Hydrogen Bond

The type of intermolecualr force between the Partially positive charge hydrogen amd highly negatively charged Atoms ; like Florine , Nitrogen and rarely Chlorine, is known as Hydrogen bonding or H-bonding.

As Florine and nitrogen are highly electronegative, and this electronegative character enhance the ability to attract the partial positive hydrogen atom and that increases the possibility of H-bonding or hydrogen bonding. 

• Covalent Bond is 20 times more stronger than hydrogen bond. 

Is hydrogen bonding a bond or an inter-molecular force ?

The hydrogen bonding is actually an intermolecular force, Not a bond. It is the force between the molecules of compounds mostly contains hydrogen , florine , nitrogen etc.  And this H-bond is 20 times less stronger than a covalent bond. 

  

Also Read:

 -  Covalent Bond

-   Ionic bond

Hydrogen bonding examples in chemistry :

 

There are numerous compounds which have hydrogen bonding. Most common compounds which have hydrogen bond or H-bond which are listed below in detail; i.e.  H-Bond is present in water molecules , hydrogen bond is present between the molecules of ammonia and also in Hydrogen Floride. 

Hydrogen Bonding in water :

Firstly let’s consider the molecule of a water. As Oxygen is more electronegative element as compared to hydrogen , so water molecule is a polar molecule. So there will be a diapole-diapole attraction between the hydrogen and oxygen. But hydrogen bonding or H-bonding is something more than diapole-diapole attraction. In the figure below hydrogen bond is indicated by a dotted line . 

hydrogen Bonding in NH3: 

 

 The hydrogen of ammonia is resposible for the hydrogen bond. There is a bond between the nitrogen and hydrogen atom this is considered as hydrogen bond. This is shown by dotted line in the picture below

Hydrogen Bonding in HF:

The hydrogen bond present in the molecules of HF hydrogen floride.  This h-bond is indicated by the dotted line in the pic below.

 

Why HF is a weak acid ? 

 

According to the theories, acid is a substance that can give H+ ion. And in HF molecule’s structure H is stuck between Florine and is not easy to give H+ ion for HF molecule thats why HF is said as a weak acid. 

Hydrogen Bonding between chloroform and acetone :

It is not adviseable to limitize the hydrogen bonding to just florine and oxygen, the three atoms in chloroform are responsible fir the Hydrogen or H-bonding with other compounds. There is a hydrogen bonding between hydrogen of chloroform(CHCl3) and acetone(C3H6O). This is shown in the picture below.

Properties of compounds having Hydrogen Bonding:

Thermodynamic properties of covalent hydrides :

     

The boiling point of the hydrates of the group-IV convinces that they have low boiling point as compared to those group V-1,VI-A, VII-A . The reason is that these elements are least electronegative and polarizable.  

why boiling point of H2O is higher than HF ?

 

 Boiling point of the water(H2O) is seems to be more than the HF because water has two covalent bond while HF has only one covalent bond. 

solubility of H-bond molecules :

structure of ice :

Hydrogen bonding in Biological compounds :

Hydrogen bonding is present in the molecules of the living systems. Proteins are the important part of every living organisms. Fibres like those found in Hair, consist of long chain of amino acids. Here's some important Biological compounds that contain hydrogen bonding.

 Hydrogen bonding in DNA:

Deoxryibonucleic acid (DNA) has two spirals chains. These are about to each other on common axis. The give a double helix, This is about 18-20*10^-10 in diameter. They are linked together by H-bonding between their sub units.

 

Hydrogen bonding in food materials : 

  Hydrogen bonding is present in food materials like glucose, fructose, and sucrose. They all have –OH groups in them which are responsible for Hydrogen bonding.

Hydrogen bonding in paints :

One of the most important property of paints and dyes in there is adhesive action. This property is due to hydrogen bonding.