Q.

A hydrogen bond is a weak electrostatic force of attraction that occurs between a hydrogen atom covalently bonded to a highly electronegative atom (such as fluorine, oxygen, or nitrogen) and another electronegative atom of the same or different molecule. Hydrogen bonding plays a crucial role in determining the physical and chemical properties of substances.

Types of Hydrogen Bonding (Class 11)

There are two main types of hydrogen bonding, which are as follows:

1. Intermolecular Hydrogen Bonding

Intermolecular hydrogen bonding occurs between hydrogen atoms and electronegative atoms of different polar molecules. This type of bonding is responsible for many physical properties, such as high boiling point and melting points in water and other compounds.

Examples: Water (H₂O), Hydrogen Fluoride (HF), and Ammonia (NH₃)

        H - F        -    -        H - F        -    -        H - F    

2. Intramolecular Hydrogen Bonding

Intramolecular hydrogen bonding occurs within the same molecule when a hydrogen atom is attracted to an electronegative atom present in a nearby functional group. This type of bonding is common in molecules where functional groups are positioned closely, such as in ortho-substituted aromatic compounds.

Examples: Ortho-nitrophenol, Ortho-hydroxybenzaldehyde

Significance of Hydrogen Bonding

The concept of types of hydrogen bonding class 11 is significant in understanding molecular interactions and their effects on physical and chemical properties. For instance:

• Intermolecular hydrogen bonding contributes to water's unique properties, such as its high surface tension and boiling point.
• Intramolecular hydrogen bonding affects the solubility and stability of certain organic compounds.