Valence Electrons yog dab tsi?
Pendahuluuan
Hauv kev tshuaj lom neeg, lo lus "valence electrons" yog lub tswv yim tseem ceeb uas tseem ceeb heev rau kev nkag siab. Valence electrons tsis yog tsuas yog ua lub luag haujlwm tseem ceeb hauv kev txiav txim siab txog cov khoom siv tshuaj lom neeg ntawm ib qho khoom xwb tab sis kuj tseem cuam tshuam rau cov tshuaj lom neeg thiab kev ruaj khov ntawm cov tshuaj sib xyaw. Tsab xov xwm no yuav tshawb nrhiav tob txog cov valence electrons yog dab tsi, vim li cas lawv thiaj tseem ceeb, lawv faib li cas hauv ib lub atom, thiab lub tswv yim no siv li cas hauv ntau qhov chaw ntawm chemistry.
Kev Txhais Lus ntawm Valence Electrons
Cov electrons Valence yog cov electrons pom nyob rau hauv lub plhaub sab nraud ntawm ib lub atom thiab koom nrog hauv kev tsim cov tshuaj sib txuas. Ntau dua li kev siv tshuab, cov electrons no nyob rau theem siab tshaj plaws ntawm ib lub atom thiab, yog li, yog lub luag haujlwm rau kev sib cuam tshuam ntawm cov atoms hauv kev tsim cov molecules. Valence electrons tuaj yeem pom nyob rau hauv lub plhaub s thiab p sab nraud tshaj plaws hauv cov ntaub ntawv ntawm cov ntsiab lus tseem ceeb (A) thiab hauv lub plhaub d sab nraud tshaj plaws hauv cov ntsiab lus hloov pauv.
Qhov Tseem Ceeb ntawm Valence Electrons
Valence electrons ua ntau lub luag haujlwm tseem ceeb hauv chemistry:
1. Kev Tsim Cov Chemical Bonds: Valence electrons muaj feem cuam tshuam ncaj qha rau kev tsim cov covalent, ionic, thiab metallic bonds.
– Cov Kev Sib Txuas Covalent: Hauv ib qho tshuaj sib txuas covalent, ob lub atoms sib koom ib khub ntawm cov electrons valence. Piv txwv li, hauv H2O (dej) molecule, ib lub hydrogen atom sib koom cov electrons nrog ib lub oxygen atom.
– Kev Sib Txuas Ionic: Hauv cov tshuaj ionic, cov electrons valence los ntawm ib lub atom raug xa mus rau lwm lub atom, tsim cov cations thiab anions. Piv txwv li, hauv sodium chloride (ntsev), sodium pub nws cov electrons rau chlorine.
– Kev Sib Txuas Hlau: Hauv kev sib txuas hlau, cov electrons valence tuaj yeem txav mus los tau yooj yim ntawm cov hlau ions, tsim kom muaj cov qauv siv lead ua los ntawm hlau thiab ua lub luag haujlwm rau cov khoom xws li hluav taws xob thiab thermal conductivity.
2. Kev Ua Haujlwm Tshuaj: Cov electrons valence txiav txim siab seb ib lub ntsiab lus ua haujlwm li cas nrog lwm cov ntsiab lus. Qhov yooj yim dua uas ib lub atom poob, tau txais, lossis sib koom cov electrons valence, qhov ntau dua uas lub ntsiab lus ua haujlwm. Piv txwv li, cov hlau alkali (xws li sodium) ua haujlwm tau zoo heev vim tias lawv tsuas muaj ib lub electron valence uas tuaj yeem poob tau yooj yim.
3. Cov Khoom Siv Lub Cev thiab Tshuaj: Cov electrons valence cuam tshuam rau cov khoom siv lub cev (xws li cov ntsiab lus yaj thiab cov ntsiab lus kub) thiab cov khoom siv tshuaj (xws li acidity lossis basicity) ntawm ib qho tshuaj. Piv txwv li, cov atoms uas muaj cov qauv valence electron puv ntau dua feem ntau ruaj khov dua thiab tsis tshua muaj kev cuam tshuam.
Kev Faib Tawm ntawm Valence Electron
Cov electrons valence nyob rau hauv lub plhaub sab nraud tshaj plaws ntawm ib lub atom thiab tuaj yeem txheeb xyuas tau siv lub rooj teev cov khoom sib xyaw. Tus lej pawg (kab ntsug) hauv lub rooj teev cov khoom sib xyaw qhia txog tus lej ntawm cov electrons valence uas ib lub ntsiab muaj.
– Cov Pab Pawg Tseem Ceeb: Yog tias cov ntsiab lus koom nrog pawg tseem ceeb (A), tus lej pawg sib raug rau tus lej ntawm cov electrons valence. Piv txwv li, cov ntsiab lus hauv pawg 1A (xws li hydrogen thiab lithium) muaj ib lub electron valence. Cov ntsiab lus hauv pawg 7A (xws li fluorine thiab chlorine) muaj xya lub electrons valence.
– Cov Ntsiab Lus Hloov: Rau cov ntsiab lus hloov, tus naj npawb ntawm cov electrons valence nyuaj dua vim tias lawv cuam tshuam nrog d subshell. Txawm hais tias muaj kev hloov pauv, feem ntau cov ntsiab lus hloov muaj ob lub electrons valence los ntawm sab nraud tshaj plaws s subshell thiab qee qhov ntxiv los ntawm d subshell.
Kev Teeb tsa Valence Electron
Qhov kev teeb tsa ntawm cov electron valence tuaj yeem txiav txim siab los ntawm kev sau tag nrho cov electron configuration ntawm ib lub atom thiab txheeb xyuas cov electrons hauv lub plhaub sab nraud tshaj plaws. Piv txwv li:
– Chlorine Atom (Cl): Tus lej atomic ntawm chlorine yog 17. Nws cov qauv hluav taws xob yog 1s² 2s² 2p⁶ 3s² 3p⁵. Cov electrons valence ntawm chlorine yog 3s² 3p⁵, yog li chlorine muaj xya valence electrons.
– Potassium Atom (K): Potassium tus lej atomic yog 19. Nws cov electron configuration yog 1s² 2s² 2p⁶ 3s² 3p⁶ 4s¹. Potassium tus valence electron yog 4s¹, yog li potassium muaj ib qho valence electron uas yooj yim tso tawm.
Piv txwv thiab Daim Ntawv Thov ntawm Valence Electrons
1. Cov Tshuaj Tiv Thaiv Acid-Base: Hauv cov tshuaj tiv thaiv acid-base, cov protons (H⁺) feem ntau txav ntawm cov kua qaub mus rau lub hauv paus, uas cuam tshuam nrog kev sib cuam tshuam ntawm cov electrons valence. Cov kua qaub xws li HCl muaj cov electrons valence uas yooj yim tso tawm, thaum cov hauv paus xws li NH3 muaj cov electrons valence uas tuaj yeem nyiam cov protons.
2. Kev Ua Hluav Taws Xob: Cov hlau xws li tooj liab thiab txhuas muaj cov electrons valence uas xoob thiab tuaj yeem txav mus los tau yooj yim, ua rau cov hlau ua hluav taws xob tau zoo.
3. Pi Bond thiab Sigma Bond: Hauv cov organic chemistry, pi thiab sigma bonds yog tsim los ntawm kev sib cuam tshuam ntawm valence electrons. Piv txwv li, hauv ethylene (C2H4), ob chav bond ntawm cov carbon atoms muaj ib qho sigma bond thiab ib qho pi bond, txhua tus tsim los ntawm valence electrons.
4. Cov Catalysts: Hauv catalysis, txawm tias homogeneous lossis heterogeneous, cov valence electrons ntawm cov catalyst cuam tshuam nrog cov reactants kom txo qis lub zog ua haujlwm ntawm cov tshuaj tiv thaiv. Ib qho piv txwv classic yog kev siv platinum ua cov catalyst hauv cov tshuaj tiv thaiv hydrogenation.
Xaus
Cov hluav taws xob valence yog lub tswv yim tseem ceeb hauv chemistry uas pab piav qhia ntau yam xwm txheej, suav nrog kev ua haujlwm tshuaj lom neeg, cov khoom siv lub cev ntawm cov tshuaj, thiab cov txheej txheem ua haujlwm. Kev nkag siab txog cov hluav taws xob valence thiab lawv qhov kev faib tawm hauv cov atoms yog qhov tseem ceeb rau kev nkag siab txog cov ntsiab lus thiab cov tshuaj sib cuam tshuam li cas. Qhov no tseem ceeb tsis yog rau kev tshuaj lom neeg yooj yim xwb tab sis kuj rau kev siv ua haujlwm hauv kev tshawb fawb txog cov ntaub ntawv, biochemistry, thiab lwm yam kev tshawb fawb siv. Los ntawm kev txhawb nqa lub tswv yim no, cov kws tshawb fawb thiab cov tub ntxhais kawm yuav muaj peev xwm nkag siab zoo dua thiab siv cov khoom siv tshuaj rau ntau yam kev tshawb fawb thiab kev lag luam.
