Chemistry Form 4: Chapter 5 - Covalent Bond

Covalent bonds are formed when one or more electron pairs are shared between non-metallic atoms to form a molecule in order to achieve a stable duplet or octet electron arrangements of noble gas.

 How covalent bond is formed in carbon dioxide:

• Atom oxygen has 6 valence electrons and 2.6 electron arrangement.
• Each atom oxygen needs 2 more electrons to fill the valence shell in order to achieve a stable octet electron arrangement. Hence, each atom oxygen contributes 2 electrons for sharing.
• Atom carbon has 4 valence electrons and 2.4 electron arrangement.
• Each atom carbon needs 4 more electrons to fill the valence shell in order to achieve a stable octet electron arrangement. Hence, each atom carbon contributes 4 electrons for sharing.
• One atom carbon shares 4 electrons with two atom oxygen to achieve a stable octet electron arrangement. 

Some examples of covalent bond:

Types of covalent bond: