Alpha thiab beta hluav taws xob feem ntau hu ua hluav taws xob decays. Qhov no yog txheej txheem uas yog emission ntawm subatomic hais los ntawm lub nucleus, tshwm sim ntawm ib tug zoo kawg li ceev. Yog li ntawd, ib qho atom lossis nws cov isotope tuaj yeem hloov ntawm ib qho tshuaj mus rau lwm qhov. Alpha thiab beta lwj ntawm nuclei yog cov yam ntxwv ntawm cov ntsiab lus tsis ruaj khov. Cov no suav nrog tag nrho cov atoms uas tus lej them ntau dua 83 thiab tus lej loj dua 209.
Reaction condition
Decomposition, zoo li lwm yam kev hloov pauv hluav taws xob, yog ntuj thiab dag. Qhov kawg tshwm sim vim qhov ingress ntawm ib co txawv teb chaws particle mus rau hauv lub nucleus. Ntau npaum li cas alpha thiab beta decay ib atom tuaj yeem nkag mus tsuas yog nyob ntawm seb lub xeev ruaj khov mus txog li cas.
Raws li tej yam ntuj tso, alpha thiab beta rho tawm decays tshwm sim.
Nyob rau hauv cov khoom tsim, neutron, positron, proton thiab lwm yam, tsis tshua muaj hom kev lwj thiab kev hloov pauv ntawm nuclei tam sim no.
Cov npe no tau muab los ntawm Ernest Rutherford, uas kawm txog hluav taws xob hluav taws xob.
Qhov txawv ntawm qhov ruaj khov thiab tsis ruaj khovcore
Lub peev xwm ua kom lwj ncaj qha nyob ntawm lub xeev ntawm lub atom. Lub thiaj li hu ua "stable" los yog non-radioactive nucleus yog cov yam ntxwv ntawm cov atoms tsis lwj. Hauv txoj kev xav, cov ntsiab lus zoo li no tuaj yeem raug soj ntsuam tas li txhawm rau kom ntseeg tau thaum kawg ntawm lawv qhov kev ruaj ntseg. Qhov no yog qhov yuav tsum tau txhawm rau txhawm rau cais cov nuclei ntawm cov tsis ruaj khov, uas muaj lub neej ntev heev.
Yuav ua yuam kev, xws li "slow" atom tuaj yeem yuam kev rau qhov ruaj khov. Txawm li cas los xij, tellurium, thiab tshwj xeeb tshaj yog, nws tus lej isotope 128, uas muaj ib nrab-lub neej ntawm 2.2·1024 xyoo, tuaj yeem ua piv txwv zoo. Cov ntaub ntawv no tsis cais. Lanthanum-138 muaj ib nrab neej ntawm 1011 xyoo. Lub sijhawm no yog peb caug npaug ntawm lub hnub nyoog ntawm lub ntiaj teb uas twb muaj lawm.
Lub ntsiab lus ntawm cov hluav taws xob tawg
txheej txheem no tshwm sim random. Txhua qhov decaying radionuclide tau txais tus nqi uas tas li rau txhua kis. Tus nqi lwj tsis tuaj yeem hloov pauv raws li kev cuam tshuam ntawm lwm yam. Nws tsis muaj teeb meem yog tias cov tshuaj tiv thaiv yuav tshwm sim nyob rau hauv lub zog ntawm lub zog gravitational loj, ntawm xoom xoom, hauv hluav taws xob thiab hlau nplaum, thaum muaj tshuaj tiv thaiv, thiab lwm yam. Cov txheej txheem tuaj yeem cuam tshuam tsuas yog los ntawm kev cuam tshuam ncaj qha rau sab hauv ntawm lub atomic nucleus, uas yog xyaum ua tsis tau. Cov tshuaj tiv thaiv yog tus kheej thiab nyob ntawm lub atom uas nws tau mus thiab nws lub xeev sab hauv.
Thaum xa mus rau cov hluav taws xob tawg, lo lus "radionuclide" feem ntau siv. Rau cov uas tsis yogpaub txog nws, koj yuav tsum paub tias lo lus no qhia txog ib pawg ntawm cov atoms uas muaj cov khoom siv hluav taws xob, lawv tus lej loj, tus lej atomic thiab lub zog.
Ntau yam radionuclides yog siv rau hauv kev, kev tshawb fawb thiab lwm qhov chaw ntawm tib neeg lub neej. Piv txwv li, hauv cov tshuaj, cov ntsiab lus no yog siv rau kev kuaj mob, ua cov tshuaj, cov cuab yeej thiab lwm yam khoom. Tseem muaj ntau tus kws kho mob thiab cov xov tooj cua prognostic.
Tsis muaj qhov tseem ceeb yog qhov txhais ntawm isotope. Lo lus no hais txog ib yam tshwj xeeb ntawm atoms. Lawv muaj tus lej atomic tib yam li cov khoom qub, tab sis cov lej sib txawv. Qhov sib txawv no yog tshwm sim los ntawm tus naj npawb ntawm neutrons, uas tsis cuam tshuam rau tus nqi, xws li protons thiab electrons, tab sis hloov lawv cov huab hwm coj. Piv txwv li, yooj yim hydrogen muaj ntau npaum li 3 ntawm lawv, qhov no yog tib lub caij uas nws cov isotopes tau muab lub npe: deuterium, tritium (tsuas yog radioactive ib qho) thiab protium. Hauv lwm qhov xwm txheej, cov npe tau muab raws li cov atomic masses thiab lub ntsiab tseem ceeb.
Alpha lwj
Nov yog hom tshuaj tiv thaiv kab mob. Nws yog ib qho tseem ceeb rau tej yam ntuj tso los ntawm lub thib rau thiab xya lub sij hawm ntawm lub sij hawm lub sij hawm ntawm cov tshuaj. Tshwj xeeb tshaj yog rau cov khoom siv dag zog lossis cov khoom siv transuranium.
Cov ntsiab lus raug rau alpha lwj
Tus naj npawb ntawm cov hlau uas yog cov yam ntxwv ntawm qhov kev lwj no suav nrog thorium, uranium thiab lwm cov ntsiab lus ntawm lub sijhawm thib rau thiab xya ntawm lub sijhawm ntawm cov khoom siv tshuaj, suav los ntawm bismuth. Cov txheej txheem kuj undergoes isotopes los ntawm cov hnyavkhoom.
Yuav ua li cas thaum muaj kev tawm tsam?
Thaum alpha lwj pib, cov pa tawm los ntawm cov nucleus ntawm cov khoom uas muaj 2 protons thiab ib khub ntawm neutrons. Lub emission particle nws tus kheej yog lub nucleus ntawm ib tug helium atom, nrog ib tug loj ntawm 4 units thiab tus nqi ntawm +2.
Vim li ntawd, lub caij tshiab tshwm sim, uas nyob ob lub hlwb mus rau sab laug ntawm tus thawj hauv lub sijhawm. Qhov kev npaj no yog txiav txim siab los ntawm qhov tseeb tias thawj atom tau poob 2 protons thiab nrog rau nws - tus nqi pib. Raws li qhov tshwm sim, qhov loj ntawm qhov tshwm sim isotope raug txo los ntawm 4 pawg loj piv rau lub xeev pib.
Examples
Thaum lub sijhawm lwj no, thorium yog tsim los ntawm uranium. Los ntawm thorium tuaj radium, los ntawm nws los ntawm radon, uas nws thiaj li muab polonium, thiab thaum kawg txhuas. Hauv cov txheej txheem no, isotopes ntawm cov ntsiab lus tau tsim, thiab tsis yog lawv tus kheej. Yog li, nws hloov tawm uranium-238, thorium-234, radium-230, radon-236 thiab lwm yam, mus txog qhov pom ntawm cov khoom ruaj khov. Cov mis rau cov tshuaj tiv thaiv no yog raws li nram no:
Th-234 -> Ra-230 -> Rn-226 -> Po-222 -> Pb-218
Qhov ceev ntawm cov alpha particle uas tau xaiv thaum lub sijhawm emission yog los ntawm 12 txog 20 txhiab km / sec. Nyob rau hauv lub tshuab nqus tsev, xws li ib tug particle yuav voj voog lub ntiaj teb nyob rau hauv 2 vib nas this, tsiv raws tus kab zauv.
Beta Decay
Qhov txawv ntawm qhov khoom no thiab ib qho hluav taws xob nyob rau hauv qhov chaw ntawm qhov tsos. Beta decay tshwm sim nyob rau hauv lub nucleus ntawm ib tug atom, tsis nyob rau hauv lub electron plhaub nyob ib ncig ntawm nws. Feem ntau ntawm tag nrho cov kev hloov pauv hluav taws xob uas twb muaj lawm. Nws tuaj yeem pom nyob rau hauv yuav luag txhua qhov tam sim notshuaj lom neeg. Nws ua raws los ntawm qhov no tias txhua lub ntsiab lus muaj tsawg kawg yog ib qho isotope raug lwj. Feem ntau, beta decay ua rau beta-minus decay.
Reaction flow
Nyob rau hauv cov txheej txheem no, ib qho hluav taws xob tawm ntawm lub nucleus, uas tau tshwm sim vim qhov hloov pauv ntawm cov neutron mus rau hauv electron thiab proton. Hauv qhov no, vim qhov loj dua, cov protons tseem nyob hauv lub nucleus, thiab cov electron, hu ua beta minus particle, tawm ntawm lub atom. Thiab txij li thaum muaj ntau protons nyob rau hauv ib chav tsev, lub nucleus ntawm lub caij nws tus kheej hloov upwards thiab nyob rau sab xis ntawm tus thawj nyob rau hauv lub periodic rooj.
Examples
Kev lwj ntawm beta nrog potassium-40 hloov nws mus rau hauv calcium isotope, uas nyob rau sab xis. Radioactive calcium-47 dhau los ua scandium-47, uas tuaj yeem hloov mus rau hauv titanium-47 ruaj khov. Qhov no beta lwj zoo li cas? Formula:
Ca-47 -> Sc-47 -> Ti-47
Qhov ceev ntawm beta particle yog 0.9 npaug ntawm qhov ceev ntawm lub teeb, uas yog 270,000 km / sec.
Tsis muaj ntau ntau beta-active nuclides nyob rau hauv cov xwm. Muaj tsawg heev qhov tseem ceeb. Ib qho piv txwv yog poov tshuaj-40, uas tsuas yog 119/10,000 nyob rau hauv ib tug natural sib tov. Tsis tas li ntawd, ntawm qhov tseem ceeb ntawm beta-minus active radionuclides yog alpha thiab beta decay khoom ntawm uranium thiab thorium.
Beta decay muaj ib qho piv txwv: thorium-234, uas nyob rau hauv alpha decay hloov mus rau hauv protactinium-234, thiab ces nyob rau hauv tib txoj kev ua uranium, tab sis nws lwm isotope tooj 234. Qhov no uranium-234 dua vim alpha. lwj uathorium, tab sis twb muaj ntau yam sib txawv ntawm nws. Qhov no thorium-230 ces dhau los ua radium-226, uas hloov mus ua radon. Thiab nyob rau hauv tib theem, mus txog thallium, tsuas yog nrog sib txawv beta hloov rov qab. Qhov no radioactive beta decay xaus nrog kev tsim cov hlau lead-206 ruaj khov. Qhov kev hloov pauv no muaj cov qauv hauv qab no:
Th-234 -> Pa-234 -> U-234 -> Th-230 -> Ra-226 -> Rn-222 -> At-218 -64432345 -218 -64432345 Pb-206
Natural thiab tseem ceeb beta nquag radionuclides yog K-40 thiab cov ntsiab lus ntawm thallium mus rau uranium.
Beta-plus decay
Tseem muaj kev hloov pauv beta ntxiv. Nws tseem hu ua positron beta decay. Nws emits ib tug particle hu ua positron los ntawm lub nucleus. Qhov tshwm sim yog qhov hloov pauv ntawm cov khoom qub rau hauv ib qho ntawm sab laug, uas muaj tus lej qis dua.
Example
Thaum electron beta lwj tshwm sim, magnesium-23 dhau los ua cov isotope ruaj khov ntawm sodium. Radioactive europium-150 ua samarium-150.
Cov tshuaj tiv thaiv beta lwj tuaj yeem tsim beta+ thiab beta-emissions. Lub particle khiav ceev nyob rau hauv ob qho tib si yog 0.9 npaug ntawm qhov ceev ntawm lub teeb.
Lwm cov xov tooj cua decays
Ntxiv rau cov kev cuam tshuam xws li alpha lwj thiab beta lwj, cov qauv uas tau paub dav, muaj lwm cov txheej txheem uas tsis tshua muaj thiab ntau tus yam ntxwv ntawm cov khoom siv radionuclides.
Neutron lwj. Ib qho nruab nrab ntawm 1 units yog emittedpawg. Thaum lub sijhawm nws, ib qho isotope hloov mus rau lwm qhov nrog cov lej me me. Ib qho piv txwv yuav yog kev hloov pauv ntawm lithium-9 rau lithium-8, helium-5 rau helium-4.
Thaum lub isotope ruaj khov ntawm iodine-127 yog irradiated nrog gamma rays, nws dhau los ua isotope tooj 126 thiab tau txais xov tooj cua.
YProton lwj. Nws yog qhov tsawg kawg nkaus. Thaum lub sij hawm nws, ib tug proton yog emission, muaj ib tug nqi ntawm +1 thiab 1 unit ntawm loj. Qhov hnyav atomic txo los ntawm ib tus nqi.
Txhua yam kev hloov pauv hluav taws xob, tshwj xeeb, cov hluav taws xob tawg, yog nrog los ntawm kev tso tawm lub zog hauv daim ntawv ntawm gamma hluav taws xob. Lawv hu nws gamma rays. Hauv qee kis, pom lub zog x-ray qis dua.
Gamma lwj. Nws yog kwj ntawm gamma quanta. Nws yog hluav taws xob electromagnetic, nyuaj tshaj X-ray, uas yog siv rau hauv cov tshuaj. Yog li ntawd, gamma quanta tshwm sim, los yog lub zog ntws los ntawm atomic nucleus. X-rays kuj yog electromagnetic tab sis pib los ntawm lub plhaub hluav taws xob ntawm lub atom.
Alpha particles khiav
Alpha hais nrog ib pawg ntawm 4 atomic units thiab tus nqi ntawm +2 txav mus rau hauv txoj kab ncaj nraim. Vim li no, peb tuaj yeem tham txog ntau yam ntawm alpha hais.
Tus nqi ntawm kev khiav yog nyob ntawm qhov pib lub zog thiab thaj tsam ntawm 3 txog 7 (qee zaum 13) cm hauv huab cua. Nyob rau hauv ib tug ntom nruab nrab, nws yog ib puas ntawm ib millimeter. Cov hluav taws xob zoo li no tsis tuaj yeem nkag mus rau ib daim ntawvdaim ntawv thiab tib neeg daim tawv nqaij.
Vim nws tus kheej huab hwm coj thiab tus lej them, alpha particle muaj lub zog ionizing siab tshaj plaws thiab rhuav tshem txhua yam hauv nws txoj kev. Hauv qhov no, alpha radionuclides yog qhov txaus ntshai tshaj plaws rau tib neeg thiab tsiaj txhu thaum raug lub cev.
Beta particle nkag mus
Vim yog tus lej me me, uas yog 1836 lub sijhawm tsawg dua li cov proton, tus nqi tsis zoo thiab qhov loj me, beta hluav taws xob muaj qhov tsis muaj zog ntawm cov khoom uas nws ya mus, tab sis ntxiv mus, lub davhlau ntev dua. Tsis tas li ntawd txoj kev ntawm cov particle tsis ncaj. Hauv qhov no, lawv hais txog kev muaj peev xwm nkag mus, uas nyob ntawm lub zog tau txais.
Lub zog nkag mus ntawm beta cov khoom tsim tawm thaum lub sij hawm siv hluav taws xob tawg mus txog 2.3 m hauv huab cua, hauv cov kua nws suav hauv centimeters, thiab hauv cov khib nyiab - hauv feem ntawm ib centimeter. Cov ntaub so ntswg ntawm tib neeg lub cev kis hluav taws xob 1.2 cm tob. Txhawm rau tiv thaiv beta hluav taws xob, cov txheej txheem yooj yim ntawm cov dej mus txog 10 cm tuaj yeem ua haujlwm. Cov dej ntws ntawm cov khoom siv nrog lub zog loj txaus ntawm 10 MeV yog yuav luag tag nrho los ntawm cov khaubncaws sab nraud povtseg: huab cua - 4 m; aluminium - 2.2 cm; hlau - 7.55 mm; lead - 5,2 mm.
Muab lawv qhov me me, cov kab hluav taws xob beta muaj qhov muaj peev xwm ionizing tsawg piv rau alpha hais. Txawm li cas los xij, thaum noj, lawv muaj kev phom sij ntau dua li thaum raug sab nraud.
Neutron thiab gamma tam sim no muaj qhov ua tau zoo tshaj plaws ntawm txhua hom hluav taws xob. Qhov ntau ntawm cov hluav taws xob hauv huab cua qee zaum nce mus txog kaum thiab ntau puameters, tab sis nrog qis ionizing kev ua tau zoo.
Feem ntau cov isotopes ntawm gamma rays tsis pub tshaj 1.3 MeV hauv lub zog. Tsis tshua muaj, qhov tseem ceeb ntawm 6.7 MeV tau mus txog. Hauv qhov no, txhawm rau tiv thaiv cov hluav taws xob zoo li no, cov txheej txheem ntawm cov hlau, pob zeb thiab cov hlau lead yog siv rau qhov attenuation factor.
piv txwv li, nyob rau hauv thiaj li yuav ua rau muaj kev cuam tshuam rau kev txiav caj npab, kev tiv thaiv txhuas, rau 100 thiab 55 cm, thiab dej - 70 thiab 115 cm.
Kev ua haujlwm ionizing ntawm neutrons nyob ntawm lawv lub zog ua haujlwm.
Txawm li cas los xij, txoj hauv kev zoo tshaj plaws los tiv thaiv hluav taws xob yog nyob deb ntawm qhov chaw raws li qhov ua tau thiab siv sijhawm tsawg li sai tau hauv thaj chaw muaj hluav taws xob siab.
Fission ntawm atomic nuclei
Nyob rau hauv lub fission ntawm lub nuclei ntawm atoms txhais tau hais tias spontaneous, los yog nyob rau hauv lub cuam tshuam ntawm neutrons, kev faib ntawm lub nucleus rau hauv ob qhov chaw, kwv yees li sib npaug zos loj.
Ob ntu no dhau los ua cov isotopes ntawm cov khoom siv hluav taws xob los ntawm lub ntsiab lus ntawm cov khoom siv tshuaj. Pib los ntawm tooj liab mus rau lanthanides.
Thaum lub sijhawm tso tawm, ob peb ntxiv neutrons khiav tawm thiab muaj ntau lub zog hauv daim ntawv ntawm gamma quanta, uas yog ntau dua thaum lub sij hawm siv hluav taws xob tawg. Yog li, nyob rau hauv ib qho kev tshwm sim ntawm radioactive decay, ib gamma quanta tshwm, thiab thaum lub sij hawm ua fission, 8, 10 gamma quanta tshwm. Tsis tas li ntawd, cov tawg tawg tawg muaj lub zog kinetic loj, uas hloov mus rau qhov ntsuas thermal.
Cov neutrons tso tawm muaj peev xwm ua rau muaj kev sib cais ntawm ib khub ntawm nuclei zoo sib xws yog tias lawv nyob ze thiab cov neutrons tsoo lawv.
Qhov no ua rau muaj peev xwm ntawm kev tawg, ua kom cov kab mob nrawm nrawm ntawm kev tawg atomic nuclei thiab tsim kom muaj zog ntau.
Thaum cov tshuaj tiv thaiv zoo li no tau tswj hwm, nws tuaj yeem siv rau qee lub hom phiaj. Piv txwv li, rau cua sov lossis hluav taws xob. Cov txheej txheem zoo li no tau ua tiav ntawm cov chaw tsim hluav taws xob nuclear thiab reactors.
Yog tias koj poob kev tswj hwm ntawm cov tshuaj tiv thaiv, kev tawg atomic yuav tshwm sim. Zoo sib xws yog siv hauv riam phom nuclear.
Nyob rau hauv tej yam ntuj tso, tsuas muaj ib lub caij - uranium, uas tsuas muaj ib tug fissile isotope nrog tus naj npawb 235. Nws yog riam phom-qib.
Nyob rau hauv ib qho yooj yim uranium atomic reactor los ntawm uranium-238, nyob rau hauv lub zog ntawm neutrons, lawv tsim ib tug tshiab isotope ntawm tus xov tooj 239, thiab los ntawm nws - plutonium, uas yog dag thiab tsis tshwm sim lawm. Hauv qhov no, qhov tshwm sim plutonium-239 yog siv rau kev siv riam phom. Cov txheej txheem ntawm fission ntawm atomic nuclei yog lub ntsiab ntawm tag nrho cov atomic riam phom thiab lub zog.
Phenomena xws li alpha lwj thiab beta lwj, cov qauv uas tau kawm hauv tsev kawm ntawv, tau nthuav dav hauv peb lub sijhawm. Ua tsaug rau cov kev cuam tshuam no, muaj cov chaw tsim hluav taws xob nuclear thiab ntau lwm yam kev lag luam raws li kev siv hluav taws xob nuclear. Txawm li cas los xij, tsis txhob hnov qab txog cov xov tooj cua ntawm ntau yam ntawm cov ntsiab lus no. Thaum ua haujlwm nrog lawv, yuav tsum muaj kev tiv thaiv tshwj xeeb thiab ua raws li txhua yam kev ceev faj. Txwv tsis pub, qhov no yuav ua raukev puas tsuaj irreparable.
