Lub physics ntawm cov qauv ntawm cov teeb meem yog thawj zaug kawm los ntawm Joseph J. Thomson. Txawm li cas los xij, ntau cov lus nug tseem tsis tau teb. Qee lub sij hawm tom qab, E. Rutherford muaj peev xwm tsim tau ib qho qauv ntawm cov qauv ntawm lub atom. Hauv tsab xov xwm peb yuav xav txog qhov kev paub uas coj nws mus rau qhov kev tshawb pom. Txij li cov qauv ntawm cov teeb meem yog ib qho ntawm cov ntsiab lus nthuav dav hauv cov lus qhia physics, peb yuav txheeb xyuas nws qhov tseem ceeb. Peb kawm seb lub atom muaj li cas, kawm paub nrhiav cov xov tooj ntawm electrons, protons, neutrons hauv nws. Wb paub txog lub tswvyim ntawm isotopes thiab ions.
Discovery of the electron
Nyob rau xyoo 1897, tus kws tshawb fawb Askiv Joseph John Thomson (nws daim duab tuaj yeem pom hauv qab no) tau kawm txog hluav taws xob tam sim no, uas yog, kev taw qhia ntawm cov nqi hauv cov pa roj. Lub sijhawm ntawd, physics twb paub txog cov qauv molecular ntawm cov teeb meem. Nws paub tias txhua lub cev yog tsim los ntawm cov teeb meem, uas yog ua los ntawm cov molecules, thiab tom kawg yog ua los ntawm atoms.
Thomson nrhiav pom tias, nyob rau hauv qee qhov xwm txheej, cov roj atoms tawm cov khoom nrog cov nqi tsis zoo (qel<0). Lawv hu ua electrons. Lub atom yog nruab nrab, uas txhais tau hais tias yog hais tias electrons ya tawm ntawm nws, ces zoo hais yuav tsum muaj nyob rau hauv. Dab tsi yog ib feem ntawm lub atom nrog lub cim "+"? Nws cuam tshuam li cas nrog cov hluav taws xob tsis zoo? Dab tsi txiav txim siab qhov loj ntawm ib qho atom? Lwm tus kws tshawb fawb tuaj yeem teb tag nrho cov lus nug no.
Rutherford txoj kev sim
Xyoo 1911, physics twb muaj cov ntaub ntawv thawj zaug txog cov qauv ntawm cov teeb meem. Ernest Rutherford nrhiav tau qhov peb niaj hnub hu ua atomic nucleus.
Muaj teeb meem uas muaj qhov txawv txav: lawv spontaneously emits ntau yam, ob qho tib si zoo thiab tsis zoo. Cov tshuaj no hu ua radioactive. Cov ntsiab lus zoo Rutherford hu ua alpha hais (α-particles).
Lawv muaj tus nqi "+" sib npaug rau ob tus nqi qis (qα=+2e). Qhov hnyav ntawm cov ntsiab lus yog kwv yees li ntawm plaub pawg ntawm hydrogen atom. Rutherford tau npaj cov xov tooj cua uas tso tawm cov alpha thiab foob pob ua yeeb yaj kiab kub (cov ntawv ci) nrog lawv cov kwj deg.
Nws pom tias feem ntau α-cov ntsiab lus NW nyuam qhuav hloov lawv txoj kev coj thaum hla cov hlau atoms. Tab sis muaj tsawg heev uas deviate rov qab. Vim li cas qhov no tshwm sim? Paub txog lub physics ntawm cov qauv ntawm cov teeb meem, peb muaj peev xwm teb: vim nyob rau hauvkub atoms, zoo li lwm yam, muaj cov ntsiab lus zoo uas tawm tsam alpha hais. Tab sis vim li cas qhov no tsuas yog tshwm sim nrog ob peb lub ntsiab lus? Vim hais tias qhov loj ntawm qhov zoo them ib feem ntawm lub atom yog ntau me dua nws tus kheej. Rutherford tau los xaus qhov no. Nws hu ua qhov zoo nqi ntawm lub atom lub nucleus.
Lub cuab yeej ntawm atom
Physics ntawm cov qauv ntawm cov teeb meem: Molecules yog tsim los ntawm atoms, uas muaj ib tug me me zoo them ib feem (nucleus) ncig los ntawm electrons. Qhov nruab nrab ntawm lub atom yog piav qhia los ntawm qhov tseeb tias tag nrho cov nqi tsis zoo ntawm cov electrons yog sib npaug rau qhov zoo - lub nucleus. qcore+ qel=0. Vim li cas ho tsis electrons poob ntawm lub nucleus, vim lawv nyiam? Txhawm rau teb cov lus nug no, Rutherford tau hais tias lawv tig zoo li lub ntiaj teb txav mus los ntawm lub hnub thiab tsis txhob sib tsoo nrog nws. Nws yog lub zog uas tso cai rau qhov system no kom ruaj khov. Rutherford tus qauv ntawm lub atom hu ua planetary.
Yog hais tias lub atom yog nruab nrab, thiab tus naj npawb ntawm electrons nyob rau hauv nws yuav tsum yog integer, ces tus nqi ntawm lub nucleus yog sib npaug rau tus nqi no nrog ib tug ntxiv kos npe rau. qcores=+ze. z yog tus naj npawb ntawm electrons nyob rau hauv nruab nrab atom. Hauv qhov no, tus nqi tag nrho yog xoom. Yuav ua li cas nrhiav tau tus naj npawb ntawm electrons hauv ib lub atom? Koj yuav tsum tau siv lub sij hawm ntev ntawm cov ntsiab lus. Qhov ntev ntawm ib lub atom yog qhov kev txiav txim ntawm 10-10 m. Thiab cov nuclei yog 100 txhiab zaus me - 10-15 m.
Cia peb xav tias peb nce qhov loj ntawm cov tub ntxhais mus rau 1 meter. Hauv ib qho khoom, qhov kev ncua deb ntawm atoms yog kwv yees li sib npaug ntawm qhov loj ntawm lawv tus kheej, uas txhais tau hais tias qhov ntevyuav nce mus txog 105, uas yog 100 km. Ntawd yog, lub atom yog xyaum tsis muaj dab tsi, uas yog vim li cas cov alpha hais feem ntau ya los ntawm cov ntawv ci uas yuav luag tsis muaj deflection.
qauv ntawm lub nucleus
Lub physics ntawm cov qauv ntawm cov teeb meem yog xws li lub nucleus muaj ob yam hais. Ib txhia ntawm lawv raug nqi zoo. Yog tias peb xav txog ib qho atom uas muaj peb lub tshuab hluav taws xob, tom qab ntawd hauv nws muaj peb qhov uas muaj qhov zoo. Lawv hu ua protons. Lwm cov ntsiab lus tsis muaj hluav taws xob - neutrons.
Qhov loj ntawm cov proton thiab neutron yog kwv yees li sib npaug. Ob qhov khoom muaj qhov hnyav ntau dua li ib qho hluav taws xob. mproton ≈ 1837mel. Tib yam siv rau qhov loj ntawm neutron. Cov lus xaus raws li qhov no: qhov hnyav ntawm qhov zoo thiab nruab nrab nqi yog qhov tseem ceeb uas txiav txim siab qhov loj ntawm lub atom. Protons thiab neutrons muaj lub npe nrov - nucleons. Qhov hnyav ntawm lub atom yog txiav txim los ntawm lawv tus lej, uas yog hu ua tus lej ntawm cov nucleus. Peb denoted tus naj npawb ntawm electrons nyob rau hauv ib lub atom los ntawm tsab ntawv z, tab sis vim nws yog nruab nrab, tus naj npawb ntawm zoo thiab tsis zoo hais yuav tsum sib phim. Yog li ntawd, z kuj tseem hu ua proton lossis tus lej nqi.
Yog tias peb paub tus lej thiab tus lej them, ces peb tuaj yeem nrhiav cov lej ntawm neutrons N. N=A - z. Yuav ua li cas thiaj paub tias muaj pes tsawg nucleon thiab protons nyob hauv lub nucleus? Nws hloov tawm hais tias nyob rau hauv lub sij hawm lub sij hawm, nyob ib sab ntawm txhua lub caij, muaj ib tug xov tooj uas chemists hu lub txheeb ze atomic mass.
Yog tias peb sib sau ua ke, peb tsis muaj dab tsi ntau dualoj tus naj npawb los yog tus naj npawb ntawm nucleon nyob rau hauv lub nucleus (A). Tus naj npawb atomic ntawm ib lub ntsiab yog tus naj npawb ntawm protons (z). Paub A thiab z, nws yog ib qho yooj yim mus nrhiav N - tus naj npawb ntawm neutrons. Yog hais tias lub atom yog nruab nrab, ces tus naj npawb ntawm electrons thiab protons yog sib npaug.
Isotopes
Muaj ntau yam ntawm cov nucleus uas tus naj npawb ntawm protons zoo ib yam, tab sis tus naj npawb ntawm cov neutrons yuav txawv (txhais tau tias tib yam tshuaj lom neeg). Lawv hu ua isotopes. Hauv qhov xwm txheej, atoms ntawm ntau hom sib xyaw, yog li cov kws tshuaj ntsuam xyuas qhov nruab nrab loj. Yog li ntawd, nyob rau hauv lub sij hawm lub sij hawm tus txheeb ze qhov hnyav ntawm ib tug atom yog ib txwm ib tug zauv feem. Cia peb xav seb yuav ua li cas tshwm sim rau lub atom nruab nrab yog tias ib qho hluav taws xob raug tshem tawm ntawm nws lossis, qhov sib txawv, ib qho ntxiv yog muab tso rau.
Ions
Xav txog qhov nruab nrab lithium atom. Muaj ib lub nucleus, ob lub electrons nyob ntawm ib lub plhaub thiab peb ntawm lwm qhov. Yog tias peb tshem tawm ib qho ntawm lawv, peb tau txais cov txiaj ntsig zoo. qcores =3rd. Cov hluav taws xob them nyiaj tsuas yog ob ntawm peb tus nqi qis, thiab peb tau txais ion zoo. Nws raug xaiv raws li hauv qab no: Li+. Ib qho ion yog ib qho atom uas tus naj npawb ntawm cov electrons tsawg dua los yog ntau dua li cov protons hauv lub nucleus. Hauv thawj kis, nws yog qhov zoo ion. Yog tias peb ntxiv ib qho hluav taws xob ntxiv, ces yuav muaj plaub ntawm lawv, thiab peb yuav tau txais qhov tsis zoo ion (Li-). Xws li yog lub physics ntawm cov qauv ntawm cov teeb meem. Yog li, lub atom nruab nrab txawv ntawm ib qho ion nyob rau hauv uas cov electrons nyob rau hauv nws kiag li them rau tus nqi ntawm lub nucleus.
