Chemical Bonding Overview

Study Notes

Weakest intermolecular forces influencing physical properties.
Non-directional and non-valence forces, acting independently among molecules.
Exist in solid, liquid, or gaseous states without covalent, ionic, or metallic bonds.
Inert gases may exist in various states due to intermolecular forces.

Dipole-Dipole Interaction: Attraction between oppositely charged poles of polar molecules (e.g., H2S, HCl).
- Arrangements:
  - Head to Tail (in gas): E ∝ 1/r⁶
  - Anti-parallel (in solid/liquid): E ∝ 1/r³
- Anti-parallel is favored under low thermal agitation and for smaller molecules.
Dipole-Induced Dipole Interaction: Attraction between polar and non-polar molecules (e.g., Cl2 and H2O).
- Interaction strength increases with larger non-polar molecules.
Instantaneous Dipole-Induced Dipole Interaction: Also known as London forces; weak forces in non-polar molecules at low temperatures (e.g., F2, Cl2).
- Present in both polar and non-polar species, stronger in non-polar.
- Strength depends on size, molecular mass, and polarizability of electrons.

Ion-Dipole Interaction: Attraction of polar molecules to ions, with cations attracting negative dipoles and anions attracting positive dipoles.
Ion-Induced Dipole Interaction: Non-polar molecules polarize in contact with ions, leading to attraction (e.g., Na+ with Cl2).
- Attraction strength increases with non-polar molecule size.

Boiling point is influenced by molecular mass and the strength of intermolecular interactions.

Lone pairs prefer hybrid orbitals with greater s-character.
More electronegative atoms/groups prefer hybrid orbitals with lower s-character.

Applies to:
- Central atom from the third period or lower in the periodic table.
- At least one lone pair present on the central atom.
- Surrounding atom's electronegativity < 2.5.
Aligns experimental bond angles with theoretical predictions in specific molecular scenarios.