Hydrogen Bond vs Covalent Bond
Tshuaj tua kab mob tuav cov atom thiab molecules ua ke. Bonds yog ib qho tseem ceeb hauv kev txiav txim siab txog tshuaj thiab lub cev tus cwj pwm ntawm molecules thiab atoms. 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 daim ntawv cog lus yog ib daim ntawv cog lus tshuaj uas txuas cov atoms hauv cov tshuaj sib txuas. Hydrogen bonds yog qhov chaw sib txuas ntawm cov molecules.
Hydrogen Bonds
Thaum hydrogen txuas rau lub atom electronegative xws li fluorine, oxygen lossis nitrogen, qhov kev sib txuas ntawm cov polar yuav tshwm sim. Vim hais tias ntawm electronegativity, cov electrons nyob rau hauv daim ntawv cog lus yuav ntau attracted rau lub electronegative atom tshaj hydrogen atom. Yog li ntawd, hydrogen atom yuav tau txais ib feem zoo nqi, qhov ntau electronegative atom yuav tau txais ib feem tsis zoo nqi. Thaum ob lub molecules uas muaj qhov sib cais ntawm cov nqi no nyob ze, yuav muaj lub zog txaus nyiam ntawm hydrogen thiab cov atom uas tsis zoo. Qhov kev nyiam no hu ua hydrogen bonding. Hydrogen bonds kuj muaj zog dua lwm cov kev sib cuam tshuam dipole, thiab lawv txiav txim siab tus cwj pwm molecular. Piv txwv li, dej molecules muaj intermolecular hydrogen bonding. Ib qho dej molecule tuaj yeem tsim plaub hydrogen bonds nrog rau lwm cov dej molecule. Txij li cov pa oxygen muaj ob leeg ib leeg, nws tuaj yeem tsim ob daim ntawv cog lus hydrogen nrog cov khoom siv zoo hydrogen. Tom qab ntawd ob lub molecules dej tuaj yeem raug hu ua dimer. Txhua lub molecule dej tuaj yeem sib txuas nrog plaub lwm cov molecules vim tias muaj peev xwm sib txuas nrog hydrogen. Qhov no ua rau muaj qhov kub siab dua rau cov dej, txawm tias cov dej molecule muaj qhov hnyav molecular. Yog li ntawd, lub zog xav tau los rhuav tshem cov hydrogen bonds thaum lawv mus rau theem gaseous siab. Tsis tas li ntawd, hydrogen bonds txiav txim siab cov qauv siv lead ua ntawm cov dej khov. Cov txheej txheem tshwj xeeb ntawm cov dej khov nab kuab pab nws ntab rau hauv dej, yog li tiv thaiv cov dej hauv dej hauv lub caij ntuj no. Tsis tas li ntawd, hydrogen bonding plays lub luag haujlwm tseem ceeb hauv cov kab ke lom neeg. Cov qauv peb-dimensional ntawm cov protein thiab DNA tsuas yog ua raws li hydrogen bonds. Hydrogen bonds tuaj yeem rhuav tshem los ntawm cov cua sov thiab cov tshuab ua haujlwm.
Covalent Bonds
Thaum ob lub atoms zoo sib xws los yog tsawg heev electronegativity sib txawv ua ke, lawv tsim ib daim ntawv cog lus los ntawm kev sib koom electrons. Ob lub atoms tuaj yeem tau txais cov roj hluav taws xob hluav taws xob zoo los ntawm kev sib koom electrons hauv txoj kev no. Molecule yog cov khoom uas tshwm sim los ntawm kev tsim ntawm covalent bonds ntawm atoms. 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 covalent daim ntawv cog lus. Methane molecule (CH4) kuj muaj covalent bonds ntawm carbon thiab hydrogen atoms. Methane yog ib qho piv txwv rau cov molecule uas muaj covalent bonds ntawm atoms uas tsis tshua muaj electronegativity sib txawv.
Qhov txawv ntawm Hydrogen thiab Covalent Bonds yog dab tsi?
• Covalent bonds tshwm sim ntawm cov atoms los tsim cov molecule. Hydrogen bonds tuaj yeem pom ntawm cov molecules.
• Hydrogen atom yuav tsum nyob ntawd kom muaj hydrogen daim ntawv cog lus. Covalent bonds tuaj yeem tshwm sim ntawm ob lub atoms.
• Covalent bonds muaj zog dua li hydrogen bonds.
• Hauv kev sib koom ua ke, cov hluav taws xob sib koom ntawm ob lub atom tab sis, hauv hydrogen bonding, qhov kev sib koom no tsis tshwm sim; es ib qho kev cuam tshuam electrostatic ntawm tus nqi zoo thiab tus nqi tsis zoo tshwm sim.
