Covalent Bonding Overview

  • Covalent Bonds

    • Formed between two non-metals
    • Involves sharing of electrons between nuclei
    • Stability achieved by overlapping atomic orbitals
    • Represented by a line (e.g., H-H for hydrogen)

  • Lewis Formulas

    • Simplified diagrams representing electron pairs
    • Example: chloride can be shown with dots/crosses
    • Steps to draw: count valence electrons, skeletal structure, add electron pairs

  • Multiple Bonds

    • Types: Single (2 electrons), Double (4 electrons), Triple (6 electrons)
    • Stronger and shorter than single bonds; triple bonds are shortest

  • Coordinate Bonds

    • Formed when one atom donates a lone pair to an electron-deficient atom
    • Example: Ammonium ion (NH4+)

  • Shapes of Molecules (VSEPR)

    • Predicts shapes based on electron pairs:
    • Linear: 2 electron domains (180°)
    • Trigonal Planar: 3 domains (120°)
    • Tetrahedral: 4 domains (109.5°)
    • Shapes adjust for lone pairs due to stronger repulsion

  • Bond Polarity

    • Electronegativity: ability of an atom to attract electrons
    • Polar bonds form when there is a difference in electronegativity
    • Dipole moment indicates the direction of polarity

  • Molecular Polarity

    • Overall polarity depends on molecular geometry
    • Polar bonds can cancel out if symmetrical

  • Giant Covalent Structures

    • Form extensive networks (examples: diamond, graphite)
    • Extremely high melting/boiling points due to strong covalent bonds

  • Intermolecular Forces

    • Types: London dispersion, dipole-dipole, hydrogen bonding
    • Stronger forces result in higher boiling points

  • Hydrogen Bonding

    • Strongest intermolecular force; occurs when H is bonded to O, N, or F

  • Chromatography

    • Separation technique using stationary and mobile phases
    • Rf value calculated to measure separations of components

  • Hybridisation

    • Mixing of atomic orbitals to form hybrid orbitals (sp, sp2, sp3)
    • Determines bond formation and geometry based on electrons present

  • Formal Charge

    • Useful for identifying the most stable Lewis structure
    • Calculated based on valence, bonding, and non-bonding electrons.