Imibuzo Yesibonelo Ekhuluma Ngezibopho Ze-Covalent
I-Pendahuluan
Isibopho se-covalent uhlobo lwesibopho samakhemikhali lapho ama-athomu amabili abelana khona ngama-electron amabili noma ngaphezulu ukuze kufezwe ukucushwa okuzinzile kwama-electron, njengakumagesi ahloniphekile. Lesi sibopho sivame ukwenzeka phakathi kwama-athomu angewona awensimbi ane-electronegativities ephezulu futhi angahlukile kakhulu. Ukwakheka kwesibopho se-covalent kudlala indima ebalulekile kokubili kumakhemikhali e-organic kanye ne-inorganic futhi kuyisisekelo samakhemikhali amaningi esihlangana nawo nsuku zonke. Kulesi sihloko, sizoxoxa ngezibonelo eziningana ezihilela izibopho ze-covalent futhi sinikeze izixazululo zokusisiza siziqonde kangcono.
Imibuzo Eyisibonelo Nengxoxo
umbuzo 1
Nquma uhlobo kanye nenani lezibopho ze-covalent ezakhiwe ku-molecule ye-H2O (amanzi).
Ingxoxo:
I-molecule yamanzi iqukethe i-athomu eyodwa ye-oxygen (O) kanye nama-athomu amabili e-hydrogen (H).
1. Ukucushwa kwe-Electron:
– I-oksijini: 1s² 2s² 2p⁴ (ama-electron angu-8 esewonke)
– I-hydrogen: 1s¹ (i-electron eyodwa iyonke)
I-oksijini idinga amanye ama-electron amabili ukuze kufezwe ukucushwa kwe-octet (ama-electron angu-8 egobolondweni layo langaphandle), kuyilapho i-athomu ngayinye ye-hydrogen idinga i-electron eyodwa ukuze kufezwe ukucushwa kwe-duplet (ama-electron amabili egobolondweni le-K).
2. Ukwakheka Kwezibopho Ezihlanganisiwe:
– I-athomu ngayinye ye-hydrogen ihlanganyela i-electron eyodwa ne-athomu ye-Oxygen.
– I-oksijini ihlanganyela ama-electron amabili nama-athomu amabili e-hydrogen, elilodwa nge-athomu ngayinye.
Ngakho-ke, kwakheka izibopho ezimbili ze-covalent ku-molecule ye-H2O, eyodwa phakathi kwe-athomu ye-Oxygen ne-athomu ye-Hydrogen ngokulandelana.
umbuzo 2
Bhala isakhiwo sikaLewis se-molecule ye-methane (CH₄).
Ingxoxo:
I-Methane iqukethe i-athomu eyodwa yekhabhoni (C) kanye nama-athomu amane e-hydrogen (H).
1. Ukucushwa kwe-Electron:
– Ikhabhoni: 1s² 2s² 2p² (ama-electron ayi-6 esewonke)
– I-hydrogen: 1s¹ (i-electron eyodwa iyonke)
Ikhabhoni inama-electron amane e-valence (2s² 2p²), futhi idinga amanye ama-electron amane ukuze ifinyelele i-octet.
2. Ukwakheka Kwezibopho Ezihlanganisiwe:
– I-athomu ngayinye ye-hydrogen ihlanganyela i-electron eyodwa ne-athomu ye-Carbon.
– Ikhabhoni ihlanganyela ama-electron amane nama-athomu e-hydrogen amane, elilodwa nge-athomu ngayinye.
Isakhiwo sikaLewis se-methane simi kanje:
``
H
|
H – C – H
|
H
``
Ikhabhoni iphakathi nendawo enezibopho ezine ze-covalent eyodwa kuma-athomu amane e-hydrogen.
umbuzo 3
Thola isakhiwo sikaLewis kanye nesimo sama-molecule se-carbon dioxide (CO₂).
Ingxoxo:
I-carbon dioxide iqukethe i-athomu eyodwa yekhabhoni (C) kanye nama-athomu amabili e-oxygen (O).
1. Ukucushwa kwe-Electron:
– Ikhabhoni: 1s² 2s² 2p² (ama-electron ayi-6 esewonke)
– I-oksijini: 1s² 2s² 2p⁴ (ama-electron angu-8 esewonke)
Ikhabhoni inama-electron amane e-valence, kuyilapho i-athomu ngayinye ye-oxygen inayisithupha. Ikhabhoni idinga ama-electron amane engeziwe ukuze ithole i-octet, kuyilapho i-athomu ngayinye ye-oxygen idinga amabili engeziwe.
2. Ukwakheka Kwezibopho Ezihlanganisiwe:
– I-Carbon ihlanganyela ama-electron amabili ne-athomu ngayinye ye-Oxygen.
– Kwakhiwa izibopho ezimbili eziphindwe kabili ze-covalent phakathi kwe-Carbon kanye ne-Oxygen ngayinye.
Isakhiwo sikaLewis se-CO₂ simi kanje:
``
O = C = O
``
Isimo sama-molecule siqondile nge-engeli yesibopho engu-180°.
umbuzo 4
Bala inani eliphelele lama-electron e-valence bese udweba isakhiwo se-Lewis se-molecule ye-ammonia (NH₃).
Ingxoxo:
I-Amoniya iqukethe i-athomu eyodwa ye-nitrogen (N) kanye nama-athomu amathathu e-hydrogen (H).
1. Ukucushwa kwe-Electron:
– I-nitrogen: 1s² 2s² 2p³ (ama-electron angu-7 esewonke)
– I-hydrogen: 1s¹ (i-electron eyodwa iyonke)
I-nitrogen inama-electron amahlanu e-valence, idinga amanye ama-electron amathathu ukuze kube ne-octet.
2. Inani Eliphelele Lama-Electron e-Valence:
– I-nitrogen: ama-electron angu-5 e-valence.
– I-hydrogen (ama-athomu ama-3): ama-electron ama-3 (i-electron eyodwa nge-athomu).
Ama-electron e-valence aphelele = 5 + 3 = 8 ama-electron e-valence.
3. Ukwakheka Kwezibopho Ezihlanganisiwe:
– I-nitrogen yabelana nge-electron eyodwa ne-athomu ngayinye ye-hydrogen.
Isakhiwo sikaLewis se-NH₃ yilesi:
``
H
|
H – N – H
|
``
Futhi i-pair yama-electron akhululekile (i-lone pair) itholakala ku-nitrogen.
umbuzo 5
Dweba bese uchaza isakhiwo sikaLewis se-nitrate ion (NO₃⁻).
Ingxoxo:
I-nitrate ion iyinhlanganisela ye-polyatomic ene-nitrogen eyodwa (N) kanye nama-oxygen amathathu (O), kanye ne-negative charge.
1. Ukucushwa kwe-Electron:
– I-nitrogen: 1s² 2s² 2p³ (ama-electron angu-7 esewonke)
– I-oksijini: 1s² 2s² 2p⁴ (ama-electron angu-8 esewonke)
I-nitrogen inama-electron amahlanu e-valence, kanti i-oxygen ngayinye inama-electron ayisithupha e-valence.
2. Inani Eliphelele Lama-Electron e-Valence:
– I-nitrogen: ama-electron ama-5.
– I-oksijini (ama-athomu angu-3): ama-electron angu-18 (ama-electron angu-6 nge-athomu ngayinye).
– Okwengeziwe ngenxa yama-ion angalungile: i-electron eyi-1.
Ama-electron e-valence aphelele = 5 + 18 + 1 = ama-electron e-valence angu-24.
3. Ukwakhiwa Kwezibopho Ezihlanganisiwe Nokulungiswa Kwezakhiwo ZikaLewis:
– I-nitrogen yakha isibopho esiphindwe kabili nenye yama-athomu e-oxygen kanye nesibopho esisodwa namanye ama-athomu amabili e-oxygen.
– Ukusatshalaliswa okulinganayo kweshaja engalungile phakathi kwama-athomu amabili e-oxygen anezibopho ezilodwa kuhilela ukuhlangana kwe-resonance.
Isakhiwo sikaLewis se-NO₃⁻ sithi:
``
O
/
VULIWE=O
``
Kodwa kumele kufakwe uphawu lokuzwakala kwe-resonance ukuchaza ukuhlukaniswa kwama-electron.
Isiphetho
Ukubopha nge-covalent kuwumqondo oyisisekelo kumakhemikhali, lapho ama-athomu abelana ngama-electron ukuze kufezwe ukuzinza. Ukuqonda ukuthi ungadweba kanjani izakhiwo zikaLewis, ubale ama-electron e-valence, futhi unqume ukuma kwama-molecule kuyikhono elibalulekile lokuqonda okujulile izinqubo zamakhemikhali. Ngezibonelo ezingenhla, kunethemba lokuthi abafundi bazothola ukuqonda okungcono kokwakheka kanye nezici zezibopho ze-covalent.
