why is hydrogen bonding inly possible with hydrogen?
It's the arrangement of the O-H bond. The oxygen is quite electronegative and pulls the electrons shared between O and H toward it, making it more negative and making the H partially positive. So the O atoms are attracted to the H atoms of other molecules (those attached to O). H bonding also occurs from other electronegative atoms; namely, N and F. Atoms with lower electronegativities (all other atoms except N, F, O) are too low to show this property.
Hydrogen bonding is a special type of intermolecular force that occurs between a hydrogen atom bonded to a highly electronegative atom (such as oxygen, nitrogen, or fluorine) and an electronegative atom in a neighboring molecule. It is called hydrogen bonding because it involves the hydrogen atom as the bridge between the two molecules.
The reason hydrogen bonding is only possible with hydrogen is primarily due to the unique properties of hydrogen atom. Hydrogen is the smallest and lightest element on the periodic table, consisting of only one proton and one electron. This makes it highly electronegative and able to form relatively strong polar covalent bonds with other elements.
When hydrogen is covalently bonded to an electronegative atom, such as oxygen in a water molecule (H2O), the electron density is unequally distributed within the molecule. The oxygen atom attracts the shared electrons more strongly, creating a partial negative charge (δ-) on the oxygen atom and a partial positive charge (δ+) on the hydrogen atom. This partial positive charge on the hydrogen atom allows it to interact with other electronegative atoms in nearby molecules.
The strength of hydrogen bonding arises from the large difference in electronegativity between hydrogen and other elements, which allows for a significant partial positive charge on hydrogen. This creates a strong electrostatic attraction between the δ+ hydrogen atom and the δ- electronegative atom in another molecule. This attraction gives rise to specific properties observed in substances with hydrogen bonding, such as higher boiling points, surface tension, and unusual solubility characteristics.
In summary, hydrogen bonding occurs because hydrogen forms a partial positive charge when it is covalently bonded to an electronegative atom and can then interact with other electronegative atoms. This unique property of hydrogen makes it the primary element involved in hydrogen bonding.