Zitsanzo za Mafunso Okhudza Maonekedwe a Ma Molecular
Pegantar
Chemistry ndi kuphunzira za khalidwe la zinthu ndi kusintha komwe kumachitika. Lingaliro limodzi lofunika mu chemistry ndikumvetsetsa mawonekedwe a mamolekyu. Mawonekedwe a mamolekyu amakhudza mawonekedwe a thupi ndi mankhwala a zinthu, monga mfundo yosungunuka, mfundo yowira, ndi kuthamanga kwa nthunzi. Mawonekedwe a mamolekyu nawonso amatenga gawo lofunikira pakuzindikira momwe mankhwala amachitira zomwe zimachitika m'zinthuzo. Chiphunzitso chomwe chimagwiritsidwa ntchito kwambiri pofotokoza mawonekedwe a mamolekyu ndi chiphunzitso cha VSEPR (Valence Shell Electron Pair Repulsion). M'nkhaniyi, tikambirana zitsanzo zingapo za mavuto okhudzana ndi mawonekedwe a mamolekyu ndi momwe chiphunzitso cha VSEPR chingagwiritsidwire ntchito powathetsa.
Chiphunzitso cha VSEPR
Chiphunzitso cha VSEPR ndi chiphunzitso chomwe chimagwiritsidwa ntchito kudziwa mawonekedwe a mamolekyu kutengera kugwedezeka kwa ma elekitironi awiriawiri kuzungulira atomu yapakati. Malinga ndi chiphunzitsochi, ma elekitironi awiriawiri adzadzikonza okha mwanjira yoti kugwedezeka pakati pawo kuchepe. Izi zimapangitsa molekyuluyo kutenga mawonekedwe enieni, odziwikiratu. Ma elekitironi awiriawiri awa akuphatikizapo ma elekitironi awiriawiri ogwirizana (BEPs) ndi ma elekitironi awiriawiri (LOPs).
Zina mwa mitundu ya mamolekyu yomwe imapangidwa nthawi zambiri ndi:
1. Mzere
2. Mapulani Atatu
3. Tetrahedral
4. Trigonal Bipyramidal
5. Octahedral
6. Wopindika (wopindika)
7. Masewero
8. Wooneka ngati T
9. Pulani Yaikulu
10. Piramidi Yaikulu
Kenako, tiyeni tiwone zitsanzo za mafunso ndi zokambirana zawo.
Chitsanzo Funso 1: Kudziwa Mawonekedwe a Mamolekyulu a CH4
Funso:
Dziwani mawonekedwe a molekyulu ya methane (CH4) pogwiritsa ntchito chiphunzitso cha VSEPR.
Kukambirana:
1. Dziwani Kapangidwe ka Lewis:
– Atomu yapakati: C (kaboni)
– Mpweya uli ndi ma electron anayi a valence.
– Hydrojeni iliyonse ili ndi elekitironi imodzi ya valensi.
– Ma electron onse a valensi = 4 (C) + 4 x 1 (H) = ma electron 8 a valensi.
Kapangidwe ka Lewis ka CH4 kamasonyeza kaboni pakati pomwe maatomu anayi a haidrojeni amapanga ma bond amodzi (sigma) ku atomu ya kaboni. Palibe ma elekitironi awiriawiri okha pa atomu ya kaboni.
2. Kuwerengera Ma Electron Pairs:
– PEI: Pali ma bond anayi, onse ndi ma bonding electron pairs.
– PEB: Palibe ma electron awiriawiri okha.
3. Kuzindikira Maonekedwe a Mamolekyu:
– Ndi 4 PEI ndi 0 PEB yonse, kugawa kwa ma elekitironi kuzungulira atomu yapakati kudzatenga mawonekedwe omwe amachepetsa kukana.
– Fomu yomwe ili ndi kufalikira kwakutali kwambiri ndi Tetrahedral.
Chifukwa chake, mawonekedwe a molekyulu ya CH4 ndi tetrahedral yokhala ndi ngodya yolumikizira ya madigiri pafupifupi 109.5.
Chitsanzo Funso 2: Kudziwa Maonekedwe a Molekyulu a NH3
Funso:
Dziwani mawonekedwe a molekyulu a ammonia (NH3) pogwiritsa ntchito chiphunzitso cha VSEPR.
Kukambirana:
1. Dziwani Kapangidwe ka Lewis:
– Atomu yapakati: N (nayitrogeni).
- Nayitrogeni ili ndi ma electron 5 a valence.
– Hydrojeni iliyonse ili ndi elekitironi imodzi ya valensi.
– Ma electron onse a valensi = 5 (N) + 3 x 1 (H) = ma electron 8 a valensi.
Kapangidwe ka Lewis ka NH3 kamasonyeza nayitrogeni pakati ndi maatomu atatu a haidrojeni omwe amapanga ma bond amodzi (sigma) ndi atomu ya nayitrogeni ndi ma elekitironi awiriawiri pa nayitrogeni.
2. Kuwerengera Ma Electron Pairs:
– PEI: Pali ma bond atatu, onse ndi ma bonding electron pairs.
– PEB: Pali awiriawiri a elekitironi imodzi yokha.
3. Kuzindikira Maonekedwe a Mamolekyu:
– Ndi 3 PEI ndi 1 PEB yonse, kugawa kwa ma elekitironi kuzungulira atomu yapakati kudzatenga mawonekedwe omwe amachepetsa kukana.
– Kapangidwe kake koyenera ndi Trigonal Pyramidal.
Chifukwa chake, mawonekedwe a molekyulu ya NH3 ndi trigonal pyramidal yokhala ndi ngodya yolumikizira yochepera madigiri 109.5 chifukwa cha kugwedezeka kwa awiri amphamvu a elekitironi.
Chitsanzo Funso 3: Kudziwa Maonekedwe a Mamolekyulu a H2O
Funso:
Dziwani mawonekedwe a molekyulu yamadzi (H2O) pogwiritsa ntchito chiphunzitso cha VSEPR.
Kukambirana:
1. Dziwani Kapangidwe ka Lewis:
– Atomu yapakati: O (mpweya).
– Mpweya wa okosijeni uli ndi ma electron 6 a valence.
– Hydrojeni iliyonse ili ndi elekitironi imodzi ya valensi.
– Ma electron onse a valensi = 6 (O) + 2 x 1 (H) = ma electron 8 a valensi.
Kapangidwe ka Lewis ka H2O kamasonyeza mpweya pakati ndi maatomu awiri a haidrojeni omwe amapanga ma bond amodzi (sigma) ndi atomu ya mpweya ndi ma elekitironi awiri okha pa mpweya.
2. Kuwerengera Ma Electron Pairs:
– PEI: Pali ma bond atatu, onse ndi ma bonding electron pairs.
– PEB: Pali awiriawiri a elekitironi imodzi yokha.
3. Kuzindikira Maonekedwe a Mamolekyu:
– Ndi 2 PEI ndi 2 PEB yonse, kugawa kwa ma elekitironi kuzungulira atomu yapakati kudzatenga mawonekedwe omwe amachepetsa kukana.
– Kapangidwe kake koyenera ndi Bent.
Kotero, mawonekedwe a molekyulu ya H2O amapindika ndi ngodya yolumikizana ya madigiri pafupifupi 104.5.
Chitsanzo Funso 4: Kudziwa Mawonekedwe a Molecular a PCl5
Funso:
Dziwani mawonekedwe a phosphorous pentachloride (PCl5) pogwiritsa ntchito chiphunzitso cha VSEPR.
Kukambirana:
1. Dziwani Kapangidwe ka Lewis:
– Atomu yapakati: P (phosphorous).
- Phosphorus ili ndi ma electron 5 a valence.
– Chlorine iliyonse ili ndi ma electron 7 a valence.
– Ma electron onse a valensi = 5 (P) + 5 x 7 (Cl) = ma electron 40 a valensi.
Kapangidwe ka Lewis ka PCl5 kamasonyeza phosphorous pakati ndi maatomu asanu a chlorine omwe amapanga ma bond amodzi (sigma) ndi atomu ya phosphorous. Palibe ma elekitironi awiriawiri pa phosphorous.
2. Kuwerengera Ma Electron Pairs:
– PEI: Pali ma bond atatu, onse ndi ma bonding electron pairs.
– PEB: Palibe ma electron awiriawiri okha.
3. Kuzindikira Maonekedwe a Mamolekyu:
– Ndi 5 PEI ndi 0 PEB yonse, kugawa kwa ma elekitironi kuzungulira atomu yapakati kudzatenga mawonekedwe omwe amachepetsa kukana.
– Kapangidwe kake koyenera ndi Trigonal Bipyramidal.
Chifukwa chake, mawonekedwe a molekyulu ya PCl5 ndi trigonal bipyramidal yokhala ndi ma angles omangirira a 90° ndi 120°.
Chitsanzo Funso 5: Kudziwa Mawonekedwe a Ma Molekyulu a SF6
Funso:
Dziwani mawonekedwe a molekyulu a sulfure hexafluoride (SF6) pogwiritsa ntchito chiphunzitso cha VSEPR.
Kukambirana:
1. Dziwani Kapangidwe ka Lewis:
– Atomu yapakati: S (sulfure).
– Sulfure ili ndi ma electron 6 a valence.
– Fluorine iliyonse ili ndi ma electron 7 a valence.
– Ma electron onse a valensi = 6 (S) + 6 x 7 (F) = ma electron 48 a valensi.
Kapangidwe ka Lewis ka SF6 kamasonyeza sulfure pakati ndi maatomu asanu ndi limodzi a fluorine omwe amapanga ma bond amodzi (sigma) ndi atomu ya sulfure. Palibe ma elekitironi awiriawiri pa sulfure.
2. Kuwerengera Ma Electron Pairs:
– PEI: Pali ma bond atatu, onse ndi ma bonding electron pairs.
– PEB: Palibe ma electron awiriawiri okha.
3. Kuzindikira Maonekedwe a Mamolekyu:
– Ndi 6 PEI ndi 0 PEB yonse, kugawa kwa ma elekitironi kuzungulira atomu yapakati kudzatenga mawonekedwe omwe amachepetsa kukana.
– Kapangidwe kake koyenera ndi Octahedral.
Kotero, mawonekedwe a molekyulu ya SF6 ndi octahedral yokhala ndi ngodya yolumikizira ya 90°.
Mapeto
Kumvetsetsa mawonekedwe a molekyulu ndikofunikira kwambiri pofotokoza zambiri za mankhwala ndi thupi la chinthu. Chiphunzitso cha VSEPR chimapereka njira yothandiza yodziwira momwe chimagwirira ntchito kutengera kuwerengera kwa ma bonding ndi ma single pairs. Mu zitsanzo zonse zomwe zafotokozedwa, njirayi imaphatikizapo kudziwa kapangidwe ka Lewis, kuwerengera ma electron pairs, ndikuzindikira mawonekedwe oyenera kwambiri a molekyulu. Ndi kuchita pafupipafupi, aliyense akhoza kukhala waluso pogwiritsa ntchito chiphunzitso cha VSEPR kuti adziwe mawonekedwe a molekyulu.
