Hydrogen bond is a special type of dipole-dipole attraction. It is a dipole-dipole interaction that occurs between molecules that contain a Hydrogen atom bonded to three of the highest electronegativitys of the periodic table Nitrogen, Oxygen, and Fluorine. Chlorine is also very high, yet since it isn't in the second period of the periodic table it doesn't attract atoms very close to itself since it has a bunch of orbital that get in the way of being able to take an atom and bringing it very close to itself.
- Examples of Hydrogen Bonds are shown in the diagrams below:
Representations:
- Green atoms are Hydrogen atoms
- Orange atoms are Fluorine atoms
- Blue atoms are Oxygen atoms
- Grey atoms are Nitrogen atoms
- Red atoms are Carbon atoms
1.
2.
3.
- A misconception:
A lot of people say that CH3F has Hydrogen bonding. Well that is wrong and below is a diagram and an explanation of why this is wrong.
Above is a diagram of a molecule CH3F, the charges are not important for this explanation. Now to begin, as you can see the Fluorine atom is not attached to any of the Hydrogen atoms so there is no great electronegativity difference between the two. Therefore this molecule even though it has a Hydrogen atom and a Fluorine atom will not have Hydrogen bonding with a similar molecule.
Unlike a molecule CH3OH which is drawn like this.
As you can see in the diagram of a CH3OH molecule above the Oxygen atom is attached to a Hydrogen atom, therefore this molecule can have a Hydrogen bond with another CH3OH molecule.
So just to explain this in a simple, way if the molecule does not have a Hydrogen atom attached to a Nitrogen, Oxygen, or Fluorine atom then it cannot have a Hydrogen bond with a similar molecule.
- More information about Hydrogen Bonding:
- Hydrogen bond is stronger than Dipole-dipole force and therefore stronger than LDF.
