Covalent bonds are chemical bonds formed when two atoms share one or more pairs of electrons. This type of bonding usually occurs between non-metal atoms, which have similar tendencies to gain electrons.
By sharing electrons, atoms achieve stable electron configurations, often resembling the noble gas configuration with a full outer shell (commonly 8 electrons—known as the octet rule).
There are different types of covalent bonds:
- Single bond: one pair of electrons shared (e.g., H–H in H₂)
- Double bond: two pairs shared (e.g., O=O in O₂)
- Triple bond: three pairs shared (e.g., N≡N in N₂)
Covalent bonds result in the formation of molecules with definite shapes and lower melting and boiling points compared to ionic compounds. These bonds are fundamental to the structure of organic compounds like DNA, proteins, and water (H₂O), making them essential to life and chemistry.