Covalent bonding

Covalent Bonding Overview

• Covalent bonding occurs when two or more non-metal atoms share pairs of electrons
• It’s a major type of chemical bonding which allows atoms to achieve a stable electron configuration
• In this type of bonding, the shared pair of electrons is contributed by each of the bonding atoms, forming a single covalent bond

The Process of Covalent Bonding

• The attractive force in a covalent bond is the electrostatic attraction between the positively charged nuclei and the shared pair of negatively charged electrons
• This process typically occurs between atoms of elements with similar electronegativities
• As both atoms have roughly equal pull on the shared electrons, they effectively share the electrons

Single, Double, and Triple Covalent Bonds

• Single bond: When a pair of electrons is shared, resulting in a bond order of one
• Double bond: When two pairs of electrons are shared, resulting in a bond order of two
• Triple bond: When three pairs of electrons are shared, resulting in a bond order of three
• Note that a double bond is stronger and shorter than a single bond, and a triple bond is stronger and shorter than a double bond

Polarity in Covalent Bonds

• If atoms share the electron pair equally, the bond is a non-polar covalent bond
• If one atom attracts the shared pair more than the other atom, the bond is a polar covalent bond
• The electronegativity difference between the two atoms can help to explain the polarity of a molecule

Shapes of Molecules

• The shape of a covalently bonded molecule can be predicted by its electron pair geometry
• The Valence Shell Electron Pair Repulsion (VSEPR) theory states that electron pairs (both in bonds and lone pairs) will arrange themselves to minimise repulsion
• These shapes can be linear, bent, trigonal planar, trigonal pyramidal, or tetrahedral