Chemical Bonding Essentials

Chemical bonding explains how atoms join to form molecules and compounds, influencing their physical properties like melting/boiling points and conductivity. Understanding bond types (ionic, covalent, metallic) and intermolecular forces is key to predicting molecular behavior.

Core Principles

• Electronegativity: Atom's tendency to attract bonding electrons.
• Intramolecular Bonds: Bonds within molecules (covalent).
• Covalent Bond: Sharing of electron pairs.
• Ionic Bond: Transfer of electrons, forming electrostatic attraction.
• Metallic Bond: Attraction between metal ions and delocalized electrons.
• Intermolecular Forces: Attractions between molecules (van der Waals, hydrogen bonds).
• London Forces: Temporary dipoles due to electron movement.
• Dipole-Dipole Forces: Attraction between permanent dipoles in polar molecules.
• Hydrogen Bonds: Special strong dipole-dipole force involving H bonded to N, O, or F.
• Giant Structures: High melting/boiling points due to strong bonds (covalent, ionic, metallic).
• Simple Molecular Structures: Low melting/boiling points due to weak intermolecular forces.
• Electrical Conductivity: Requires mobile charged particles (electrons or ions).

Action Steps

• Determine bond type: Ionic (metal-nonmetal), Covalent (nonmetal-nonmetal), Metallic (metal-metal).
• Assess electronegativity difference for covalent bonds: zero difference = nonpolar, non-zero = polar.
• Identify intermolecular forces present: London forces (all molecules), dipole-dipole (polar molecules), hydrogen bonds (H bonded to N, O, F).
• Relate bond type and intermolecular forces to physical properties: Stronger forces = higher melting/boiling points.
• Determine conductivity: Metals and graphite conduct (mobile electrons); ionic compounds conduct when molten/aqueous (mobile ions).

Key Terms

• Electronegativity: Measure of an atom's tendency to attract a bonding pair of electrons.
• Covalent Bond: Involves sharing of at least one pair of electrons by two atoms.
• Ionic Bonding: Involves electron transfer to form cations and anions, electrostatically attracted.
• Metallic Bonding: Attraction between positive metal kernels and a sea of delocalized electrons.
• Intermolecular Force: Force of attraction between molecules or between atoms of noble gases.
• London Forces: Temporary dipoles attract each other due to uneven electron distribution.
• Dipole-Dipole Forces: Attraction between permanent dipoles in polar molecules.
• Hydrogen Bond: Special case of dipole-dipole force involving H bonded to N, O, or F.