Qhov sib txawv tseem ceeb ntawm sigma thiab pi molecular orbitals yog sigma molecular orbital cov ntaub ntawv los ntawm kev sib tshooj ntawm atomic orbitals nyob rau hauv lub taub hau-rau-lub taub hau kev taw qhia raws lub internuclear axis, whereas pi molecular orbitals tsim los ntawm overlapping ntawm atomic orbitals. nyob rau hauv ib tug parallel direction.
Sigma thiab pi molecular orbitals yog ob hom molecular orbitals uas pab txhawb rau cov qauv ntawm cov tshuaj lom neeg. Cov molecular orbitals yog lub luag haujlwm rau kev tsim ib thiab ob lossis peb daim ntawv cog lus, raws li.
Molecular Orbitals yog dab tsi?
Atoms koom ua ke los tsim cov molecules. Thaum ob lub atom txav los ze zog ua ke los tsim ib lub molecule, atomic orbitals sib tshooj thiab ua ke los ua molecular orbitals. Tus naj npawb ntawm cov tsim tshiab molecular orbitals yog sib npaug rau cov naj npawb ntawm cov atomic orbitals ua ke. Tsis tas li ntawd, lub molecular orbital nyob ib ncig ntawm ob lub nuclei ntawm atoms, thiab cov electrons tuaj yeem txav mus los ntawm ob lub nuclei. Zoo ib yam li atomic orbitals, molecular orbitals ntau kawg muaj 2 electrons, uas muaj qhov sib txawv.
Ntxiv mus, muaj ob hom molecular orbitals li kev sib txuas molecular orbitals thiab antibonding molecular orbitals. Bonding molecular orbitals muaj electrons nyob rau hauv lub xeev av, thaum antibonding molecular orbitals tsis muaj electrons hauv av. Tsis tas li ntawd, cov khoom siv hluav taws xob tuaj yeem tuav cov tshuaj tiv thaiv orbitals yog tias cov molecule nyob hauv lub xeev zoo siab.
Sigma Molecular Orbitals yog dab tsi?
Sigma molecular orbitals yog hom hybrid orbitals uas tsim los ntawm kev sib tshooj ntawm ob lub atomic orbitals los ntawm lub taub hau-rau-lub taub hau raws li cov axis internuclear. Feem ntau, thawj covalent daim ntawv cog lus ntawm ob lub atom yog ib txwm ib daim ntawv cog lus sigma. Overlapping ntawm ob atomic orbitals nyob rau hauv inter-nuclear axis tsim ib tug sigma covalent daim ntawv cog lus. Nyob rau hauv ib tug sigma molecular orbital, lub electron ceev nyob rau hauv nruab nrab ntawm lub molecular orbital yog siab yog hais tias ob lub atoms uas lub atomic orbitals sib tshooj yog zoo tib yam.
Daim duab 01: Hydrogen Molecule
Thaum xav txog hydrogen ua piv txwv, sigma molecular orbital cov ntaub ntawv los ntawm kev sib tshooj ntawm ob 1s atomic orbitals los ntawm txhua hydrogen atom. Peb tuaj yeem ua luv luv no sigma daim ntawv cog lus li σ. Ntawm no, qhov sib koom electron ceev tshwm sim ncaj qha nruab nrab ntawm cov atoms sib txuas raws li kev sib txuas axis. Qhov no ua rau muaj kev cuam tshuam ruaj khov ntawm ob lub atoms sib txuas nrog rau cov khoom siv hluav taws xob piv rau kev ruaj ntseg ntawm cov atoms sib cais. Feem ntau, daim ntawv cog lus sigma yog thawj daim ntawv cog lus uas tsim ntawm ob lub atoms.
Pi Molecular Orbitals yog dab tsi?
Pi molecular orbitals yog hom hybrid orbitals uas tsim los ntawm kev sib tshooj ntawm ob lub atomic orbitals nyob rau hauv qhov sib npaug. Ntawm no, qhov sib txuas ntawm electron ceev tshwm sim saum toj no thiab hauv qab ntawm lub axis internuclear. Tsis tas li ntawd, peb tsis tuaj yeem soj ntsuam cov hluav taws xob ntawm cov axis sib txuas. Hom kev sib cuam tshuam ntawm ob lub atoms no ua rau muaj kev ruaj khov dua li kev ruaj ntseg ntawm cov atoms sib cais. Feem ntau, cov khoom siv hluav taws xob zoo li nyob hauv hom molecular orbitals thaum muaj hluav taws xob txaus nyob hauv cov atoms. Pi molecular orbitals ib txwm tsim ua thib ob lossis thib peb molecular orbital tsim hais txog kev sib txuas ntawm ob lub atoms vim tias sigma molecular orbital yog thawj molecular daim ntawv cog lus los tsim ntawm ob lub atoms.
Daim duab 02: Pi Molecular Orbitals
Ntxiv mus, tus naj npawb ntawm cov atoms uas ua rau lub p atomic orbital ntawm lub pi system yeej ib txwm sib npaug rau cov pi molecular orbitals tam sim no nyob rau hauv ib daim ntawv cog lus tshuaj. Feem ntau, qhov qis tshaj pi molecular orbital muaj xoom ntsug nodes uas twb muaj lawm. Ntawm no, kev ua tiav pi molecular orbitals tau txais ib qho ntxiv ntsug ntawm qhov nce lub zog. Peb tuaj yeem ua luv luv pi molecular orbital li π.
Qhov txawv ntawm Sigma thiab Pi Molecular Orbitals yog dab tsi?
Sigma thiab pi molecular orbitals yog ob hom molecular orbitals uas pab txhawb rau cov qauv ntawm cov tshuaj lom neeg. Qhov sib txawv tseem ceeb ntawm sigma thiab pi molecular orbitals yog sigma molecular orbital cov ntaub ntawv los ntawm kev sib tshooj ntawm atomic orbitals nyob rau hauv lub taub hau-rau-lub taub hau kev taw qhia raws lub internuclear axis, whereas pi molecular orbitals tsim los ntawm overlapping ntawm atomic orbitals nyob rau hauv ib tug parallel kev taw qhia.
Cov infographic hauv qab no teev qhov sib txawv ntawm sigma thiab pi molecular orbitals hauv daim ntawv tabular rau ib sab ntawm kev sib piv.
Summary – Sigma vs Pi Molecular Orbitals
A molecular orbital yog ib hom orbital uas tsim los ntawm kev sib tshooj ntawm atomic orbitals. Qhov sib txawv tseem ceeb ntawm sigma thiab pi molecular orbitals yog sigma molecular orbital cov ntaub ntawv los ntawm kev sib tshooj ntawm atomic orbitals nyob rau hauv lub taub hau-rau-lub taub hau kev taw qhia raws lub internuclear axis, whereas pi molecular orbitals tsim los ntawm overlapping ntawm atomic orbitals nyob rau hauv ib tug parallel kev taw qhia.
