Njikọ kemịkal

Njikọ kemịkal bụ ihe na-adịgide adịgide n'etiti atọm ma ọ bụ ion nke na-eme ka e nwee ike ịmepụta molekụl, kristal, na ihe ndị ọzọ. Njikọ ahụ nwere ike ịpụta site na ike electrostatic n'etiti ion ndị na-akwụ ụgwọ dị ka njikọ ion, ma ọ bụ site na ịkekọrịta electrons dị ka njikọ covalent. Ike nke njikọ kemịkal dịgasị iche iche; enwere "njikọ siri ike" ma ọ bụ "njikọta isi" dịka njikọ covalent, ionic na metallic, na "njikụ na-adịghị ike" maọ bụ "njikunọ nke abụọ" dịka mmekọrịta dipole-dipole, ike mgbasa nke London, na njikọ hydrogen.

Ebe ọ bụ na ụgwọ eletrik dị iche iche na-adọta, electrons na-adịghị mma gbara nucleus gburugburu na protons na-adọrọ mmasị n'ime nucleus na-adọkpụ ibe ha. Electrons ndị e kewara n'etiti nuclei abụọ ga-adọta ha abụọ. "Ntinye aka nke quantum mechanical wavefunction" na-eme ka nucleus abụọ kwụsie ike (lee Theories of chemical bonding).^[1] Njikọ nuclei na-ejikọta ọnụ na-anọgide na-enwe ebe kachasị mma (ebe dị anya) na-eme ka mmetụta na-adọrọ mmasị na nke na-asọ oyi bụrụ nke a kọwara n'ụzọ dị ukwuu site na quantum theory.^[2]

Atọ ndị dị na molecules, crystals, metals na ụdị ihe ndị ọzọ na-ejikọta ọnụ site na njikọ kemịkal, nke na-ekpebi ọdịdị na njirimara nke ihe.

Enwere ike ịkọwa njikọ niile site na quantum theory, mana, n'omume, iwu dị mfe na echiche ndị ọzọ na-enye ndị na-emepụta kemịkal ohere ịkọwa ike, ntụziaka, na polarity nke njikọ.^[3] Iwu octet na echiche VSEPR bụ ihe atụ. Echiche ndị ọzọ dị mgbagwoju anya bụ echiche valence bond, nke gụnyere ngwakọta^[4] orbital na resonance, na echiche orbital nke na-agụnye njikọta nke atomic orbitals na echiche nke ligand field.^[5] A na-eji electrostatics akọwa polarities bond na mmetụta ha nwere na kemịkal.

Nchịkọta nke ụdị njikọ kemịkal

Njikọ kemịkal bụ ihe na-adọrọ mmasị n'etiti atọm. Enwere ike ịhụ mmasị a dị ka nsonaazụ nke omume dị iche iche nke electrons nke atọm. Omume ndị a na-agwakọta n'etiti onwe ha n'enweghị nsogbu n'ọnọdụ dị iche iche, nke mere na enweghị akara doro anya a ga-etinye n'etiti ha. Otú ọ dị, ọ ka bara uru ma bụrụ omenala iji mee ka ọdịiche dị n'etiti ụdị njikọ dị iche iche, nke na-akpata njirimara dị iche iche nke ihe dị nro.

N'echiche kachasị mfe nke njikọ covalent, a na-adọta otu ma ọ bụ karịa electrons (nke na-abụkarị electrons abụọ) n'ime oghere dị n'etiti atọm abụọ. A na-ewepụta ike site na mmepụta bond.^[6] Nke a abụghị n'ihi mbelata nke ike nwere ike, n'ihi na ihe na-adọrọ mmasị nke electrons abụọ na protons abụọ na-egbochi site na electron-electron na proton-proton repulsions. Kama nke ahụ, ntọhapụ nke ike (ya mere nkwụsi ike nke njikọ ahụ) na-esite na mbelata nke ike kinetic n'ihi na electrons nọ na mpaghara a na-ekesa (ya bụ ogologo oge nke Broglie wavelength) ma e jiri ya tụnyere electron ọ bụla na-ejide nso na nucleus ya.^[7] Njikọ ndị a dị n'etiti atọm abụọ a na-ahụ anya ma nwee ntụziaka na mbara igwe, na-enye ohere igosi ha dị ka otu ahịrị njikọ n'etiti atoms na eserese, ma ọ bụ mepụta dị ka osisi n'etiti okirikiri na ụdị.

Na njikọ covalent polar, otu ma ọ bụ karịa electrons na-ekerịta n'ụzọ na-ahaghị nhata n'etiti nucleus abụọ. Njikọ Covalent na-akpatakarị n'ịmepụta obere nchịkọta nke atọm jikọtara ọnụ a na-akpọ molecules, nke na solids na mmiri na-ejikọta na molecules ndị ọzọ site na ike ndị na-adịghị ike karịa njikọ covalent nke na-ejide molecules n'ime. Njikọ intermolecular ndị dị otú ahụ na-adịghị ike na-enye ihe ndị dị ndụ, dị ka waxes na mmanụ, àgwà ha dị nro, na ebe ha na-agbaze ala (na mmiri, mkpụrụ ndụ ga-akwụsị mmekọrịta kachasị mma ma ọ bụ nke na-agagharị na ibe ha). Mgbe njikọ covalent na-ejikọta ogologo agbụ nke atọm n'ime nnukwu molekụl, Otú ọ dị (dị ka na polymer dị ka naịlọn), ma ọ bụ mgbe njikọ covalents na-agbasa na netwọk site na ihe siri ike nke na-enweghị mkpụrụ ndụ dị iche iche (dị ka diamond ma ọ bụ quartz ma ọ bụ silicate mineral n'ọtụtụ ụdị nkume) mgbe ahụ ihe ndị na-esi ike ma sie ike, ọ dịkarịa ala na ntụziaka nke ziri ezi na netwọk nke njikọ covalente.^[8] Ọzọkwa, ebe agbaze nke polymer na netwọk ndị dị otú ahụ na-abawanye nke ukwuu.

N'echiche dị mfe nke njikọ <i id="mwYg">ionic</i>, ejikọtaghị njikọ electron ma ọlị, kama a na-ebufe ya. N'ụdị njikọ a, okirikiri atọm dị n'èzí nke otu atọm nwere oghere nke na-enye ohere ịgbakwunye otu ma ọ bụ karịa electrons. Electrons ndị a agbakwunyere ọhụrụ nwere ike ịnọ n'ọnọdụ ike dị ala (nke dị nso na ụgwọ nuklia) karịa ka ha nwere na atọm dị iche. Ya mere, otu nucleus na-enye ọnọdụ ejikọrọ nke ọma na electron karịa nucleus ọzọ, na nsonaazụ na otu atọm nwere ike ịnyefe electron na nke ọzọ. Mbufe a na-eme ka otu atọm were ụgwọ dị mma, na nke ọzọ were ụgwọ dị njọ. Njikọ ahụ na-esite na electrostatic attraction n'etiti positive na negative charged ion. Enwere ike ịhụ njikọ Ionic dị ka ihe atụ siri ike nke polarization na njikọ covalent. Ọtụtụ mgbe, njikọ ndị dị otú ahụ enweghị ntụziaka pụrụ iche na mbara igwe, ebe ọ bụ na ha na-esite na ịdọrọ mmasị electrostatic nke ion ọ bụla na ion niile gbara ha gburugburu. Njikọ ion siri ike (ya mere ihe ionic chọrọ okpomọkụ dị elu iji gbazee) kamakwa ọ na-emebi emebi, ebe ọ bụ na ike dị n'etiti ion dị mkpụmkpụ ma ọ naghị eme ka ọ dị mfe ịkpụkọta oghere na mgbawa. Ụdị njikọ a na-ebute njirimara anụ ahụ nke kristal nke nnu mineral, dị ka nnu tebụl.

Ụdị njikọ a na-ekwukarị okwu ya bụ njikọ <i id="mwaA">ígwè</i>. N'ụdị njikọ a, atọm ọ bụla dị na ígwè na-enye otu ma ọ bụ karịa electrons na "oké osimiri" nke electrons nke bi n'etiti ọtụtụ atọm ígwè. N'oké osimiri a, electron ọ bụla nweere onwe ya (site n'ike nke ọdịdị ebili mmiri ya) ka ejikọta ya na ọtụtụ atọm n'otu oge. Njikọ ahụ na-apụta n'ihi na atọm ọla na-aghọ nke ọma n'ihi ọnwụ nke electrons ha ebe electrons na-anọgide na-adọta ọtụtụ atọm, na-enweghị akụkụ nke atọm ọ bụla. Enwere ike ịhụ njikọ metallic dị ka ihe atụ siri ike nke deocalization nke electrons n'elu nnukwu usoro nke njikọ covalent, nke atọm ọ bụla na-ekere òkè na ya. Ụdị njikọ a na-esikarị ike (nke na-akpata ike nke ọla). Otú ọ dị, njikọ ígwè dị n'otu karịa ụdị ndị ọzọ, ya mere ha na-enye ohere ka kristal ígwè mebie ngwa ngwa, n'ihi na ha nwere atọm ndị na-adọta ibe ha, mana ọ bụghị n'ụzọ ọ bụla. Nke a na-eme ka ọla na-agbanwe agbanwe. Igwe ojii nke electrons na njikọ ígwè na-akpata ezigbo conductivity eletrik na okpomọkụ nke ọla, yana ìhè ha na-egbuke egbuke nke na-egosipụta ọtụtụ ugboro nke ìhè ọcha.

Nkọwa mbụ banyere ọdịdị nke njikọ kemịkal, site na mmalite narị afọ nke iri na abụọ, na-eche na ụdị kemịkal ụfọdụ sonyeere ụdị kemịl. N'afọ 1704, Sir Isaac Newton kọwara echiche njikọ atọm ya, na "Query 31" nke Opticks ya, ebe atọm na-ejikọta ibe ha site na "ike". N'ụzọ doro anya, mgbe ọ kwetara na echiche dị iche iche na-ewu ewu n'oge ahụ, nke otu esi eche echiche ka atọm jikọta ibe ha, ya bụ, "atọm ejikọtara", "na-ejikọta ọnụ site na izu ike", ma ọ bụ "na-agbakọta ọnụ site n'ịgba izu", Newton na-ekwu na ọ ga-ahọrọ site na ịdị n'otu ha, na "ihe ndị na-adọta ibe ha site na ike ụfọdụ, nke na mmetụ ozugbo siri ike nke ukwuu, na obere oge na-arụ ọrụ kemịkal, ma na-eru nso nso na-arụsi anya site na ụmụ irighiri ihe ndị ahụ na mmetụta ọ bụla".

N'afọ 1819, na-esote nchọpụta nke voltaic pile, Jöns Jakob Berzelius mepụtara echiche nke njikọta kemịkal na-emesi ihe odide electronegative na electropositive nke atọm jikọtara ike. Ka ọ na-erule n'etiti narị afọ nke 19, Edward Frankland, F.A. Kekulé, A.S. Couper, Alexander Butlerov, na Hermann Kolbe, na-ewulite n'echiche nke ndị na-eme ihe ike, mepụtara echiche nke valency, nke a na-akpọ "ike njikọta", nke a na'ime ya sonyeere ihe ndị dị n'ihi mmasị nke ọma na nke ọjọọ. N'afọ 1904, Richard Abegg tụrụ aro iwu ya na ọdịiche dị n'etiti valencies kachasị elu na nke kacha nta nke otu ihe na-abụkarị asatọ. N'oge a, valency ka bụ ọnụọgụ nke dabeere naanị na kemịkal.

Otú ọ dị, ọdịdị nke atọm ahụ bịara doo anya na nchọpụta Ernest Rutherford nke 1911 nke nucleus atọm gbara gburugburu nke ọ hotara Nagaoka jụrụ ihe nlereanya Thomson n'ihi na ebubo ndị ọzọ enweghị ike ịghọta. N'afọ 1904, Nagaoka chepụtara ihe nlereanya ọzọ nke atọm nke ebe ọtụtụ electrons na-agbagharị agbagharị gbara etiti ya gburugburu, n'ụzọ Saturn na mgbaaka ya.^[9]

Echiche nke njikọ kemịkal

Na njedebe (nke na-agaghị ekwe omume) nke njikọ ion "dị ọcha", electrons dị n'otu n'ime atọm abụọ dị na njikọ ahụ. Enwere ike ịghọta njikọ ndị dị otú ahụ site na physics oge ochie. Ike dị n'etiti atọm na-eji isotropic continuum electrostatic potentials mara. Nnukwu ha [nkọwa dị mkpa] dị n'ụzọ dị mfe na ọdịiche dị na ụgwọ. [ntụgharị dị mkpa]

Covalent bonds na-aghọta nke ọma site na valence bond (VB) ma ọ bụ molecular orbital (MO). Enwere ike ịghọta njirimara nke atọm ndị metụtara site na iji echiche ndị dị ka ọnụọgụ oxidation, ụgwọ iwu, na electronegativity. A naghị enye ọnụọgụ electron n'ime njikọ na atọm ọ bụla, kama a na-ewepụ ya n'etiti atọm. Na valence bond theory, a na-eche na njikọta dị ka nke a na-ewulite site na electron abụọ nke atọm abụọ na-ejikọta ma na-ekerịta site na mkpuchi nke atomic orbitals. Echiche nke ngwakọta orbital na resonance na-eme ka echiche a dị mkpa nke njikọ electron abụọ dịkwuo elu. N'echiche nke orbital nke mkpụrụ ndụ, a na-ele njikọ anya dị ka nke a na-ewepụ ma kewaa na orbitals nke na-agbasa n'ime mkpụrụ ndụ ahụ ma na-eme ka ọ kwekọọ na njirimara ya, nke a na'ozuzu site n'ịtụle njikọta nke atomic orbitals (LCAO). Valence bond theory bụ ihe doro anya karịa na kemịkal site na ịbụ ebe dị, na-enye ohere ka a lekwasị anya n'akụkụ nke molecule na-enwe mgbanwe kemịkal. N'ụzọ dị iche, mkpụrụ ndụ orbitals bụ "okike" karịa site n'echiche nke quantum mechanical, na ike orbital dị ịrịba ama n'ụzọ anụ ahụ ma jikọta ya na ike ionization nke nnwale site na fotoelectron spectroscopy. N'ihi ya, a na-elekarị echiche nke njikọ valence na echiche nke orbital molecular anya dị ka usoro asọmpi ma na-akwado nke na-enye nghọta dị iche iche banyere usoro kemịkal. Dị ka ụzọ maka usoro nhazi eletrọniki, ma usoro MO na VB nwere ike inye approximations na ọkwa ọ bụla achọrọ nke izi ezi, ọ dịkarịa ala na ụkpụrụ. Otú ọ dị, na ọkwa dị ala, approximations dị iche, na otu ụzọ nwere ike ịdị mma maka ngụkọta metụtara otu usoro ma ọ bụ onwunwe karịa nke ọzọ.

N'adịghị ka ike Coulombic na-agba gburugburu na njikọ ionic dị ọcha, njikọ covalent na-eduzi ma na-adọkpụ. A na-ekewapụta ihe ndị a dabere na nhazi ha n'ihe gbasara mbara igwe dị ka njikọ sigma na njikọ pi. N'ozuzu, atọm na-emepụta njikọ ndị dị n'etiti ionic na covalent, dabere na electronegativity nke atọm ndị metụtara. A maara njikọ nke ụdị a dị ka njikọ polar covalent.

Ihe odide

↑ Levine (2020-09-29). "Clarifying the quantum mechanical origin of the covalent chemical bond". Nature Communications 11 (1). DOI:10.1038/s41467-020-18670-8. ISSN 2041-1723. PMID 32994392.
↑ Hund (1928). "Zur Deutung der Molekelspektren. IV" (in de). Zeitschrift für Physik 51 (11–12): 759–795. DOI:10.1007/BF01400239. ISSN 1434-6001.
↑ Frenking (2007-01-15). "Unicorns in the world of chemical bonding models" (in en). Journal of Computational Chemistry 28 (1): 15–24. DOI:10.1002/jcc.20543. PMID 17109434.
↑ Jensen (1999). Introduction to Computational Chemistry. John Wiley and Sons. ISBN 978-0-471-98425-2.
↑ Pauling (1960). "The Concept of Resonance", The Nature of the Chemical Bond – An Introduction to Modern Structural Chemistry, 3rd, Cornell University Press, 10–13. ISBN 978-0801403330.
↑ Housecroft (2005). Inorganic Chemistry, 2nd, Pearson Prentice-Hal. ISBN 0130-39913-2.
↑ Rioux, F. (2001). "The Covalent Bond in H₂". The Chemical Educator 6 (5): 288–290. DOI:10.1007/s00897010509a.
↑ Housecroft (2005). Inorganic Chemistry, 2nd, Pearson Prentice-Hal. ISBN 0130-39913-2.
↑ B. Bryson (2003). A Short History of Nearly Everything. Broadway Books. ISBN 0-7679-0817-1.

Njikọ mpụga

W. Locke (1997). Nkwupụta nke Molecular Orbital Theory. E nwetara ya na May 18, 2005.
Carl R. Nave (2005). HyperPhysics. E nwetara ya na May 18, 2005.
Linus Pauling na ọdịdị nke njikọ kemịkal: Akụkọ ihe mere eme. E nwetara ya na February 29, 2008.

[Levine_Head-Gordon_2020_p.-1] Levine (2020-09-29). "Clarifying the quantum mechanical origin of the covalent chemical bond". Nature Communications 11 (1). DOI:10.1038/s41467-020-18670-8. ISSN 2041-1723. PMID 32994392.

[2] Hund (1928). "Zur Deutung der Molekelspektren. IV" (in de). Zeitschrift für Physik 51 (11–12): 759–795. DOI:10.1007/BF01400239. ISSN 1434-6001.

[3] Frenking (2007-01-15). "Unicorns in the world of chemical bonding models" (in en). Journal of Computational Chemistry 28 (1): 15–24. DOI:10.1002/jcc.20543. PMID 17109434.

[Frank-4] Jensen (1999). Introduction to Computational Chemistry. John Wiley and Sons. ISBN 978-0-471-98425-2.

[Pauling-5] Pauling (1960). "The Concept of Resonance", The Nature of the Chemical Bond – An Introduction to Modern Structural Chemistry, 3rd, Cornell University Press, 10–13. ISBN 978-0801403330.

[6] Housecroft (2005). Inorganic Chemistry, 2nd, Pearson Prentice-Hal. ISBN 0130-39913-2.

[7] Rioux, F. (2001). "The Covalent Bond in H₂". The Chemical Educator 6 (5): 288–290. DOI:10.1007/s00897010509a.

[8] Housecroft (2005). Inorganic Chemistry, 2nd, Pearson Prentice-Hal. ISBN 0130-39913-2.

[9] B. Bryson (2003). A Short History of Nearly Everything. Broadway Books. ISBN 0-7679-0817-1.

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