Ukuqonda Ukuvumelana Nezibonelo
I-Pendahuluan
Kumakhemikhali, indlela ama-athomu ahlangana ngayo ukuze akhe into ethile inquma kakhulu izakhiwo zaleyo nto. Umqondo owodwa obalulekile ochaza ukuthi isibopho sama-athomu yi-covalence. Izibopho ze-covalent (covalence) zivame ukutholakala kuma-compound akhiwe yizinto ezingezona ezensimbi, isibonelo emanzini (H₂O), i-carbon dioxide (CO₂), i-methane (CH₄), kanye nama-organic compounds ahlukahlukene ayisisekelo sokuphila. Ukuqonda incazelo ye-covalence kanye nezibonelo kuzosisiza siqonde ukuthi izakhiwo zama-molecule zakhiwa kanjani, ukuthi kungani izinto ezithile zinamaphuzu athile okubila, ukuthi kungani amanye ama-compounds encibilika kalula emanzini, nokuthi kwenzeka kanjani ukusabela kwamakhemikhali.
Ukuqonda i-Covalence
I-Covalence ingumqondo ohlobene nokwakheka kwezibopho ze-covalent, okuyizibopho zamakhemikhali ezenzeka lapho ama-athomu amabili abelana ngama-electron amabili ukuze kufezwe ukuzinza. Ngokuvamile, ama-athomu afuna ukufeza ukucushwa kwe-electron okuzinzile njengegesi ezihloniphekile (umthetho we-octet), okuwukuthi kunama-electron ayi-8 egobolondweni lawo langaphandle (yize kukhona okunye okuhlukile). Ngenxa yokuthi ama-athomu angewona awensimbi avame ukuba ne-electronegativities ephezulu futhi "awalahlekelwa kalula" ama-electron, indlela engenzeka kakhulu yokufeza ukuzinza ukwabelana ngama-electron, kunokuba uwanike noma uwamukele ngokuphelele njengasezibophweni ze-ionic.
Ngamanye amazwi, ngenkathi kuma-ionic bonds ama-electron edluliselwa esuka kwi-athomu eyodwa aye kwenye, kuma-covalent bonds ama-electron ayabiwa. Ama-electron abiwe akha i-bonding electron pair, "ehlanganisa" ama-nuclei amabili e-athomu ndawonye ukuze akhe i-molecule eyodwa noma i-covalent bond.
Kungani Kuvela Izibopho Ze-Covalent?
Izibopho ze-covalent zenzeka ngenxa yomfutho wokufinyelela esimweni samandla esiphansi nesizinzile. Lapho ama-athomu amabili esondelana, ama-electron awo e-valence angabiwa, okwenza kubonakale sengathi i-athomu ngayinye "ine" inani elanele lama-electron egobolondweni layo langaphandle. Lokhu kwenza uhlelo luzinze kakhulu kunalapho ama-athomu emi wodwa.
Isibonelo, i-athomu ye-hydrogen (H) ine-electron eyodwa futhi ifuna ukufeza ukuzinza njenge-helium (He) nama-electron amabili. Ama-athomu amabili e-hydrogen angabelana ngama-electron amabili, akhe i-molecule ye-H₂. I-athomu ngayinye ye-H₂ manje "izizwa" sengathi inama-electron amabili egobolondweni layo lokuqala, ngaleyo ndlela ifinyelele ukuzinza.
Izinhlobo zezibopho ze-Covalent
Ama-covalent bonds angahlukaniswa ngokusekelwe enanini lama-electron pair abiwe futhi ngokusekelwe nasemehluko ku-electronegativity phakathi kwama-athomu.
1. Ngokusekelwe enanini lama-electron pair abiwe
1. Isibopho se-covalent esisodwa: ukwabelana ngepheya elilodwa lama-electron.
Isibonelo: H—H ku-H₂, noma C—H ku-CH₄.
2. Isibopho se-covalent esiphindwe kabili: ukwabelana ngamabili ama-electron.
Isibonelo: O=O ku-O₂, noma C=O ku-CO₂.
3. Isibopho se-covalent esiphindwe kathathu: ukwabelana ngamabili ama-electron amathathu.
Isibonelo: N≡N ku-N₂.
Uma ama-electron pair amaningi abelana, isibopho siqina futhi ibanga eliphakathi kwama-athomu lifushane.
2. Kususelwa ku-polarity
1. Izibopho ze-covalent ezingezona ezomhlaba
Kwenzeka lapho ama-athomu womabili ene-electronegativities efanayo noma efana kakhulu, ukuze umbhangqwana wama-electron wabelane ngokulinganayo.
Isibonelo: H₂, O₂, N₂, Cl₂.
2. Izibopho ze-covalent ezimaphakathi
Lokhu kwenzeka lapho umehluko ku-electronegativity ubalulekile ngokwanele ukuthi umbhangqwana wama-electron ukhangwa kakhulu yi-athomu eyodwa. Lokhu kuphumela ekushajweni okungaphelele (δ⁺ kanye ne-δ⁻).
Izibonelo: H—Cl ku-HCl, O—H ku-H₂O.
Kubalulekile ukuhlukanisa ukuthi isibopho se-polar asisho njalo ukuthi i-molecule iyi-polar; i-polarity ye-molecule nayo ithonywa ukuma kwe-molecule (i-geometry).
Izibonelo Zokubambisana Ezingxenyeni Zansuku Zonke
Nazi ezinye izibonelo ezilula ukuzithola empilweni yansuku zonke:
1. Amanzi (H₂O)
Amanzi ayisibonelo esibalulekile senhlanganisela enezibopho ze-polar covalent. I-athomu ye-oxygen ine-electronegative kakhulu kune-hydrogen, ngakho-ke umbhangqwana owodwa okhangwa kakhulu yi-oxygen. Lokhu kunikeza amanzi izakhiwo eziyingqayizivele njengekhono lawo lokuncibilikisa izinto eziningi, ukucindezeleka okuphezulu kobuso, kanye nephuzu lokubila eliphakeme uma kuqhathaniswa namanye ama-molecule amancane.
Ku-H₂O, kunezibopho ezimbili ze-polar O—H. Ngaphezu kwalokho, ukuma "okugobile" (hhayi okuqondile) kwama-molecule amanzi kusho ukuthi izikhathi zawo ze-dipole azikhanseli omunye komunye, ukuze ama-molecule amanzi ewonke abe yi-polar.
2. I-carbon dioxide (CO₂)
I-CO₂ inezibopho ezimbili ze-covalent ezimbili phakathi kuka-C no-O (O=C=O). Isibopho se-C=O si-polar, kodwa i-CO₂ siqondile, ngakho-ke izikhathi zayo ezimbili ze-dipole ziyahlukana. Ngenxa yalokho, i-molecule ye-CO₂ ayi-polar ngokuphelele. Lesi esinye sezizathu ezenza i-CO₂ ingancibiliki emanzini kunezinto ezihlanzekile ze-polar, yize isengasabela ekwakheni i-carbonic acid ngaphansi kwezimo ezithile.
3. I-Methane (CH₄)
I-Methane iyinhlanganisela elula yezinto eziphilayo eyakhiwe yizibopho ezihlanganisiwe phakathi kuka-C no-H. Ngokuvamile, i-CH₄ ayiyona i-polar ngoba ukuma kwayo kuyi-tetrahedral symmetrical kanti umehluko we-electronegativity phakathi kuka-C no-H awumkhulu kakhulu. I-Methane iyisakhi esiyinhloko segesi yemvelo futhi isetshenziswa kabanzi njengophethiloli.
4. I-oksijini (O₂) kanye ne-nitrogen (N₂)
I-O₂ inesibopho esiphindwe kabili se-covalent (O=O), kanti i-N₂ inesibopho esiphindwe kathathu se-covalent (N≡N). Isibopho esiphindwe kathathu ku-N₂ sinamandla kakhulu, okwenza i-nitrogen ingasabeli kahle (ingasabeli kalula) ngaphansi kwezimo ezijwayelekile. Yingakho i-nitrogen ibusa umkhathi woMhlaba kodwa ingasabeli kalula ngaphandle kwezimo ezikhethekile noma usizo lwe-catalyst.
5. I-hydrogen chloride (HCl)
I-HCl iyisibonelo sesibopho se-polar covalent. I-Chlorine (Cl) ine-electronegative kakhulu kune-hydrogen, ngakho-ke ama-electron ayo akhangwa kakhulu yi-Cl, okuholela ekushajweni okungaphelele. Uma incibilikiswa emanzini, i-HCl iyayi-ionizes ukuze yakhe i-H⁺ kanye ne-Cl⁻, okwenza yaziwe njenge-asidi enamandla. Lokhu kubonisa ukuthi i-compound ingaba nesibopho se-covalent kodwa ikhiqize ama-ion esixazululweni.
6. I-Amoniya (NH₃)
I-Ammonia inesibopho esihambisanayo phakathi kwe-N ne-H. I-molecule ye-NH₃ inesimo se-trigonal pyramidal futhi iyi-polar. I-Ammonia isetshenziswa kabanzi embonini yomanyolo, ekuhlanzeni, nasezinqubweni ezahlukahlukene zamakhemikhali. I-polarity ye-Ammonia iyivumela ukuthi isebenzisane kakhulu namanzi.
Izici Ezijwayelekile Zama-Covalent Compounds
Ngokuvamile, ama-compounds e-covalent anezici ezilandelayo (nakuba kukhona okuhlukile):
1. Eziningi zakhiwe ngezinto ezingezona ezensimbi.
2. Ngokuvamile zinamaphuzu okuncibilika nokubila aphansi kunamakhemikhali e-ionic, ikakhulukazi kuma-molecule amancane.
3. Ama-compound angenayo i-polar covalent avame ukungancibiliki emanzini, kodwa ancibilike ezincibilikisini ezingeyona i-polar.
4. Ungaqhubeki nogesi usesimweni esiqinile; eminye ingaqhubeki nogesi uma ixutshwe ne-ionized kusisombululo (isb. i-HCl emanzini).
5. Kutholakala kumakhemikhali amaningi e-organic afana nama-hydrocarbon, ama-alcohol, ama-organic acid, kanye namaprotheni.
I-Penutup
I-Covalence ingumqondo oyisisekelo ochaza ukuthi ama-athomu, ikakhulukazi ama-nonmetal, akha kanjani izibopho ngokwabelana ngama-electron pairs. Izibopho ze-Covalent zingaba zodwa, ziphindwe kabili, noma zibe kathathu, futhi zingaba polar noma zingabi polar. Izibonelo zijwayeleke kakhulu empilweni yansuku zonke, njengamanzi (H₂O), i-carbon dioxide (CO₂), i-methane (CH₄), i-oxygen (O₂), i-nitrogen (N₂), kanye ne-hydrogen chloride (HCl). Ngokuqonda incazelo ye-covalence nezibonelo, singaxhumanisa kalula isakhiwo sama-molecule nezakhiwo zomzimba nezamakhemikhali zento ethile.
Uma ungathanda, ngingangeza inguqulo yesayensi kakhulu yalesi sihloko (ngengxoxo ngezakhiwo zikaLewis, umthetho we-octet, kanye ne-molecular geometry) noma inguqulo elula yabafundi besikole samabanga aphezulu.
