Qhov Tseem Ceeb Qhov txawv - Dipole-Dipole vs London Dispersion Forces
Dipole-dipole thiab London dispersion rog yog ob lub zog nyiam pom ntawm cov molecules lossis atoms; lawv ncaj qha cuam tshuam rau lub boiling point ntawm lub atom / molecule. Qhov sib txawv tseem ceeb ntawm Dipole-Dipole thiab London Dispersion rog yog lawv lub zog thiab qhov twg lawv tuaj yeem pom. Lub zog ntawm London dispersion rog yog qhov tsis muaj zog dua li kev sib cuam tshuam ntawm dipole-dipole; Txawm li cas los xij ob qho tib si ntawm cov kev nyiam no tsis muaj zog dua li ionic lossis covalent bonds. London dispersion rog tuaj yeem pom nyob rau hauv ib qho molecule lossis qee zaum hauv atoms, tab sis kev sib cuam tshuam ntawm dipole-dipole tsuas yog pom nyob rau hauv polar molecules.
Dipole-Dipole Force yog dab tsi?
Dipole-dipole kev sib cuam tshuam tshwm sim thaum ob qho tib si polarized molecules cuam tshuam los ntawm qhov chaw. Cov rog no muaj nyob rau hauv tag nrho cov molecules uas yog polar. Polar molecules yog tsim thaum ob lub atoms muaj qhov sib txawv electronegativity thaum lawv tsim ib daim ntawv cog lus. Hauv qhov no, atoms tsis tuaj yeem faib cov hluav taws xob sib npaug ntawm ob lub atom vim qhov sib txawv electronegativity. Qhov ntau electronegative atom attracts electron huab ntau tshaj qhov tsawg electronegative atom; yog li ntawd lub resulting molecule muaj me ntsis zoo kawg thiab me ntsis tsis zoo kawg. Qhov zoo thiab tsis zoo dipoles hauv lwm cov molecules tuaj yeem sib nyiam, thiab qhov kev nyiam no hu ua dipole-dipole rog.
London Dispersion Force yog dab tsi?
London dispersion rog yog suav tias yog lub zog tsis muaj zog tshaj plaws ntawm cov molecules uas nyob ib sab lossis atoms. London dispersion rog ua rau thaum muaj kev hloov pauv hauv electron faib hauv cov molecule lossis atom. Piv txwv li; Cov hom kev nyiam zog no tshwm sim nyob rau hauv cov atoms nyob sib ze vim yog ib qho dipole instantaneous ntawm ib qho atom. Nws induces dipole ntawm cov atoms nyob sib ze thiab ces attracts ib leeg los ntawm qaug zog attraction zog. Qhov loj ntawm London dispersion quab yuam nyob ntawm seb yuav ua li cas yooj yim electrons ntawm lub atom los yog nyob rau hauv lub molecule yuav polarized teb rau ib tug instantaneous quab yuam. Lawv yog lub zog ib ntus uas tej zaum yuav muaj nyob rau hauv ib qho molecule vim lawv muaj electrons.
Qhov txawv ntawm Dipole-Dipole thiab London Dispersion Forces yog dab tsi?
Definition:
Dipole-Dipole Force: Dipole-dipole quab yuam yog lub zog ntawm qhov zoo ntawm dipole ntawm lub ncov qaumteb qabteb molecule thiab qhov tsis zoo dipole ntawm lwm qhov oppositely polarized molecule.
London Dispersion Force: London dispersion quab yuam yog lub zog txaus nyiam ib ntus ntawm cov molecules uas nyob ib sab lossis atoms thaum muaj qhov hloov pauv ntawm cov khoom siv hluav taws xob.
Nature:
Dipole-Dipole Force: Dipole-dipole kev sib cuam tshuam muaj nyob hauv cov polar molecules xws li HCl, BrCl, thiab HBr. Qhov no tshwm sim thaum ob lub molecules sib koom cov electrons tsis sib npaug los ua ib daim ntawv cog lus. Lub electron ceev hloov mus rau ntau electronegative atom, ua rau me ntsis tsis zoo dipole ntawm ib kawg thiab me ntsis zoo dipole nyob rau hauv lwm yam kawg.
London Dispersion Force: London dispersion rog tuaj yeem pom nyob rau hauv ib qho atom lossis molecule; qhov yuav tsum tau muaj yog huab cua electron. London dispersion rog muaj nyob rau hauv tsis-polar molecules thiab atoms ib yam nkaus.
Zoo:
Dipole-Dipole Force: Dipole-dipole rog muaj zog dua li lub zog dispersion tab sis tsis muaj zog dua li ionic thiab covalent bonds. Qhov nruab nrab lub zog ntawm dispersion rog sib txawv ntawm 1-10 kcal / mol.
London Dispersion Force: Lawv tsis muaj zog vim London dispersion rog yog ib ntus rog (0-1 kcal / mol).
Cov Yam Tseem Ceeb:
Dipole-Dipole Force: Qhov cuam tshuam rau lub zog ntawm dipole-dipole rog yog electronegativity sib txawv ntawm cov atoms hauv cov molecule, molecular loj thiab cov duab ntawm lub molecule. Hauv lwm lo lus, thaum daim ntawv cog lus ntev nce qhov kev sib cuam tshuam dipole txo.
London Dispersion Force: Qhov loj ntawm London dispersion rog nyob ntawm ntau yam. Nws nce nrog tus naj npawb ntawm electrons hauv lub atom. Polarizability yog ib qho tseem ceeb uas cuam tshuam rau lub zog hauv London dispersion rog; nws yog lub peev xwm los distort lub electron huab los ntawm lwm atom/molecule. Cov molecules muaj tsawg dua electronegativity thiab loj radii muaj ntau dua polarizability. Qhov sib txawv; Nws yog ib qho nyuaj rau distort lub electron huab nyob rau hauv me me atoms vim electrons nyob ze heev rau lub nucleus.
Example:
| Atom | Boiling Point / oC | |
| Helium | (Nws) | -269 |
| (Ne) | -246 | |
| Argon | (Ar) | -186 |
| Krypton | (Kr) | -152 |
| Xenon | (Xe) | -107 |
| Redon | (Rn) | -62 |
Rn- Lub atom loj dua, yooj yim rau polarize (siab dua polarizability) thiab muaj lub zog txaus nyiam tshaj plaws. Helium yog me me thiab nyuaj rau distort thiab ua rau tsis muaj zog London dispersion rog.
