Overview
Chemical bonding explains how atoms combine to form compounds. This topic introduces different types of bonds — ionic, covalent, metallic — and how molecular geometry and polarity arise from bonding patterns. Understanding bonding helps predict structure and properties.
Key Concepts and Structures
- Ionic Bonds: Formed by transfer of electrons from metal to nonmetal. High melting points, conduct electricity when molten or dissolved.
- Covalent Bonds: Formed by sharing electrons between nonmetals. Can be polar (unequal sharing) or nonpolar (equal sharing).
- Metallic Bonds: Positive ions surrounded by a “sea” of delocalized electrons. Good conductors, malleable and ductile.
- Bond Polarity: Determined by difference in electronegativity. Greater difference → more polar bond.
- Molecular Polarity: Depends on both bond polarity and shape. Use vector addition of dipoles.
- Lewis Dot Structures: Represent valence electrons. Used to predict shape and bonding.
- VSEPR Theory: Predicts molecular geometry by minimizing electron pair repulsion.
- Linear, bent, trigonal planar, tetrahedral, trigonal bipyramidal, octahedral
- Hybridization: Mixing of orbitals to form equivalent bonding orbitals (sp, sp2, sp3, etc.)
- Bond Types and Strength: Sigma (σ) bonds are stronger and first to form; pi (π) bonds come from side-by-side overlap.
- Resonance: Some molecules can't be represented by a single Lewis structure; real structure is a hybrid of multiple forms.
Quick Tip
Learn to draw accurate Lewis structures and identify electron regions — it makes VSEPR geometry, polarity, and hybridization easier to understand and apply.