A covalent bond is formed when two non-metal atoms share one or more pairs of electrons, so that each atom achieves a stable electron arrangement.
A covalent bond is formed when two non-metal atoms share one or more pairs of electrons, so that each atom achieves a stable electron arrangement. Malay: ikatan kovalen · Chinese: 共价键.
When two non-metal atoms meet, neither can give up electrons easily, so instead of transferring them they share. Each atom contributes electrons to a shared pair that then counts towards the outer shell of both atoms at once, letting each reach an octet (or a duplet for hydrogen). Atoms can share one, two or three pairs, giving a single, double or triple covalent bond. Because the shared electrons hold only the two bonded atoms together, covalent bonding usually produces separate small molecules rather than a lattice.
Example. In a chlorine molecule, Cl2, each chlorine atom (2.8.7) shares one electron with the other; the shared pair gives each atom eight outer electrons, forming a single covalent bond. In water, H2O, an oxygen atom shares one electron with each of two hydrogen atoms, forming two single bonds. In oxygen, O2, the atoms share two pairs (a double bond), and in nitrogen, N2, they share three pairs (a triple bond).
Confusion to avoid. Do not mix up a covalent bond with an ionic bond. A covalent bond involves shared electrons between non-metals and forms molecules; an ionic bond involves transferred electrons between a metal and a non-metal and forms ions. Also remember that only the shared pairs are bonds, a lone pair is not a bond, even though it is drawn on the same atom.
The covalent bond is the second central bonding type of this chapter, and the weak forces between covalent molecules explain their low melting points, a comparison that appears often in SPM Chemistry.
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