Ithiyori kaLewis ye-Acid-Base: Ukuqonda Okubanzi Nokuvamile
I-Pendahuluan
U-Isaac Newton wake wathi wayengabona kabanzi ngokuma emahlombe eziqhwaga, futhi kumakhemikhali, izimiso eziningi eziyisisekelo esizamukelayo namuhla zisekelwe emsebenzini wososayensi bangaphambili. Enye yalezi zinguquko ezibalulekile kwakuyi-Lewis theory yama-acid nama-base, eyethulwa nguGilbert N. Lewis ngo-1923. Le theory yenza kwaba lula futhi yandisa imiqondo yama-acid nama-base, okwenza kube lula ukuyiqonda nokusebenzisa kumakhemikhali wanamuhla.
Njengesingeniso, ake sibheke imibono ye-asidi nesisekelo ephakanyiswe ngaphambi kukaLewis. Okokuqala, i-Arrhenius acid-base theory ithi i-asidi iyinhlanganisela engandisa ukuhlushwa kwama-ion e-hydrogen (H⁺) esixazululweni, kuyilapho isisekelo siyinhlanganisela engandisa ukuhlushwa kwama-ion e-hydroxide (OH⁻). Kamuva, umphakathi wesayensi wamukela i-Bronsted-Lowry acid-base theory, eyandisa le ncazelo ngokuthi i-asidi ingumhlinzeki we-proton (H⁺) kanti isisekelo singumamukeli we-proton. Kodwa-ke, izincazelo zazo zombili le mibono zinemikhawulo, ikakhulukazi uma sicabangela ukusabela kwamakhemikhali okungahileli ngokusobala ama-proton noma ama-ion e-hydroxide.
Incazelo kanye nezimiso zama-Acids kanye nezisekelo Ngokusho kukaLewis
UGilbert N. Lewis waqaphela lokhu kushiyeka futhi waphakamisa incazelo ejwayelekile yama-acid nama-base. Ku-Lewis's acid-base theory, i-acid ichazwa njengokwamukela ama-electron-pair, kanti i-base ingumhlinzeki wama-electron-pair. Le ncazelo idlulela ngale kwezixazululo zamanzi kanye nokusabela okubandakanya ama-proton, okuvumela ukuqonda okubanzi kwezinhlobo ezahlukene zokusabela kwamakhemikhali.
Isibonelo esivamile sale mbono ukusabela phakathi kwe-ammonia (NH3) ne-boric acid (BF3). Kulesi simo, i-NH3 isebenza njengesisekelo se-Lewis ngoba inikela ngepheya lama-electron ku-athomu yayo ye-nitrogen ku-athomu ye-boron engenawo ama-electron ku-BF3, esebenza njenge-Lewis acid. Ukubopha phakathi kwepheya lama-electron lesisekelo se-Lewis kanye ne-electron acceptor ye-Lewis acid kuphumela ekwakhekeni kwe-adduct complex ezinzile kakhudlwana.
Esinye Isici Esibalulekile Senkolelo-mbono KaLewis
Enye yezinzuzo zethiyori kaLewis yikhono layo lokuchaza ukusabela okungenakuchazwa yithiyori ka-Arrhenius noma kaBronsted-Lowry. Lokhu kufaka phakathi ukusabela okungabandakanyi ama-proton ngokusobala. Isibonelo, ekwelashweni okuhlukahlukene kwe-organometallic kanye ne-coordination chemistry, ukusebenzisana phakathi kwezinsimbi zokuguquguquka kanye nama-ligand kungachazwa kalula kusetshenziswa imiqondo yama-asidi nezisekelo zikaLewis.
1. Umqondo Wezingqimba Zokujikeleza Nezinhlobo Zokuxhumana
Isici esibalulekile ku-Lewis acid-base theory ukuqonda ama-orbital kanye nezinhlobo zokusebenzisana phakathi kwama-acid nama-base. Ama-d-orbitals ezinsimbi zokuguquguquka, isibonelo, avame ukudlala indima ekuhlanganiseni nama-ligand asebenza njengezisekelo ze-Lewis. Lokhu kusebenzisana kuyisisekelo sokwakheka kwama-complexes okuxhumana, abalulekile ekusetshenzisweni okuningi kwamakhemikhali njenge-homogeneous catalysis kanye ne-supramolecular chemistry.
2. Ukuzinza Kwemikhiqizo
Ukuqina kwama-adduct complexes akhiwe phakathi kwama-Lewis acids kanye nezisekelo kungahlaziywa ngamapharamitha ahlukahlukene njengokuhambisana kwe-geometric, amandla okuxhumana kwe-electrostatic, kanye ne-polarity. Isibonelo, izakhiwo ezifana ne-electron affinity kanye nesakhiwo esinezinhlangothi ezintathu se-molecule zingathonya ukuthi i-electron pair ingamukelwa noma inikelwe ngamandla kangakanani.
3. Izicelo ku-Catalysis
Ithiyori ye-Lewis acid-base nayo idlala indima ebalulekile ekuhlaziyweni kwe-asidi, ikakhulukazi ekuhlaziyweni kwe-asidi-base okungafaniyo nokulingana. Ama-Catalyst asheshisa ukusabela ngokunikeza izindlela ezihlukile ngamandla okusebenza aphansi. Ama-catalyst amaningi ensimbi yokuguquguquka angasebenza njenge-Lewis acids ukuze asebenze ama-substrates ngokwamukelwa kwe-electron pair. Isibonelo, ekuhlaziyweni kwe-hydrogenation, izinsimbi ezifana ne-platinum noma i-palladium zingasiza ukubopha nokusebenza kwama-molecule e-hydrogen.
Ukuqhathanisa kanye nokulinganiselwa kwe-Lewis Theory
Nakuba ithiyori ye-Lewis acid-base inikeza ukumbozwa okubanzi, ayithathi indawo ngokuphelele yethiyori ye-Arrhenius ne-Bronsted-Lowry. Ithiyori ngayinye inamandla ayo kanye nokusetshenziswa kwayo ekuchazeni izinhlobo ezithile zokusabela. Isibonelo, ithiyori ye-Arrhenius iwusizo kakhulu ekuqondeni izakhiwo zama-electrolyte ezixazululweni zamanzi, kuyilapho ithiyori ye-Bronsted-Lowry isebenza kakhulu ekuphenduleni kwe-acid-base ezixazululweni ezingezona ezamanzi noma esigabeni segesi.
Umkhawulo owodwa wenkolelo-mbono kaLewis ukuthi izincazelo zayo zama-asidi nezisekelo zivamile kangangokuthi ngezinye izikhathi kunzima ukuzichaza ngqo ezimweni ezithile ngaphandle kosizo lwemiqondo ejulile yamakhemikhali njenge-quantum chemistry noma ukuhlaziywa kwe-spectroscopic. Ukufundisa nokusebenzisa inkolelo-mbono kaLewis kuvame ukudinga izibonelo eziqondile kanye nokuhlaziywa okujulile ukuze kuphumelele ngempela.
Isiphetho kanye nomthelela
Ithiyori yesisekelo se-asidi sikaLewis yandisa ukuqonda kwethu ukusebenzisana kwamakhemikhali ngezincazelo eziguquguqukayo kanye nokusetshenziswa okubanzi. Ngokuchaza ama-acid njengabamukeli be-electron-pair kanye nezisekelo njengabanikeli be-electron-pair, le thiyori ivula izilinganiso ezintsha ekuqondeni izinhlobo ezahlukene zokusabela kwamakhemikhali. Lokhu kufaka phakathi ukusabela okungahileli ngokusobala ama-ion e-hydrogen noma ama-ion e-hydroxide, njenge-coordination complexes kanye nokusabela kwe-catalytic ku-organometallic chemistry.
Sekukonke, iminikelo kaGilbert N. Lewis kule mbono ayiqinisanga nje kuphela izisekelo zekhemistri kodwa futhi inikeze ithuluzi eliwusizo lokucwaninga okwengeziwe kwesayensi. Ukuqonda okujulile ngale mbono kusisiza siqonde izenzakalo zamakhemikhali eziyinkimbinkimbi futhi kusheshisa ukusungula izinto ezintsha emikhakheni efana nemithi, izinto zesayensi, kanye nobuchwepheshe bamandla. Ngakho-ke, ngokuqaphela ukubaluleka kwale mbono ye-acid-base, singayiqonda futhi siyisebenzise ezifundweni eziningi kanye nezicelo.
