A covalent bond is a type of chemical bond formed when two atoms share one or more pairs of electrons to achieve a stable outer electron shell (usually an octet).
- Unlike ionic bonds, where electrons are transferred, in covalent bonds, the electrons are shared.
- Covalent bonds usually occur between non-metal atoms.
- The shared electrons belong to both atoms, creating a stable link.
Types of Covalent Bonds
- Single covalent bond → one pair (2 electrons) shared (e.g., H₂, Cl₂).
- Double covalent bond → two pairs (4 electrons) shared (e.g., O₂, CO₂).
- Triple covalent bond → three pairs (6 electrons) shared (e.g., N₂).
Example:
- In water (H₂O), each hydrogen shares one electron with oxygen, forming two single covalent bonds.
- In oxygen gas (O₂), each oxygen atom shares two electrons, forming a double bond.
Key Features of Covalent Bonds:
- Occur mainly between non-metals.
- Bonds can be polar (unequal sharing, e.g., H₂O) or nonpolar (equal sharing, e.g., O₂).
- Generally form molecules with low melting and boiling points compared to ionic compounds.
- Do not conduct electricity (except in some cases like graphite).