent. Sidaa darteed valence lagu sheegi kara oo kaliya abyoonaha ah.

Tusaale ahaan, sida si loo ogaado valence ee la eb baaruud in xeryahooda sida tayadda hydrogen, ama sulfuric acid. Waayo, Britain, halkaas oo la eb baaruud la addoonsi laba atamka hydrogen, valence ee baaruudda in hydrogen noqon doonaa siman laba. In Britain a of sulfuric acid ay valence oksajiinta waa lix. Oo ahaantii, labada kiis ee valence ah tiro ku beegan tahay qiimaha waadaxa ah heerka uu qayilo eb baaruud in u taagoo, kuwaas oo ah. Sida H2S Britain ay degree of qayilo doono -2 (tan iyo cufnaanta electron ee dhismaha la wareejiyay sabab u eb baaruudda, taas oo ka badan electronegative). In Britain ee tirada qayilo H2SO4 of atamka baaruud waa loo siman yahay ilaa lix (tan iyo cufnaanta electron la wareejiyay in la eb a oxygen dheeraad ah electronegative).