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Hydrogen bonds may be either symmetric or unsymmetric. In a symmetric hydrogen bond, the H atoms lies midway between the two other atoms. This arrangement is rare, but occurs in F-H<sup>...</sup>F<sup>-</sup>, where both bond lengths are 120 pm. more common is the unsymmetrical arrangement, where the A-H bond is shorter than the H<sup>...</sup>B bond. Simple electrostatic arguments, treating A-H<sup>...</sup>B as an array of point charges (partial negative charges on A and B, partial positive on H) suggest that the lowest energy is achieved when the bond is linear, because then the two partial negative charges are furthest apart. The experimental evidence from structural studies support a linear or near-linear arrangement.
Hydrogen bonds may be either symmetric or unsymmetric. In a symmetric hydrogen bond, the H atoms lies midway between the two other atoms. This arrangement is rare, but occurs in F-H<sup>...</sup>F<sup>-</sup>, where both bond lengths are 120 pm. more common is the unsymmetrical arrangement, where the A-H bond is shorter than the H<sup>...</sup>B bond. Simple electrostatic arguments, treating A-H<sup>...</sup>B as an array of point charges (partial negative charges on A and B, partial positive on H) suggest that the lowest energy is achieved when the bond is linear, because then the two partial negative charges are furthest apart. The experimental evidence from structural studies support a linear or near-linear arrangement.
Hydrogen bonds are relatively weak, especially compared with [[metallic bond|metallic]], [[ionic bond|ionic]] or [[covalent]] bonds. They are stronger than [[van der Waals force]]s.
Hydrogen bonds are relatively weak, especially compared with [[metallic bond|metallic]], [[ionic bond|ionic]] or [[covalent bond]]s. They are stronger than [[van der Waals force]]s.
[[Category:Chemical bonding]]
[[Category:Chemical bonding]]