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Unformatted text preview: ion. • Nonpolar covalent bond: equal sharing of electrons; atoms of equal electronegativity (O=O, N=N, C=C) or very close, as in the ‐C‐H bond. • Polar covalent bond: unequal sharing; disparity in electronegativity between atoms: ‐O‐H, ‐N‐H, ‐C=O, ‐C‐N Polar Covalent Bonds Consider the ‐O‐H bond below: The unequal sharing of electrons in this polar covalent bond creates a partial negative charge around the more electronegative atom (oxygen), and a partial positive charge around the less electronegative atom (hydrogen): Partial charges H • • • • O δ+ O H • • • • δ‐ loses negative charge charge gains negative charge • Molecules possessing such bonds are termed polar molecules, and are hydrophilic in nature. – Associate with other polar molecules, ions, & charged molecules – Hydrophilic: refers to behavior in water; polar molecules readily associate with water molecules. – Polar molecules exclude nonpolar ones. – Some molecules may possess polar regions (proteins, lipids) Non‐polar Covalent Bonds • Nonpolar molecules, or nonpolar regions of molecules, possess nonpolar covalent bonds. – Such molecules or regions are hydrophobic; they repel polar water molecules and associa...
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This note was uploaded on 08/16/2011 for the course BIOL 1361-1362 taught by Professor Any during the Spring '08 term at University of Houston.

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