Hydrogen bonding - the bond is formed when_ in a molecule is attracted to an oxygen molecule

hydrogen bond is formed when hydrogen in a molecule is attracted to an oxygen atom or more electronegative element such as chlorine etc.

Hydrogen in a molecule

Explanation:

When an electrostatic force of atom of Hydrogen gets attracted to an electronegative force of atom or group, such as - Oxygen and nitrogen, the Hydrogen bond is constructed. It forms when the substance of positive charged molecule with polar covalent bond is merged with a negative charge.

These bonds are weak because they are formed fast and break easily. They are remarkable for biological system, as they explain the different properties of water. Hydrogen bonds are useful to make the structure of proteins and nucleic acids and to stabilize them.