Intermolecular forces

• The presence of hydrogen bonding in a substance can significantly increase its boiling point compared to substances with only dipole-dipole forces or London dispersion forces.
• Cations polarize, Anions are polarizable
• Ionic compounds have high melting points due to strong electrostatic attractions between oppositely charged ions.
• In ionic compounds, the cation is surrounded by anions and vice versa.
• Metallic bonds hold metal atoms together through the sharing of delocalized electrons among all the atoms in the lattice structure.
• London dispersion forces are the only intermolecular forces in between noble gas atoms and non-polar molecules
• Dipole-dipole interactions occur when two polar molecules interact with one another.
• The strength of London dispersion forces increases with increasing molecular mass.
• Melting point decreases down group 17 because there is less attraction between particles (weaker London dispersion forces).
• Intermolecular forces can be classified into three categories based on their strengths: weak (van der Waals), moderate (hydrogen bonding), and strong (ionic).
• Hydrocarbons have lower boiling points than hydrogen halides due to differences in intermolecular forces.
• Weak intermolecular forces include dipole-dipole interactions, London dispersion forces, and hydrogen bonding.
• Boiling points increase across period 3 due to increased number of electrons available for bonding and stronger London dispersion forces.
• Ionic compounds have the strongest intermolecular forces and high melting/boiling points.
• Increasing atomic number leads to stronger ionic bonds and higher melting/boiling points.
• Dipole-dipole attractions occur when two polar molecules interact with one another.
• The more electronegative the molecules, the more polar the bond.
• The greater the electronegativity difference, the more polar is the bond.