Polar vs Nonpolar Covalent Bonds
Raws li tau hais los ntawm American chemist G. N. Lewis, atoms ruaj khov thaum lawv muaj yim electrons hauv lawv lub plhaub valence. Feem ntau ntawm cov atoms muaj tsawg tshaj li yim electrons nyob rau hauv lawv valence shells (tshwj tsis yog cov noble gases nyob rau hauv pab pawg neeg 18 ntawm lub periodic rooj); yog li ntawd, lawv tsis ruaj khov. Cov atoms no zoo li ua rau ib leeg, ua kom ruaj khov. Yog li, txhua lub atom tuaj yeem ua tiav cov roj hluav taws xob hluav taws xob zoo. Covalent bonds yog ib hom tshuaj lom neeg loj, uas txuas atoms hauv cov tshuaj lom neeg. Muaj ob hom covalent bonds uas tsis yog-polar thiab polar covalent bonds.
Polar Covalent Bond yog dab tsi?
Polarity tshwm sim vim qhov sib txawv ntawm electronegativity. Electronegativity muab ib qho kev ntsuas ntawm ib lub atom kom nyiam electrons nyob rau hauv ib daim ntawv cog lus. Feem ntau Pauling nplai yog siv los qhia txog qhov tseem ceeb ntawm electronegativity. Yog tias qhov sib txawv ntawm electronegativity ntawm ob lub atoms loj heev (ntau tshaj 1.7), ces daim ntawv cog lus yuav yog ionic. Rau ib daim ntawv cog lus los ua ib tug polar covalent daim ntawv cog lus, qhov sib txawv electronegativity yuav tsum tsis pub tshaj tus nqi 1.7. Nyob ntawm qhov sib txawv ntawm electronegativity, covalent cim tuaj yeem hloov pauv. Qhov kev sib txawv no yuav siab dua lossis qis dua. Yog li ntawd, daim ntawv cog lus electron khub yog rub ntau dua los ntawm ib lub atom piv rau lwm lub atom, uas yog koom nrog hauv kev ua daim ntawv cog lus. Qhov no yuav ua rau muaj kev faib tsis sib npaug ntawm cov hluav taws xob ntawm ob lub atoms, thiab cov hom kev sib cog lus no hu ua polar covalent bonds. Vim tias qhov sib faib tsis sib luag ntawm cov hluav taws xob, ib lub atom yuav muaj qhov tsis zoo me ntsis thaum lwm lub atom yuav muaj qhov zoo me ntsis. Hauv qhov piv txwv no, peb hais tias cov atoms tau txais ib feem tsis zoo lossis qhov zoo. Lub atom nrog lub siab dua electronegativity tau txais qhov tsis zoo me ntsis, thiab lub atom nrog qis electronegativity yuav tau txais qhov zoo me ntsis. Polarity txhais tau tias kev sib cais ntawm cov nqi. Cov molecules no muaj lub sijhawm dipole. Dipole lub sijhawm ntsuas qhov polarity ntawm daim ntawv cog lus, thiab nws feem ntau ntsuas hauv debyes (nws kuj muaj kev taw qhia).
Non-Polar Covalent Bond yog dab tsi?
Thaum ob ntawm tib lub atom lossis atoms muaj tib lub electronegativity tsim ib daim ntawv cog lus ntawm lawv, cov atoms rub cov electron khub zoo ib yam. Yog li ntawd, lawv nyiam sib koom cov electrons, thiab hom kev sib cog lus no hu ua non-polar covalent bonds. Piv txwv li, thaum tib atoms koom ua ke los tsim cov molecules xws li Cl2, H2, los yog P4., txhua lub atom raug khi rau lwm tus los ntawm daim ntawv cog lus uas tsis yog-polar.
Qhov txawv ntawm Polar Covalent thiab Tsis-Polar Covalent Bonds yog dab tsi?
• Covalent bonds, uas tsis yog-polar, yog tsim los ntawm ob lub atoms nrog electronegativities zoo sib xws. Polar covalent bonds yog tsim los ntawm ob lub atom nrog electronegativities sib txawv (tab sis qhov sib txawv yuav tsum tsis pub tshaj 1.7).
• Nyob rau hauv cov tsis-polar covalent daim ntawv cog lus, electrons sib npaug sib koom los ntawm ob lub atoms koom ua cov ntawv cog lus. Nyob rau hauv polar covalent, cov electron khub yog rub ntau dua los ntawm ib lub atom piv rau lwm lub atom. Yog li qhov sib koom electron tsis sib npaug.
• Nyob rau hauv polar covalent daim ntawv cog lus, cov atoms muaj ib nrab nqi zoo thiab tsis zoo, tab sis nyob rau hauv non-polar bonds, tsis muaj ib feem nqi rau atoms.
• Polar covalent daim ntawv cog lus muaj lub sijhawm dipole, qhov tsis yog-polar covalent daim ntawv cog lus tsis muaj.
