Polar Covalent Bonds - Polar Covalent Bonds Bond Polarity...

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Polar Covalent Bonds Bond Polarity Electrons in covalent bonds are not always equally shared by the bonded atoms. In bonds that join two identical groups like the C-C bond in ethane, CH 3 -CH 3 , the electrons are equally shared. Thus, one end of the bond does not develop a negative charge while the opposite end is positive. The bond is non- polar. But when atoms of different elements are bonded, an electronegativity difference causes the shared electrons to be attracted more strongly by the more electronegative atom and a polar covalent bond results. An important case is that of acetone shown below. In acetone the four shared electrons of the C=O bond are more strongly attracted by oxygen polarizing the bond. Acetone has excess negative charge on oxygen and excess positive charge on its "carbonyl" carbon. This polarity is the result of the electronegativity difference between the bonded atoms. Polarity in acetone can be detected by measurement of its dipole moment which equals 2.88 D in the gas phase. The Importance of Bond Polarity
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This note was uploaded on 02/10/2010 for the course CHEM 261 taught by Professor Kropp during the Spring '10 term at University of North Carolina Wilmington.

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Polar Covalent Bonds - Polar Covalent Bonds Bond Polarity...

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