Chemical Bonding: Ionic and Covalent Bonds

Chemical Bonding

Ionic Bonding

• Definition: A type of chemical bond formed through the electrostatic attraction between oppositely charged ions.
• Formation:
  • Typically occurs between metals (which lose electrons) and nonmetals (which gain electrons).
  • Example: Sodium (Na) donates an electron to Chlorine (Cl), forming Na⁺ and Cl⁻ ions.
• Characteristics:
  • High melting and boiling points.
  • Generally soluble in water.
  • Conduct electricity when dissolved in water or molten.

Polar and Nonpolar Bonds

• Covalent Bonds: Formed by the sharing of electron pairs between atoms.
• Nonpolar Covalent Bond:
  • Electrons are shared equally.
  • Occurs between identical atoms (e.g., H₂, O₂) or atoms with similar electronegativities.
• Polar Covalent Bond:
  • Unequal sharing of electrons due to differences in electronegativity.
  • Results in a dipole moment where one end of the bond is slightly negative and the other slightly positive (e.g., H₂O).
• Electronegativity Scale:
  • The difference in electronegativity determines bond type:
    • 0 - 0.4: Nonpolar
    • 0.5 - 1.7: Polar

    • 1.7: Ionic (more than 50% ionic character).

Metallic Bonding

• Definition: A type of bonding found in metals where electrons are delocalized and shared among a lattice of positively charged ions.
• Characteristics:
  • High electrical and thermal conductivity.
  • Malleability and ductility due to the ability of metal atoms to slide over one another.
  • Luster due to the ability to reflect light.

Bonding Theories

• VSEPR (Valence Shell Electron Pair Repulsion):

  • Predicts the geometry of molecules based on the repulsion between electron pairs in the valence shell.
  • Key shapes include linear, trigonal planar, tetrahedral, bent, and octahedral.
  • Lone pairs exert more repulsion than bonding pairs, affecting molecular shapes.

• Hybridization:

  • The concept where atomic orbitals mix to form new hybrid orbitals for bonding.
  • Types include:
    • sp: Linear geometry (180°)
    • sp²: Trigonal planar (120°)
    • sp³: Tetrahedral (109.5°)
    • sp³d: Trigonal bipyramidal (90° and 120°)
    • sp³d²: Octahedral (90°)

Covalent Bonding

• Definition: Chemical bonding resulting from the sharing of electron pairs between atoms.
• Types:
  • Single bond: One pair of shared electrons (e.g., H-H).
  • Double bond: Two pairs of shared electrons (e.g., O=O).
  • Triple bond: Three pairs of shared electrons (e.g., N≡N).
• Properties:
  • Variable melting and boiling points.
  • Poor conductivity in solid and liquid states.
  • Generally insoluble in water but soluble in organic solvents.

Ionic Bonding

• A type of chemical bond formed through the electrostatic attraction between oppositely charged ions.
• Typically occurs between metals (which lose electrons) and nonmetals (which gain electrons).
• Example: Sodium (Na) donates an electron to Chlorine (Cl), forming Na⁺ and Cl⁻ ions.
• High melting and boiling points.
• Generally soluble in water.
• Conduct electricity when dissolved in water or molten.

Polar and Nonpolar Bonds

• Covalent Bonds: Formed by the sharing of electron pairs between atoms.
• Nonpolar Covalent Bond:
  • Electrons are shared equally.
  • Occurs between identical atoms (e.g., H₂, O₂) or atoms with similar electronegativities.
• Polar Covalent Bond:
  • Unequal sharing of electrons due to differences in electronegativity.
  • Results in a dipole moment where one end of the bond is slightly negative and the other slightly positive (e.g., H₂O).
• Electronegativity Scale:
  • The difference in electronegativity determines bond type:
    • 0 - 0.4: Nonpolar
    • 0.5 - 1.7: Polar

    • 1.7: Ionic (more than 50% ionic character).

Metallic Bonding

• A type of bonding found in metals where electrons are delocalized and shared among a lattice of positively charged ions.
• High electrical and thermal conductivity.
• Malleability and ductility due to the ability of metal atoms to slide over one another.
• Luster due to the ability to reflect light.

Bonding Theories

• VSEPR (Valence Shell Electron Pair Repulsion):
  • Predicts the geometry of molecules based on the repulsion between electron pairs in the valence shell.
  • Key shapes include linear, trigonal planar, tetrahedral, bent, and octahedral.
  • Lone pairs exert more repulsion than bonding pairs, affecting molecular shapes.
• Hybridization:
  • The concept where atomic orbitals mix to form new hybrid orbitals for bonding.
  • Types include:
    • sp: Linear geometry (180°)
    • sp²: Trigonal planar (120°)
    • sp³: Tetrahedral (109.5°)
    • sp³d: Trigonal bipyramidal (90° and 120°)
    • sp³d²: Octahedral (90°)

Covalent Bonding

• Chemical bonding resulting from the sharing of electron pairs between atoms.
• Types:
  • Single bond: One pair of shared electrons (e.g., H-H).
  • Double bond: Two pairs of shared electrons (e.g., O=O).
  • Triple bond: Three pairs of shared electrons (e.g., N≡N).
• Properties:
  • Variable melting and boiling points.
  • Poor conductivity in solid and liquid states.
  • Generally insoluble in water but soluble in organic solvents.