Hydrogen+Bonding

Hydrogen Bond
Hydrogen bonds are intermolecular electrostatic interaction involving partial charges on H atoms. It is the attractive interaction of a hydrogen atom with a very electronegative atom. Nitrogen, Oxygen or fluorine are the only atoms that can be compatible with hydrogen bonding. The hydrogen bond is stronger than a van der Waals interaction, but weaker than covalent or ionic bonds. Hydrogen bonding occurs in inorganic molecules and is also important in organic molecules, like DNA. Intermolecular hydrogen bonding is responsible for the high boiling point of water, which is 100 degrees C. Intermolecular hydrogen bonding is partly responsible for the secondary, tertiary, and quaternary structures of proteins and nucleic acids. It also plays an important role in the structure of polymers. The exact number of hydrogen bonds formed by a molecule of liquid water fluctuates with time and depends on the temperature. From TIP4P liquid water simulations at 25 °C, it was estimated that each water molecule participates in an average of 3.59 hydrogen bonds. Where the bond strengths are more equivalent, one might instead find the atoms of two interacting water molecules partitioned into two polyatomic ions of opposite charge, specifically hydroxide (OH−) and hydronium (H3O+). (Hydronium ions are also known as 'hydroxonium' ions.) H−O− H3O+