Cov qauv spatial ntawm cov molecules ntawm inorganic thiab organic tshuaj yog qhov tseem ceeb hauv kev piav qhia lawv cov tshuaj thiab lub cev. Yog hais tias peb xav txog ib yam khoom raws li ib txheej ntawm cov ntawv thiab cov lej ntawm daim ntawv, nws tsis yog ib txwm ua tau los mus rau qhov yog. Txhawm rau piav qhia ntau yam tshwm sim, tshwj xeeb tshaj yog cov cuam tshuam nrog cov organic chemistry, nws yog ib qho tsim nyog yuav tsum paub cov qauv stereometric ntawm cov molecule.
Dab tsi yog stereometric
Stereometry yog ib ceg ntawm chemistry uas piav qhia txog cov khoom ntawm cov molecules ntawm ib yam khoom raws li nws cov qauv. Ntxiv mus, lub spatial sawv cev ntawm molecules plays lub luag hauj lwm tseem ceeb ntawm no, txij li thaum Nws yog tus yuam sij rau ntau qhov tshwm sim bioorganic.
Stereometry yog txheej txheem ntawm cov cai uas yuav luag txhua lub molecule tuaj yeem sawv cev rau hauv daim ntawv ntim. Qhov tsis zoo ntawm tag nrho cov qauv sau rau ntawm daim ntawv tsis tu ncua yog nws tsis muaj peev xwm nthuav tawm tag nrho cov npe ntawm cov khoom hauv qab kev kawm.
Ib qho piv txwv yuav yog fumaric acid, uas yog nyob rau hauv chav kawm dibasic. Nws tsis zoo soluble hauv dej,tshuaj lom thiab tuaj yeem pom hauv qhov xwm txheej. Txawm li cas los xij, yog tias koj hloov qhov kev npaj ntawm cov pab pawg COOH, koj tuaj yeem tau txais cov khoom sib txawv kiag li - maleic acid. Nws yog ib qho yooj yim soluble nyob rau hauv dej, tsuas yog muab tau artificially, thiab yog txaus ntshai rau tib neeg vim nws cov yam ntxwv lom.
Vant Hoff's stereochemical theory
Nyob rau xyoo pua 19th, M. Butlerov cov tswv yim hais txog lub tiaj tus qauv ntawm ib qho molecule tsis tuaj yeem piav qhia ntau yam khoom ntawm cov khoom, tshwj xeeb tshaj yog cov organics. Qhov no yog lub impetus rau van't Hoff los sau cov hauj lwm "Chemistry nyob rau hauv qhov chaw", nyob rau hauv uas nws supplemented lub tswv yim ntawm M. Butlerov nrog nws cov kev tshawb fawb nyob rau hauv lub cheeb tsam no. Nws tau qhia txog lub tswv yim ntawm cov qauv spatial ntawm molecules, thiab kuj piav qhia txog qhov tseem ceeb ntawm nws qhov kev tshawb pom rau kev tshawb fawb tshuaj.
Yog li, muaj peb hom lactic acid tau ua pov thawj: nqaij-lactic, dextrorotatory thiab fermented lactic acid. Ntawm ib daim ntawv rau txhua yam ntawm cov khoom no, cov qauv qauv yuav zoo ib yam, tab sis cov qauv spatial ntawm cov molecules piav qhia qhov tshwm sim no.
Qhov tshwm sim ntawm Van't Hoff txoj kev xav stereochemical yog qhov pov thawj ntawm qhov tseeb tias carbon atom tsis tiaj tus, vim nws plaub daim ntawv cog lus valence ntsib cov vertices ntawm ib qho kev xav tetrahedron.
Pyramidal spatial qauv ntawm cov organic molecules
Raws li qhov kev tshawb pom ntawm van't Hoff thiab nws cov kev tshawb fawb, txhua cov pa roj carbon monoxide nyob rau hauv cov pob txha ntawm cov organic teeb meem tuaj yeem sawv cev ua tetrahedron. Yog li pebpeb tuaj yeem xav txog 4 qhov tshwm sim ntawm kev tsim cov C-C daim ntawv cog lus thiab piav qhia cov qauv ntawm cov molecules.
thawj rooj plaub yog thaum cov molecule yog ib qho carbon atom uas tsim 4 daim ntawv cog lus nrog hydrogen protons. Cov qauv spatial ntawm methane molecules yuav luag tag rov qab cov ntsiab lus ntawm tetrahedron, txawm li cas los xij, lub kaum sab xis ntawm daim ntawv cog lus tau hloov me ntsis vim muaj kev cuam tshuam ntawm hydrogen atoms.
Kev tsim ntawm ib qho tshuaj C-C daim ntawv cog lus tuaj yeem sawv cev ua ob lub pyramids, uas yog sib cuam tshuam los ntawm ib qho vertex. Los ntawm xws li kev tsim kho ntawm cov molecule, nws tuaj yeem pom tias cov tetrahedra tuaj yeem tig ib ncig ntawm lawv cov axis thiab hloov txoj hauj lwm ywj pheej. Yog tias peb xav txog cov txheej txheem no siv cov piv txwv ntawm ethane molecule, cov pa roj carbon monoxide hauv cov pob txha muaj peev xwm tig tau tiag tiag. Txawm li cas los xij, ntawm ob txoj haujlwm yam ntxwv, kev nyiam yog muab rau qhov muaj txiaj ntsig zoo, thaum cov hydrogens hauv Newman qhov projection tsis sib tshooj.
Cov qauv spatial ntawm ethylene molecule yog ib qho piv txwv ntawm qhov thib peb variant ntawm kev tsim ntawm C-C bonds, thaum ob lub tetrahedra muaj ib lub ntsej muag, i.e. sib tshuam ntawm ob qhov chaw nyob ib sab. Nws paub tseeb tias vim yog txoj haujlwm stereometric ntawm cov molecule, kev txav ntawm cov pa roj carbon atoms txheeb ze rau nws cov axis yog qhov nyuaj, vim tias yuav tsum tau rhuav ib qho ntawm cov kev sib txuas. Ntawm qhov tod tes, kev tsim ntawm cis- thiab trans-isomers ntawm cov khoom ua tau, txij li thaum ob lub dawb radicals los ntawm txhua cov pa roj carbon monoxide tuaj yeem ua iav los yog crisscrossed.
Cis- thiab hloov pauv ntawm cov molecule piav qhia txog qhov muaj nyob ntawm fumaric thiab txiv neejkua qaub. Ob daim ntawv cog lus yog tsim los ntawm cov pa roj carbon atom hauv cov molecules, thiab lawv txhua tus muaj ib lub atom hydrogen thiab ib pawg COOH.
Cov ntaub ntawv kawg, uas qhia txog cov qauv spatial ntawm cov molecules, tuaj yeem sawv cev los ntawm ob lub pyramids uas muaj ib lub ntsej muag thiab sib cuam tshuam los ntawm peb qhov vertices. Ib qho piv txwv yog acetylene molecule.
Ua ntej, cov molecules no tsis muaj cis lossis trans isomers. Qhov thib ob, carbon atoms tsis tuaj yeem tig ib ncig ntawm lawv cov axis. Thiab qhov thib peb, tag nrho cov atoms thiab lawv cov radicals nyob ntawm tib lub axis, thiab lub kaum sab xis yog 180 degrees.
Tau kawg, cov xwm txheej tau piav qhia tuaj yeem siv rau cov khoom uas nws lub cev pob txha muaj ntau dua ob lub atoms hydrogen. Lub hauv paus ntsiab lus ntawm stereometric kev tsim kho ntawm xws li molecules yog khaws cia.
Spatial qauv ntawm molecules ntawm inorganic tshuaj
Qhov tsim ntawm covalent daim ntawv cog lus nyob rau hauv inorganic tebchaw yog zoo ib yam nyob rau hauv mechanism rau cov organic tshuaj. Yuav kom tsim tau ib daim ntawv cog lus, nws yog ib qho tsim nyog yuav tsum muaj cov khoom siv hluav taws xob tsis sib koom hauv ob lub atoms, uas tsim cov huab cua sib xws.
Kev sib tshooj ntawm orbitals thaum lub sij hawm tsim ntawm covalent daim ntawv cog lus tshwm sim raws ib kab ntawm atomic nuclei. Yog tias ib qho atom tsim ob lossis ntau daim ntawv cog lus, ces qhov kev ncua deb ntawm lawv yog tus cwj pwm los ntawm tus nqi ntawm lub kaum sab xis.
Yog tias peb xav txog cov dej molecule, uas yog tsim los ntawm ib qho oxygen atom thiab ob lub hydrogen atoms, lub kaum sab xis yuav tsum yog 90 degrees. Txawm li cas losCov kev tshawb fawb sim tau pom tias tus nqi no yog 104.5 degrees. Cov qauv spatial ntawm molecules txawv ntawm qhov theoretically kwv yees ib qho vim muaj kev cuam tshuam ntawm cov rog ntawm hydrogen atoms. Lawv ntxeev siab rau ib leeg, yog li ua kom txoj hlua khi ntawm lawv.
Sp-hybridization
Hybridization yog txoj kev xav ntawm kev tsim cov hybrid tib yam orbitals ntawm ib lub molecule. Qhov tshwm sim no tshwm sim vim muaj qhov tsis sib koom ua ke ntawm cov hluav taws xob sib txawv ntawm qib zog sib txawv hauv nruab nrab atom.
Piv txwv li, xav txog kev tsim cov nyiaj sib cog lus hauv BeCl2 molecule. Beryllium muaj unshared electron khub ntawm qib s thiab p, uas nyob rau hauv txoj kev xav yuav tsum ua rau cov tsim ntawm ib tug uneven kaum molecule. Txawm li cas los xij, hauv kev xyaum lawv yog linear thiab lub kaum sab xis yog 180 degrees.
Sp-hybridization yog siv los tsim ob daim ntawv cog lus. Txawm li cas los xij, muaj lwm hom kev tsim ntawm hybrid orbitals.
Sp2 hybridization
Hom kev sib xyaw no yog lub luag haujlwm rau cov qauv spatial ntawm molecules nrog peb covalent bonds. Ib qho piv txwv yog BCl3 molecule. Lub hauv paus barium atom muaj peb qhov tsis sib koom ua ke electron: ob ntawm p-theem thiab ib qho ntawm s-theem.
Peb daim ntawv cog lus tsim cov molecule uas nyob hauv tib lub dav hlau, thiab nws lub kaum sab xis yog 120 degrees.
Sp3 hybridization
Lwm qhov kev xaiv rau kev tsim cov hybrid orbitals, thaum lub hauv paus atom muaj 4 tsis sib koom electron khub: 3 ntawm p-theem thiab 1 ntawm s-theem. Ib qho piv txwv ntawm cov khoom no yog methane. Lub spatial qauv ntawm methane molecules yog ib tug tetraerd, lub valence kaum nyob rau hauv uas yog 109.5 degrees. Qhov kev hloov ntawm lub kaum sab xis yog tus cwj pwm los ntawm kev sib cuam tshuam ntawm hydrogen atoms nrog ib leeg.
