In a pure covalent bond, two atoms share electrons so that each atom shares one electron from the other atom. Each pair of shared electrons is called a bond pair. In this type of bond, the atoms are held together by the mutual attraction of their nuclei for the shared electron pairs.

Unlike ionic bonds where electrons are clearly transferred from one atom to another, both atoms in a pure covalent bond have an equal share of the electron pair. They are usually only formed when the electronegativity difference between the two atoms is very small.

Some examples of pure covalent bonds are:

* Hydrogen (H-H)

* Chlorine (Cl-Cl)

* Oxygen (O-O)

* Methane (CH4)

* Ethane (C2H6)

These bonds are known for their high strength, as they are held together by the strong electrostatic attraction between the positively charged nuclei and the negatively charged electrons in the bond pair.