Covalent Bonds Overview

Covalent Bonds

• A covalent bond forms when two atoms share electron pairs.
• This sharing usually completes electron shells, leading to stability.
• Covalent bonds commonly occur between nonmetals with similar electronegativities.

Types of Covalent Bonds

• Single Covalent Bond: Shares one pair of electrons. Example: H₂
• Double Covalent Bond: Shares two pairs of electrons. Example: O₂, CO₂
• Triple Covalent Bond: Shares three pairs of electrons. Example: N₂, C₂H₂ (ethyne)
• Polar Covalent Bond: Unequal electron sharing due to electronegativity differences. Example: H₂O, HCl
• Nonpolar Covalent Bond: Equal electron sharing due to similar electronegativity. Example: Cl₂, CH₄

General Characteristics of Covalent Bonds

• Formation: Formed by sharing electron pairs.
• Strength: Strong due to electrostatic attraction between nuclei and shared electrons.
• Physical State: Often gases, liquids, or soft solids at room temperature.

Properties of Covalent Compounds

• Melting and Boiling Points: Generally lower than ionic compounds.
• Solubility: Polar compounds dissolve in polar solvents (e.g., water); nonpolar compounds dissolve in nonpolar solvents (e.g., benzene).
• Electrical Conductivity: Do not conduct electricity because they lack free-moving ions or electrons.
• Molecular Nature: Form discrete molecules unlike ionic crystal lattices.

Directional Characteristics of Covalent Bonds

• Specific Orientation: Directional due to localized shared electron pairs.

• Molecular Geometry: Shapes determined by the arrangement of atoms (e.g., linear, bent, tetrahedral, trigonal planar).

• Bond Angles: Angles between bonds are determined by electron pair repulsion (VSEPR theory).

• Orbital Overlap: Bonds form through overlap of atomic orbitals influencing molecule shapes.

• Covalent bonds are crucial for organic and inorganic molecules due to their stability and directionality.