what is H-bond? why only N2OF form H-bond.Explain types of H-bond with examples
Answers
Answer:
A hydrogen bond is a partial intermolecular bonding interaction between a lone pair on an electron rich donor atom, particularly the second-row elements nitrogen, oxygen, or fluorine, and the antibonding molecular orbital of a bond between hydrogen and a more electronegative atom or group.......In Water oxygen atom has two lone pairs and two hydrogen atoms, meaning that the total number of hydrogen bonds of a water molecule is up to four.
In HF, each molecule has one δ+ hydrogen and three active lone pairs. In the liquid as a whole, there are therefore three times as many lone pairs are there are δ+ hydrogens. On average, then, each molecule can only form one hydrogen bond using its δ+ hydrogen and one involving one of its lone pairs. The other lone pairs are essentially wasted. Each ammonia molecule can form one hydrogen bond using its lone pair and one involving one of its δ+ hydrogens. The other hydrogens are wasted.
Hydrogen bond
A Hydrogen Bond is an electromagnetic attraction between polar molecules in which hydrogen atom (H) is bound to a larger atom, such as oxygen (O), nitrogen (N) or fluorine (F). This is an attraction between positive and negative poles of the charged atoms.
What are the Conditions for Hydrogen Bonding?
In a molecule, when a hydrogen atom is linked to a highly electronegative atom, it attracts the shared pair of electrons more and so this end of the molecules becomes slightly negative while the other end becomes slightly positive.
Examples of Hydrogen Bonding
Hydrogen Bonding in Hydrogen fluoride
Fluorine having the highest value of electronegativity forms the strongest hydrogen bond.
Hydrogen Bonding in Water
A water molecule contains a highly electronegative oxygen atom linked to the hydrogen atom.
why only N2,O,F form H-bond ?
Because of the difference in electronegativity, the H atom bears a large partial positive charge and the N, O or F atom bears a large partial negative charge.
Types of Hydrogen Bonding
There are two types of H bonds, and it is classified as the following:
- Intermolecular Hydrogen Bonding
- Intramolecular Hydrogen Bonding
Intermolecular Hydrogen Bonding
When hydrogen bonding takes place between different molecules of the same or different compounds, it is called intermolecular hydrogen bonding.
For example – hydrogen bonding in water, alcohol, ammonia etc.
Intramolecular Hydrogen Bonding
The hydrogen bonding which takes place within a molecule itself is called intramolecular hydrogen bonding.