Khib nyiab: zog, qauv, ceev thiab cov piv txwv

Khoom hu xws tshuaj uas muaj peev xwm sawv ntawm txoj kev ua rau lub cev thiab muaj ib tug ntim. Ntawm dej thiab nkev, lawv yog distinguished los ntawm lawv lub cev. Cov khib nyiab khaws qhov zoo ntawm lub cev vim lub fact tias lawv hais yog tsis muaj peev xwm yuav tawm mus dawb do. Lawv txawv nyob rau hauv lawv cov kev ceev, ductility, hluav taws xob conductivity thiab xim. Lawv kuj muaj lwm yam khoom. Piv txwv li, feem ntau ntawm cov tshuaj yog melted thaum lub sij hawm cov cua kub, kis tau cov kua sau ua ib pawg xeev. Ib txhia ntawm lawv thaum rhuab tam sim ntawd gasified (sublimed). Tab sis tseem muaj cov neeg uas ua txhaum down mus rau hauv lwm yam.

Hom ntawm cov khib nyiab

Tag nrho cov khib nyiab raug muab faib ua ob pawg.

1. Amorphous, nyob rau hauv uas tus neeg hais cov txheej txheem across. Nyob rau hauv lwm yam lus, lawv tsis muaj ib tug ntshiab (tej) teeb tsa. Cov khib nyiab yuav melted nyob rau hauv ib tug tej yam kws kub luv. Feem ntau ntawm cov muaj xws li lub khob thiab cob.
2. Crystal, uas nyob rau hauv lem yog subdivided rau hauv 4 hom: atomic, molecular, ionic, nws yog xim hlau. Cov hais nyob xwb nyob rau hauv ib lub qauv, namely nyob rau hauv lub siv lead ua ntxaij ntoo. Nws geometry nyob rau hauv sib txawv tshuaj yuav txawv heev.

Crystalline khib nyiab yeej tshaj amorphous nyob rau hauv lawv cov xov tooj.

Hom ntawm crystalline khib nyiab

Nyob rau hauv suab tag nrho cov khoom tshuaj muaj ib tug crystalline qauv. Lawv txawv nyob rau hauv lawv cov qauv. Nyob rau hauv nws crystalline lattice ntshav muaj ntau yam hais thiab tshuaj. Nws yog nyob rau hauv raws li nrog lawv, thiab lawv tau txais lawv cov npe. Txhua yam muaj ib thaj chaw rau nws:

• Lub atomic siv lead ua ntxaij ntoo khoom hais txuas los ntawm ib tug covalent daim ntawv cog lus. Nws yog txawv los ntawm nws lub zog. Vim rau qhov no, xws tshuaj muaj ib tug siab melting point thiab kub. Qhov no muaj xws li hom quartz thiab pob zeb diamond.
• Nyob rau hauv lub siv lead ua ntxaij ntoo ntawm lub molecular daim ntawv cog lus ntawm tus hais yog yus muaj los ntawm nws tsis muaj zog. Tshuaj ntawm no hom yog yus muaj los yooj yim ntawm melting thiab kub. Lawv tsiag ntawv los ntawm volatility, vim uas muaj ib yam tsis hnov tsw. Cov khib nyiab yog dej khov, qab zib. Tsab ntawv tsa suab ntawm molecules nyob rau hauv cov khib nyiab ntawm no hom yog yus muaj los lawv cov kev ua.
• Lub ionic siv lead ua ntxaij ntoo nyob rau hauv cov ntshav alternate duas paub hais them zoo thiab tsis zoo. Lawv nyob rau ntawm electrostatic attraction. Qhov no lattice hom tshwm sim nyob rau hauv alkalis, ntsev, yooj yim oxides. Muaj ntau yam ntawm no hom nkag soluble nyob rau hauv cov dej. Vim ib tug heev muaj zog daim ntawv cog lus nruab nrab ntawm cov ions yog refractory. Yuav luag tag nrho cov ntawm lawv yog cov ntxhiab, txij li thaum lawv yog yus muaj los uas tsis yog-volatility. Tshuaj nrog ionic lattice tsis tau kev hluav taws xob tam sim no, raws li nyob rau hauv lawv cov muaj pes tsawg leeg tsis muaj free electrons. Ib tug raug piv txwv ntawm cov khoom ion - ntsev. Xws li ib tug siv lead ua ntxaij ntoo muab nws nkig. Qhov no yog vim lub fact tias muaj ib yam ntawm nws ua haujlwm yuav ua ion qias neeg rog.
• Lub nws yog xim hlau lead ua ntxaij ntoo tsuas tshuaj ions yog tam sim no nyob rau hauv cov ntshav, zoo them. Nruab nrab ntawm lawv muaj free electrons los ntawm kev uas kis tau zoo heev thermal thiab hluav taws xob lub zog. Uas yog vim li cas tej co sib txawv feature xws li conductivity.

General tswv yim ntawm cov khoom

Khoom tawv thiab tshuaj - nws yog suab tib yam. Cov ntsiab lus uas yog hu ua ib tug ntawm cov 4 lub xeev ntawm aggregation. Khib nyiab muaj ib tug ruaj khov daim ntawv thiab cov ua cim ntawm lub thermal tsab ntawv tsa suab ntawm atoms. Cov yav tas ua kom me me oscillations nyob ze ntawm lub equilibrium txaus. Ncau ceg ntawm science soj ntsuam txog cov kev kawm txog muaj pes tsawg leeg thiab nrog cov qauv, xa mus rau raws li tau lub xeev physics. Muaj lwm yam tseem ceeb thaj chaw ntawm kev txawj ntse muab kev koom tes nyob rau hauv xws tshuaj. Hloov tus duab los ntawm lwm influences thiab tsab ntawv tsa suab hu mechanics ntawm deformable lub cev.

Vim qhov sib txawv thaj chaw ntawm cov khib nyiab, lawv tau siv nyob rau hauv ntau yam kev pab kiag li lawm tsim los ntawm tus txiv neej. Feem ntau cov feem ntau lub hauv paus ntawm lawv cov kev siv nyob zog xws li hardness, ntim, loj, elasticity, plasticity, brittleness. Niaj hnub nimno science yuav siv tau thiab lwm yam qualities ntawm cov khib nyiab uas muaj peev xwm yuav ntes tau nkaus xwb nyob rau hauv cov kev kuaj.

Yuav ua li cas yog siv lead ua

Muaju - ib tug khoom lub cev muab tso rau hauv ib tug txiav txim hais. Txhua tshuaj nws muaj nws tus kheej qauv. Nws atoms tsim ib tug peb-dimensionally periodic stacking hu ua ntxaij ntoo. Khoom tshuaj muaj ib tug txawv qauv symmetry. Khoom crystalline lub xeev yog suav tias yog ruaj khov, vim hais tias nws muaj ib tug tsawg kawg nkaus tus nqi ntawm tej zaum zog.

Feem coob ntawm cov khoom ntaub ntawv (natural) muaj ib tug loj tus naj npawb ntawm across taw qhia kom paub ib tug neeg nplej (crystallites). Tej yam no hu ua polycrystalline. Cov no muaj xws kev alloys thiab co, raws li zoo raws li ib tug ntau ntawm cov pob zeb. Monocrystalline hu ua ntuj los yog hluavtaws ib muaju.

Nyob rau hauv feem ntau zoo li no tau lub cev yog tsim los ntawm lub xeev ntawm cov kua theem, xa mus rau yaj los yog tshuaj. Tej zaum, lawv yuav muab tau los ntawm ib tug gaseous lub xeev. Qhov no yog hu ua crystallization. Tsaug rau scientific thiab cov kev kawm tau ntawm cov sau qoob sai (synthesis) ntawm ntau yam tshuaj ua ib tug muaj scale. Feem ntau ntawm cov muaju muaj ib yam zoo ntawm ib tug tsis tu ncua polyhedron. Lawv ntau thiab tsawg pab nyias txawv nyias li. Piv txwv li, tej yam ntuj tso quartz (pob zeb siv lead ua) yuav luj li mus rau pua pua ntawm kilograms, thiab diamonds - txog li ob peb grams.

Nyob rau hauv amorphous khib nyiab, cov atoms yog nyob rau hauv qhov oscillation nyob ib ncig ntawm across nyob cov ntsiab lus. Lawv khaws ib cov luv luv-ntau kev txiav txim, tab sis tsis muaj ntev-ntau. Qhov no yog vim hais tias lawv molecules cov txheej txheem ntawm nyob rau hauv ib tug deb uas yuav muab piv nrog rau lawv cov loj. Feem ntau nyob rau hauv peb lub neej piv txwv ntawm no yog ib tug khoom glassy lub xeev. Amorphous ntaub ntawv no feem ntau kev raws li ib tug kua nrog ib tug infinitely loj viscosity. Lub sij hawm ntawm crystallization yog tej zaum thiaj li loj hais tias yog tsis qhia.

Tias tus saum toj no thaj chaw ntawm cov tshuaj ua rau lawv cim. Amorphous khib nyiab yog xam tau tias yog tsis ruaj tsis khov vim hais tias thaum lub sij hawm yuav mus rau hauv lub crystalline lub xeev.

Molecules, atoms, cov uas muaj ib tug khoom packed nrog kev kub ceev. Lawv suab kom lawv cov txheeb ze txoj hauj lwm nrog rau kev hwm rau lwm tus thiab yog nyob ua ke los ntawm intermolecular sis raug zoo. Qhov kev ncua deb ntawm lub lwg me me ntawm cov khoom nyob rau hauv txawv kev qhia no yog hu ua tus siv lead ua ntxaij ntoo parameter. Tus qauv ntawm lub tshuaj thiab nws cov symmetry txhais tau ib tug plurality cov khoom xws li electron band, cleavage thiab optics. Thaum raug rau cov khoom sufficiently loj rog, cov qualities tej zaum yuav ntau dua los yog tsawg ua txhaum. Thaum zoo li no cov khoom amenable residual deformation.

Atoms khib nyiab oscillate, uas yog vim muaj thermal zog. Txij li thaum lawv yog negligible, lawv tsuas muaj cai nyob rau hauv laboratory tej yam kev mob. Lub molecular qauv ntawm cov khib nyiab loj cuam tshuam nws lub zog.

Txoj kev tshawb no ntawm cov khib nyiab

Properties thaj chaw ntawm cov ntaub ntawv, lawv zoo thiab particle tsab ntawv tsa suab kawm ntau yam tswj ntawm khoom hauv lub xeev physics.

Rau txoj kev tshawb no siv: xov tooj cua spectroscopy, yam ntxwv tsom xam siv X-rays thiab lwm txoj kev. Yog li ntawd kawm txhua yam, lub cev thiab thermal thaj chaw ntawm cov khib nyiab. Lub hardness, kev nyuaj siab kuj, tensile zog, theem transformation kawm ntaub ntawv. Nws lom zem ntau overlaps muaj lub physics ntawm cov khib nyiab. Muaj lwm yam tseem ceeb niaj hnub science. Yuav kom kawm uas twb muaj lawm thiab synthesizing tshiab tshuaj tuav khoom hauv lub xeev Science News for KIDS.

nta khib nyiab

Ximxoo tsab ntawv tsa suab lwm electron khoom atoms txiav txim ntau ntawm nws cov khoom, piv txwv li, electrically. Muaj 5 hoob kawm xws li lub cev. Lawv teem nyob rau hauv lub hom atoms:

• Ionic, yooj yim cov yam ntxwv ntawm uas yog tus quab yuam ntawm electrostatic attraction. Nws nta: xav mus xav thiab haum ntawm lub teeb nyob rau hauv lub infrared cheeb tsam. Thaum uas tsis muaj kub, lub ionic daim ntawv cog lus yog yus muaj los ntawm cov uas tsis muaj hluav taws xob conductivity. Ib qho piv txwv ntawm xws li ib tug cov ntaub ntawv uas yog cov sodium ntsev ntawm hydrochloric acid (NaCl).
• Covalent nqa tawm nyob rau cov nuj nqis ntawm ib tug electron khub, uas belongs rau ob qho tib si atoms. Xws li ib tug txuas yog muab faib mus rau hauv: zaug xwb (ib), muab ob npaug rau thiab triple. Cov npe qhia lub xub ntiag ntawm electron officers (1, 2, 3). Ob chav thiab triple bonds yog hu ua cov zauv. Yog lwm division ntawm cov pab pawg neeg. Yog li ntawd, nyob ntawm seb lub electron ceev tis ntawm cov raug rho tawm ncov qaumteb qabteb thiab nonpolar daim ntawv cog lus. Tus thawj yog tsim los ntawm txawv atoms, thiab lub thib ob - sib npaug. Xws li ib tug khoom hauv lub xeev ntawm teeb meem, piv txwv uas yog - ib tug pob zeb diamond (C) thiab pob zeb ntais (Si), yus muaj los ntawm nws ceev. Feem ntau cov khoom muaju yog cia li ib tug covalent daim ntawv cog lus.
• Hlau tsim los ntawm combining valence electrons ntawm atoms. Raws li ib tug tshwm sim, muaj ib tug tag nrho electron huab uas yog moog nyob rau hauv tus ntawm ib tug hluav taws xob voltage. Hlau daim ntawv cog lus yog tsim thaum lub ua ke atoms ntev. Uas lawv yuav tau mus pub electrons. Muaj ntau hlau, complex tebchaw ntawm no daim ntawv cog lus yog tsim lub khoom hauv lub xeev ntawm teeb meem. Piv txwv: sodium, barium, txhuas, tooj liab, kub. Vim hais tias nonmetallic nram qab no sib txuas yuav tsum hais li no: AlCr _2, Ca ₂ Cu, Cu ₅ ZN _8. Tshuaj nrog ib tug hlau tsevneeg (co) yog muaj ntau haiv neeg nyob rau hauv lub zog. Tej zaum lawv yuav kua (Hg), mos mos (Na, K), nyuaj (W, Nb).
• Molecular sawv nyob rau hauv muaju uas tsim cais molecules ntawm qhov teeb meem. Nws yog yus muaj los ntawm khoob ntawm molecules nrog pes tsawg electron ceev. Force txuas atoms nyob rau hauv cov muaju yog txiav txim siab. Nyob rau tib lub lwg me me lawv yog attracted rau txhua lwm yam tsuas muaj zog intermolecular attraction. Uas yog vim li cas qhov cov kev mus nruab nrab ntawm lawv yog yooj yim muab los ntawm tshav kub. Cov kev sib txuas ntawm cov atoms cev qhuav dej ntau npaum li cas yooj yim. Molecular daim ntawv cog lus yog muab faib ua orientation, induction thiab dispersion. Ib qho piv txwv ntawm xws li ib tug khoom substance yog methane.
• Hydrogen, uas tshwm sim nruab nrab ntawm cov zoo polarized atoms los yog molecules thereof thiab tsis zoo polarized tsawg tshaj plaws particle ntawm ib tug qauv los yog lwm qhov chaw. Cov kev sib raug zoo muaj peev xwm yuav ntaus nqi dej khov.

Properties khib nyiab

Yuav ua li cas peb paub niaj hnub no? Zaum tau ntev tau kawm thaj chaw ntawm khoom hauv lub xeev tshuaj. Thaum raug kub thiab hloov nws. Cov kev hloov ntawm lub cev kua yog hu ua melting. Lub transformation ntawm khoom rau lub gaseous lub xeev yog hu ua sublimation. Nrog zuj zus lawm kub tshwm sim Khoom crystallization. Ib txhia tshuaj nyob rau hauv txias hloov mus rau hauv ib tug amorphous theem. Qhov no yog hu ua vitrification zaum.

Nyob rau hauv theem zaus hloov lub sab hauv qauv ntawm cov khib nyiab. Qhov siab tshaj plaws ordering nws acquires kub yog txo qis. Thaum atmospheric siab thiab ib tug kub T> 0 K tej yam khoom uas twb muaj lawm nyob rau hauv cov xwm, solidify. Tsuas yog Helium, lub crystallization uas yog tsim nyog rau lub siab ntawm 24 atm, yog ib qho kev zam rau txoj cai no.

Khoom hauv lub xeev muab nws ib tug txawv lub zog. Lawv piav qhia txog cov kev coj cwj pwm ntawm lub cev nyob rau hauv tus ntawm tej liaj teb thiab rog. Cov khoom no muab faib mus rau hauv pab pawg. 3 faib raug txoj kev sib nug xov mus rau peb hom ntawm lub zog (mechanical, thermal, electromagnetic). Raws li lawv muaj nyob rau peb pawg ntawm lub cev thaj chaw ntawm cov khib nyiab:

• Txhua yam khoom uas muaj feem rau kev nyuaj siab thiab deformation ntawm lub cev. Raws li cov txheej xwm, cov khib nyiab raug muab faib ua elastic, rheological, lub zog thiab technology. Tus so yog lub cev tseem muaj feem nws zoo lawm, tab sis nws yuav raug hloov los ntawm ib tug sab nraud quab yuam. Nyob rau hauv cov ntaub ntawv no tej zaum nws yuav ntawm yas deformation (xub pib saib tsis tau rov qab), elastic (rov qab mus rau lub yeej zoo) los yog puas (thaum ib tug tej yam pib decays / so). Saib xyuas cov kev piav qhia txog elastic moduli. Khoom tsis tsuas resists compression, ncab ib ce, tab sis tau muaj kev txav, sib ntswg thiab dabtsi yog khoov. txhav cev muaj zog rau thaum nws hu rau ntawm nws tej khoom vaj tse puas tsuaj lawm.
• Thermal manifested nyob rau hauv tus ntawm thermal teb. Ib tug ntawm cov tseem ceeb tshaj plaws zog - melting point, ntawm uas lub cev converts mus rau ib tug kua hauv lub xeev. Nws yog cai nyob rau hauv crystalline khib nyiab. Amorphous lub cev muaj latent tshav kub ntawm fusion, raws li lawv txoj kev hloov mus rau lub kua hauv lub xeev thaum lub kub yog tsa maj. Thaum ncav ib tug tej yam tshav kub amorphous lub cev loses nws elasticity thiab yuav plasticity. Lub xeev no txhais tau tias cov kev kawm tau ntawm lawv cov iav hloov kub. Thaum cua kub tshwm sim txhav lub cev deformation. Ntxiv mus, nws feem ntau nthuav. Quantitatively, tus mob no yog yus muaj los ntawm ib tug tej yam tau. Lub cev kub muaj feem xyuam rau tus neeg kho tshuab zog xws li flowability, plasticity, firmness thiab lub dag lub zog.
• Electromagnetic txuam nrog raug cov khoom microparticles tsev thiab electromagnetic vuag ntawm siab rigidity. Cov no muaj xws probation thiab radiative zog.

band qauv

Cov khib nyiab raug txwv kom muab zais thiab lub thiaj li hu ua band qauv. Yog li ntawd, nyob rau hauv lawv yog distinguished:

• Conductors, yus nyob rau hauv uas lub conductivity thiab valence bands sib tshooj. Yog li cov electrons yuav tsiv mus nyob nruab nrab ntawm lawv, yielding qhov tsawg tshaj plaws zog. Rau conductors yog tag nrho cov hlau. Thaum ib tug hluav taws xob tam sim no yog tsim rau xws li ib tug tej zaum txawv cev (vim lub dawb zog ntawm electrons ntawm cov ntsiab lus nrog tus nqi qis tshaj thiab siab tej zaum).
• Dielectrics, uas qhov chaw tsis sib tshooj. Lub caij nyoog nruab nrab lawv yog ntau tshaj 4 eV. Yuav kom cov electrons los ntawm cov valence rau yuav tsum tau loj zog conduction band. Tsaug rau cov zog dielectrics zoo uas tsis yog-conductive.
• Semiconductors, tsiag ntawv los ntawm kev qhaj ntawv ntawm cov conduction thiab valence bands. Lub caij nyoog nruab nrab lawv yog me dua 4 eV. Rau hloov lwm lub tsev ntawm electrons los ntawm cov valence mus rau lub conduction qhab yuav tsum tau tsawg zog dua dielectrics. Ntshiab (unalloyed thiab eigenfunctions) semiconductors tsis zoo tam sim no yog dhau lawm.

Molecular tsab ntawv tsa suab nyob rau hauv cov khib nyiab ua rau lawv electromagnetic zog.

lwm yam khoom

Khib nyiab raug muab faib thiab lawv sib nqus. Muaj peb pab neeg:

• Diamagnetic zog uas nyob ntawm seb me ntsis rau qhov kub thiab txias los yog rau lub xeev ntawm aggregation.
• Paramagnetic, uas ua los ntawm lub orientation ntawm lub conduction electrons thiab sib nqus sij hawm ntawm lub atoms. Raws li Curie lawv nyhav decreases li kub. Yog li, ntawm 300 K nws yog 10 ^-5.
• Ib tug sib nqus lub cev nrog ib tug txiav txim qauv muaj ntev-ntau kev txiav txim ntawm atoms. Nyob rau hauv lub pob hlav ntawm lub ntxaij ntoo yog tsis tseg cov txheej txheem hais nrog sib nqus lub sij hawm. Cov khib nyiab thiab tshuaj uas nquag siv nyob rau hauv txawv spheres ntawm tib neeg kev ua si.

Lub hardest tshuaj nyob rau hauv cov xwm

Yuav ua li cas yog lawv? khib nyiab ceev lom zem ntau seb lawv hardness. Nyob rau hauv xyoo tsis ntev los no, zaum muaj sab ob peb ntaub ntawv uas lees tias lawv ua tau "cov feem ntau check lub cev." Feem ntau cov khoom - nws fullerite (crystal molecules nrog ib tug fullerene), uas yog hais txog 1.5 lub sij hawm nyuaj tshaj pob zeb diamond. Tu siab, nws yog tam sim no muaj nyob rau hauv heev me me qhov ntau.

Rau hnub tim, lub hardest yeeb tshuaj, uas tom qab tej zaum yuav siv nyob rau hauv qhov kev lag luam - lonsdalite (hexagonal pob zeb diamond). Nws yog 58% nyuaj tshaj pob zeb diamond. Lonsdalite - allotropic kev hloov kho ntawm cov pa roj carbon. Nws siv lead ua ntxaij ntoo yog heev uas zoo sib xws rau ib tug pob zeb diamond. Lonsdaleite cell muaj 4 atoms, tab sis lub pob zeb diamond - 8. Ntawm kheev siv muaju hnub no yog lub hardest pob zeb diamond.