Final answer:
Hydrogen bonds occur when a hydrogen atom attached to an electronegative atom gains a partial positive charge and is attracted to a partial negative charge on a nearby electronegative atom, forming a weak and transient interaction.
Step-by-step explanation:
Why Do Hydrogen Bonds Occur?
Hydrogen bonds occur when a hydrogen atom that is covalently bonded to a highly electronegative atom such as fluorine, oxygen, or nitrogen, acquires a slight positive charge. This happens because these electronegative atoms attract the shared electron pair more strongly, leaving hydrogen electron-deficient. Hence, the hydrogen atom becomes a 'partial positive' (δ+) and can form a weak interaction with another nearby electronegative atom that has a 'partial negative' (δ-) charge, typically located on a different molecule or within the same molecule. The interaction formed is known as a hydrogen bond, which, despite being individually weak, can combine in large numbers to exert significant effects, such as giving water its unique properties and stability to the structure of DNA and proteins. One of the most common examples of hydrogen bonding is found between water molecules, which is critical for many of life's processes. The weakly negative oxygen atom in one water molecule is attracted to the weakly positive hydrogen atoms in another, allowing multiple hydrogen bonds to form that are essential for water's liquidity and high boiling point.