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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 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.
- Spring '08