Hydrogen Bond

5.4

Hydrogen Bond

Hydrogen bonds attraction forces between hydrogen atom, H that has bonded with an atom of high electronegativity, such as nitrogen, N, oxygen, O or fluorine, F with nitrogen, N, oxygen, O or fluorine, F in another molecule.
For example, water molecule, \(H_2O\) can form hydrogen bonds among water molecules, \(H_2O\).
A water molecule, H\(_2\)O consists of two hydrogen atoms, H and one oxygen atom, O. Hydrogen, H and oxygen, O are bonded by sharing electrons with one another. This type of bond is a covalent bond.
Attraction forces between hydrogen atom, H in water molecule with an oxygen atom, O from another water molecule forms a hydrogen bond

Hydrogen bonds between protein molecules in the hair structure
Formation of hydrogen bond between protein molecule and water molecule
There are protein molecules that form hydrogen bonds among one another in the hair structure.
When hair is wet, protein molecules no longer form hydrogen bonds.
Instead, protein molecules form hydrogen bonds with water molecules, \(H_2O\).
Water molecules, \(H_2O\) will form hydrogen bonds with other hair protein molecules.
This causes hair to stick together.

Compounds in the form of liquids reach the boiling point when the attraction forces between molecules are overcome.
In the covalent compound of ethanol, \(C_2H_5OH\), there are hydrogen bonds formed between molecules, other than weak Van der Waals attraction forces.
Strong hydrogen bonds are difficult to break
More heat energy is required to overcome the weak Van der Waals attraction forces, besides breaking the hydrogen bonds
The boiling point of ethanol,\(C_2H_5OH\) is high. On the other hand, molecules like chlorine, \(Cl_2\) which do not form hydrogen bonds have a lower boiling point compared to ethanol.
Ethanol, \(C_2H_5OH\) is also soluble in water.
The solubility of ethanol, \(C_2H_5OH\) in water is due to the formation of hydrogen bonds between the ethanol molecule, \(C_2H_5OH\) and the water molecule, \(H_2O\).