Txhua lub cev uas nyob ib puag ncig peb yog tsim los ntawm atoms. Atoms, nyob rau hauv lem, sib sau ua ke rau hauv ib tug molecule. Nws yog vim qhov sib txawv ntawm cov qauv molecular uas ib tus tuaj yeem tham txog cov khoom sib txawv ntawm ib leeg, raws li lawv cov khoom thiab cov tsis muaj. Molecules thiab atoms yeej ib txwm nyob rau hauv lub xeev ntawm dynamics. Tsiv mus, lawv tseem tsis tawg nyob rau hauv ntau cov lus qhia, tab sis nyob rau hauv ib tug tej yam qauv, uas peb tshuav rau lub hav zoov ntawm xws li ib tug lossis loj ntau yam ntawm cov khoom nyob rau hauv tag nrho lub ntiaj teb no nyob ib ncig ntawm peb. Cov khoom no yog dab tsi thiab lawv cov khoom yog dab tsi?
Cov ntsiab lus dav dav
Yog peb pib los ntawm txoj kev xav ntawm quantum mechanics, ces cov molecule tsis muaj cov atoms, tab sis lawv cov nuclei thiab electrons, uas niaj hnub cuam tshuam nrog ib leeg.
Rau qee yam tshuaj, molecule yog qhov me tshaj plaws uas muaj cov khoom xyaw thiab tshuaj lom neeg ntawm cov tshuaj nws tus kheej. Yog li, cov khoom ntawm molecules los ntawm qhov pom ntawm chemistry yog txiav txim siab los ntawm nws cov qauv tshuaj thiabmuaj pes tsawg leeg. Tab sis tsuas yog rau cov khoom uas muaj cov qauv molecular, txoj cai ua haujlwm: cov khoom siv tshuaj lom neeg ntawm cov khoom thiab cov molecules yog tib yam. Rau qee cov polymers, xws li ethylene thiab polyethylene, muaj pes tsawg leeg tsis phim cov molecular muaj pes tsawg leeg.
Nws paub tias cov khoom ntawm molecules tau txiav txim siab tsis yog los ntawm tus lej ntawm atoms, lawv hom, tab sis kuj los ntawm kev teeb tsa, qhov kev txiav txim ntawm kev sib txuas. Ib tug molecule yog ib tug complex architectural qauv, qhov twg txhua yam nyob rau hauv nws qhov chaw thiab muaj nws cov neeg nyob ze. Cov qauv atomic tuaj yeem nruj dua lossis tsawg dua. Txhua atom vibrates txog nws txoj hauj lwm sib npaug.
Kev teeb tsa thiab tsis muaj
Nws tshwm sim tias qee qhov ntawm cov molecule tig nyob rau hauv kev sib raug zoo rau lwm qhov chaw. Yog li, nyob rau hauv tus txheej txheem ntawm thermal motion, ib tug dawb molecule yuav siv sij hawm nyob rau hauv cov duab txawv txawv (configurations).
Yeej, cov khoom ntawm molecules yog txiav txim siab los ntawm daim ntawv cog lus (nws hom) ntawm cov atoms thiab cov qauv ntawm cov molecule nws tus kheej (cov qauv, cov duab). Yog li, ua ntej ntawm tag nrho cov, cov kev tshawb xav ntawm cov tshuaj siv tshuaj yog xam cov tshuaj bonds thiab yog raws li cov khoom ntawm atoms.
Nrog lub polarity muaj zog, cov khoom ntawm cov molecules yog qhov nyuaj los piav qhia nrog ob lossis peb qhov kev sib raug zoo, uas zoo heev rau cov tsis muaj polar molecules. Yog li ntawd, ib qho ntxiv parameter nrog lub sijhawm dipole tau qhia. Tab sis txoj kev no tsis yog ib txwm ua tiav, txij li cov polar molecules muaj cov yam ntxwv ntawm tus kheej. Parameters kuj tau thov kom suav rau quantum teebmeem, uas yog qhov tseem ceeb ntawm qhov kub thiab txias.
Peb paub dab tsi txog cov molecule ntawm cov khoom siv ntau tshaj plaws hauv ntiaj teb?
Ntawm txhua yam khoom hauv peb lub ntiaj teb, feem ntau yog dej. Nws, nyob rau hauv qhov tseeb, muab lub neej rau txhua yam uas muaj nyob rau hauv lub ntiaj teb no. Tsuas yog cov kab mob tuaj yeem ua yam tsis muaj nws, qhov seem ntawm cov txheej txheem nyob hauv lawv cov muaj pes tsawg leeg rau feem ntau muaj dej. Dab tsi ntawm cov dej molecule, yam ntxwv ntawm nws, yog siv nyob rau hauv lub economic lub neej ntawm tib neeg thiab cov tsiaj qus ntawm lub ntiaj teb?
Tom qab tag nrho, qhov no yog cov khoom tshwj xeeb tiag tiag! Tsis muaj lwm yam khoom muaj peev xwm khav tau ntawm cov khoom muaj nyob hauv dej.
Dej yog qhov hnyav hauv qhov xwm txheej. Tag nrho cov kev tshwm sim tshwm sim nyob rau hauv cov kab mob nyob, ib txoj kev los yog lwm yam, tshwm sim nyob rau hauv cov dej ib puag ncig. Ntawd yog, cov tshuaj nkag mus rau hauv cov tshuaj tiv thaiv thaum nyob hauv lub xeev yaj.
Dej muaj peev xwm ua kom sov zoo, tab sis qis thermal conductivity. Ua tsaug rau cov khoom no, peb tuaj yeem siv nws ua kev thauj mus los. Lub hauv paus ntsiab lus no suav nrog hauv kev ua kom txias ntawm ntau cov kab mob. Hauv kev lag luam hluav taws xob nuclear, cov khoom ntawm cov dej molecule tau nce mus rau kev siv cov khoom no ua ib qho coolant. Ntxiv nrog rau qhov muaj peev xwm ua qhov nruab nrab rau lwm yam tshuaj, dej nws tus kheej tuaj yeem nkag mus rau hauv cov tshuaj tiv thaiv: photolysis, hydration, thiab lwm yam.
Natural pure water is anodorless, colorless and tasteless kua. Tab sis ntawm txheej thickness ntau dua 2 meters, cov xim yuav xiav.
Tag nrho cov dej molecule yog dipole (ob tug opposite ncej). Nws yog tus qauv dipole hauvFeem ntau txiav txim siab qhov txawv txav ntawm cov khoom no. Cov dej molecule yog ib daim diam.
Hlau dej muaj lwm yam khoom muaj txiaj ntsig: nws cov molecule tau txais cov qauv ntawm cov qauv kub, thiab cov qauv ntawm cov khoom tau txais cov proportions ntawm cov seem golden. Ntau yam ntawm cov khoom ntawm cov dej molecule tau tsim los ntawm kev tshuaj xyuas qhov nqus thiab emission ntawm striped spectra nyob rau hauv cov roj theem.
Kev tshawb fawb thiab molecular zog
Txhua yam tshuaj, tshwj tsis yog tshuaj lom neeg, muaj lub cev lub cev ntawm cov molecules uas ua rau lawv cov qauv.
Hauv kev tshawb fawb lub cev, lub tswv yim ntawm cov molecules yog siv los piav qhia cov khoom ntawm cov khoom khib nyiab, kua thiab roj. Lub peev xwm ntawm tag nrho cov tshuaj diffuse, lawv viscosity, thermal conductivity thiab lwm yam khoom yog txiav txim los ntawm kev txav ntawm cov molecules. Thaum tus kws kho mob Fab Kis Fab Kis Jean Perrin tab tom kawm txog Brownian cov lus tsa suab, nws tau sim ua pov thawj tias muaj cov molecules. Txhua yam muaj sia nyob muaj nyob vim muaj kev sib raug zoo nrog kev sib raug zoo hauv cov qauv. Tag nrho cov khoom siv tshuaj thiab lub cev ntawm cov khoom yog qhov tseem ceeb rau kev tshawb fawb ntuj. Kev loj hlob ntawm physics, chemistry, biology thiab molecular physics tau nce mus rau xws li kev tshawb fawb xws li molecular biology, uas kawm txog cov xwm txheej hauv lub neej.
Siv cov ntsuas ntsuas ntsuas ntsuas, lub cev lub cev ntawm cov molecules, uas txiav txim siab los ntawm molecular spectroscopy, hauv chemistry lub cev txiav txim siab qhov ntsuas kub ntawm cov khoom tsim nyog los xam cov tshuaj sib npaug thiab cov nqi ntawm nws qhov chaw tsim khoom.
Qhov txawv ntawm cov khoom ntawm atoms thiab molecules yog dab tsi?
Ua ntej tshaj plaws, atoms tsis tshwm sim hauv lub xeev dawb.
Molecules muaj ntau dua qhov muag pom. Qhov no yog vim qhov qis symmetry ntawm lub kaw lus thiab qhov tshwm sim ntawm qhov muaj peev xwm ntawm kev hloov pauv tshiab thiab oscillations ntawm cov nuclei. Rau ib lub molecule, tag nrho lub zog muaj peb lub zog uas sib txawv raws li qhov loj ntawm cov khoom:
- lub plhaub hluav taws xob (optical lossis ultraviolet hluav taws xob);
- vibrations ntawm nuclei (infrared ib feem ntawm lub spectrum);
- kev sib hloov ntawm cov molecule tag nrho (xov tooj cua zaus ntau).
Atoms emit tus yam ntxwv kab spectra, thaum molecules emit striped spectra muaj ntau kab nyob ze.
Spectral tsom xam
Kho qhov muag, hluav taws xob, sib nqus thiab lwm yam khoom ntawm lub molecule kuj tau txiav txim siab los ntawm kev sib txuas nrog cov haujlwm nthwv dej. Cov ntaub ntawv ntawm cov xeev ntawm cov molecules thiab qhov yuav hloov pauv ntawm lawv qhia txog molecular spectra.
Kev hloov pauv (electronic) hauv cov molecules qhia cov tshuaj sib txuas thiab cov qauv ntawm lawv cov plhaub hluav taws xob. Spectra nrog ntau qhov sib txuas muaj qhov ntev-wavelength absorption bands uas poob rau hauv cheeb tsam pom. Yog hais tias ib yam khoom yog tsim los ntawm xws li molecules, nws muaj ib tug yam ntxwv xim. Cov no yog cov organic dyes.
Cov khoom ntawm molecules ntawm tib yam khoom yog tib yam hauv txhua lub xeev ntawm kev sib sau. Qhov no txhais tau hais tias nyob rau hauv tib yam khoom, cov khoom ntawm cov molecules ntawm cov kua, gaseous tshuaj tsis txawv ntawm cov khoom ntawm cov khoom. Lub molecule ntawm ib yam khoom ib txwm muaj tib lub qauv, tsis hais txogaggregate state of matter nws tus kheej.
Electrical data
Txoj kev uas cov tshuaj coj mus rau hauv qhov hluav taws xob yog txiav txim siab los ntawm cov yam ntxwv hluav taws xob ntawm cov molecules: polarizability thiab mus tas li dipole lub sijhawm.
Dipole lub sijhawm yog qhov hluav taws xob asymmetry ntawm lub molecule. Cov molecules uas muaj qhov nruab nrab ntawm symmetry zoo li H2 tsis muaj lub sijhawm dipole mus tas li. Lub peev xwm ntawm lub plhaub hluav taws xob ntawm lub molecule txav tau los ntawm kev cuam tshuam ntawm lub zog hluav taws xob, vim qhov tshwm sim ntawm qhov tshwm sim ntawm lub sijhawm dipole yog tsim nyob rau hauv nws, yog polarizability. Txhawm rau nrhiav tus nqi ntawm polarizability thiab dipole lub sijhawm, nws yog ib qho tsim nyog los ntsuas qhov permittivity.
Tus cwj pwm ntawm lub teeb nthwv dej hauv qhov chaw hluav taws xob hloov pauv yog tus cwj pwm los ntawm cov khoom siv kho qhov muag ntawm cov khoom, uas tau txiav txim siab los ntawm polarizability ntawm ib qho molecule ntawm cov khoom no. Muaj feem cuam tshuam ncaj qha rau polarizability yog: tawg, refraction, kev ua haujlwm kho qhov muag thiab lwm yam tshwm sim ntawm molecular optics.
Ib tug tuaj yeem hnov lo lus nug: "Yuav ua li cas, dua li cov molecules, cov khoom ntawm cov khoom nyob ntawm seb dab tsi?" Cov lus teb yog yooj yim heev.
Cov khoom ntawm cov khoom, tshwj tsis yog rau isometry thiab cov qauv siv lead ua, yog txiav txim siab los ntawm qhov kub ntawm ib puag ncig, cov khoom nws tus kheej, siab, muaj impurities.
Tshuaj ntawm molecules
Ua ntej tsim kev tshawb fawb ntawm quantum mechanics, qhov xwm txheej ntawm cov tshuaj lom neeg hauv cov molecules yog qhov tsis paub meej. Classical physics piav qhia kev taw qhia thiabsaturation ntawm valence bonds tsis tuaj yeem. Tom qab tsim cov ntaub ntawv theoretical tseem ceeb ntawm cov tshuaj tiv thaiv kab mob (1927) siv cov piv txwv ntawm H2 molecule yooj yim tshaj plaws, txoj kev xav thiab kev suav tau pib maj mam txhim kho. Piv txwv li, raws li kev siv dav dav ntawm cov qauv ntawm molecular orbitals, quantum chemistry, nws tau los ua kom suav cov kev sib txawv ntawm qhov sib txawv, lub zog ntawm cov molecules thiab cov tshuaj sib txuas, kev faib tawm ntawm electron ceev thiab lwm yam ntaub ntawv uas tau ua tiav nrog cov ntaub ntawv sim.
Cov khoom muaj tib yam muaj pes tsawg leeg, tab sis cov qauv tshuaj sib txawv thiab cov khoom sib txawv, hu ua cov qauv isomers. Lawv muaj cov qauv qauv sib txawv, tab sis tib cov qauv molecular.
Ntau hom qauv isomerism paub. Qhov sib txawv yog nyob rau hauv cov qauv ntawm cov pob txha pob txha, txoj hauj lwm ntawm pawg neeg ua haujlwm, los yog txoj hauj lwm ntawm ntau daim ntawv cog lus. Tsis tas li ntawd, tseem muaj spatial isomers nyob rau hauv uas cov khoom ntawm ib yam khoom molecule yog yus muaj los ntawm tib yam muaj pes tsawg leeg thiab tshuaj qauv. Yog li ntawd, cov qauv thiab cov qauv molecular yog tib yam. Qhov sib txawv yog nyob rau hauv spatial zoo ntawm lub molecule. Cov qauv tshwj xeeb yog siv los sawv cev sib txawv spatial isomers.
Muaj cov tebchaw uas hu ua homologues. Lawv zoo ib yam nyob rau hauv cov qauv thiab cov khoom, tab sis txawv nyob rau hauv muaj pes tsawg leeg los ntawm ib los yog ntau tshaj CH2 pawg. Txhua yam khoom zoo sib xws hauv cov qauv thiab cov khoom sib xyaw ua ke hauv homologous series. Tau kawm txog cov khoom ntawm ib homologue, ib tus tuaj yeem xav txog lwm yam ntawm lawv. Cov txheej txheem homologs yog homologous series.
Thaum hloov cov qauv ntawm cov teeb meemcov tshuaj lom neeg cov khoom ntawm molecules hloov dramatically. Txawm tias cov ntsiab lus yooj yim tshaj plaws ua piv txwv: methane, thaum ua ke nrog ib qho oxygen atom, dhau los ua kua tshuaj lom hu ua methanol (methyl cawv - CH3OH). Yog li ntawd, nws cov tshuaj complementarity thiab cov nyhuv ntawm cov kab mob nyob ua ke yuav txawv. Zoo sib xws tab sis ntau qhov kev hloov pauv tshwm sim thaum hloov kho cov qauv ntawm biomolecules.
Tshuaj lom neeg cov khoom muaj zog nyob ntawm cov qauv thiab cov khoom ntawm cov molecules: ntawm lub zog sib cog lus hauv nws thiab cov geometry ntawm cov molecule nws tus kheej. Qhov no yog tshwj xeeb tshaj yog muaj tseeb nyob rau hauv biologically active compounds. Qhov kev sib tw cov tshuaj tiv thaiv yuav yog qhov tseem ceeb tshaj plaws yog feem ntau txiav txim siab tsuas yog los ntawm spatial yam, uas nyob rau hauv lem nyob ntawm tus thawj molecules (lawv configuration). Ib lub molecule nrog qhov "tsis xis nyob" kev teeb tsa yuav tsis hnov mob txhua, thaum lwm qhov nrog tib cov tshuaj muaj pes tsawg leeg tab sis txawv geometry yuav hnov mob tam sim.
Ntau tus txheej txheem lom neeg tau pom thaum lub sijhawm loj hlob thiab kev tsim tawm yog txuam nrog kev sib raug zoo ntawm geometric ntawm cov khoom siv tshuaj tiv thaiv thiab cov khoom pib. Rau koj cov ntaub ntawv: qhov kev txiav txim ntawm ntau tus lej ntawm cov tshuaj tshiab yog ua raws li cov qauv molecular zoo sib xws ntawm cov khoom sib xyaw uas ua rau muaj kev phom sij los ntawm kev ua rau tib neeg lub cev. Cov tshuaj siv qhov chaw ntawm qhov teeb meem molecule thiab ua rau nws nyuaj rau ua.
Nrog kev pab los ntawm cov qauv tshuaj, qhov muaj pes tsawg leeg thiab cov khoom ntawm cov molecules ntawm cov khoom sib txawv tau qhia. Raws li qhov hnyav molecular, tshuaj ntsuam xyuas, qhov sib piv atomic yog tsim thiab muab tso ua keempirical formula.
geometry
Kev txiav txim siab ntawm cov qauv geometric ntawm lub molecule yog ua los ntawm kev txiav txim siab qhov sib npaug ntawm cov atomic nuclei. Lub zog ntawm kev sib cuam tshuam ntawm atoms nyob ntawm qhov kev ncua deb ntawm nuclei ntawm atoms. Ntawm qhov deb heev, lub zog no yog xoom. Raws li cov atoms mus rau ib leeg, ib qho tshuaj lom neeg pib tsim. Tom qab ntawd cov atoms tau sib zog ua ke.
Yog tias muaj qhov tsis txaus ntseeg, ces kev tsim cov tshuaj lom neeg tsis tsim nyog. Yog hais tias lub atoms pib mus ze ze, electrostatic repulsive rog pib ua ntawm lub nuclei. Ib qho kev cuam tshuam rau kev sib koom ua ke ntawm cov atoms yog qhov tsis sib xws ntawm lawv cov khoom siv hluav taws xob sab hauv.
Sizes
Nws tsis tuaj yeem pom cov molecules nrog qhov muag liab qab. Lawv me me heev uas txawm tias lub tshuab tsom nrog 1000x magnification yuav tsis pab peb pom lawv. Biologists saib cov kab mob me me li 0.001 hli. Tab sis cov molecules yog ntau pua thiab txhiab zaus me dua.
Hnub no, cov qauv ntawm cov qauv ntawm cov khoom siv tau txiav txim siab los ntawm txoj kev diffraction: neutron diffraction, X-ray diffraction tsom xam. Kuj tseem muaj kev vibrational spectroscopy thiab electron paramagnetic txoj kev. Qhov kev xaiv ntawm txoj kev yog nyob ntawm hom khoom thiab nws tus mob.
Qhov loj ntawm lub molecule yog tus nqi raws cai, suav nrog lub plhaub hluav taws xob. Lub ntsiab lus yog qhov deb ntawm electrons los ntawm atomic nuclei. Qhov loj dua lawv, qhov tsawg dua nws yuav pom cov electrons ntawm cov molecule. Hauv kev xyaum, qhov loj ntawm cov molecules tuaj yeem txiav txim siab los ntawm kev coj mus rau hauv tus account qhov sib npaug ntawm qhov deb. Qhov no yog lub sijhawm uas cov molecules lawv tus kheej tuaj yeem txav mus rau ib leeg thaum ntim ntom ntom hauv cov siv lead ua molecular thiab hauv cov kua.
Cov kev deb loj muaj cov molecules los nyiam, thiab cov me me, ntawm qhov tsis sib xws, rau kev tawm tsam. Yog li ntawd, X-ray diffraction tsom xam ntawm molecular crystals pab nrhiav qhov ntev ntawm lub molecule. Siv cov coefficient ntawm diffusion, thermal conductivity thiab viscosity ntawm gases, nrog rau qhov ceev ntawm ib yam khoom nyob rau hauv ib tug condensed lub xeev, ib tug yuav txiav txim seb qhov kev txiav txim ntawm magnitude ntawm molecular ntau thiab tsawg.
