Dispersion forces

• Ionic compounds have strong electrostatic attractions between oppositely charged ions, resulting in high melting points and boiling points.
• Intermolecular forces are responsible for the physical properties of matter, such as boiling point, melting point, viscosity, surface tension, density, and solubility.
• The strength of the intermolecular force is directly proportional to the number of electrons on an atom.
• Atoms with more electrons will experience stronger dispersion forces than atoms with fewer electrons.
• Covalent molecules with polar bonds can form hydrogen bonds due to the partial positive charge on H atoms and the partial negative charge on F or O atoms.
• The strength of intermolecular forces depends on the type of bonding present (ionic or covalent) and the polarity of the molecule.
• Hydrogen bonding is stronger than dipole-dipole interactions but weaker than ionic bonding.
• Dispersion forces can be described by London's equation, which states that the energy required to separate two molecules is equal to half the product of their polarizability times the square of the frequency factor.
• Melting and boiling points increase with increasing molecular weight because larger molecules require more energy to overcome their intermolecular forces.
• Hydrogen bonding occurs when there is a large difference in electronegativity between two atoms (F-H and O-H).
• Dispersion forces can be described using London's equation, which states that the energy required to separate two molecules by a distance r is given by E = A/r^6.
• The strength of intermolecular forces depends on factors such as polarity, size, shape, and arrangement of molecules.
• Boiling point is the temperature at which a liquid changes to a gas state.
• London's equation predicts that larger molecules will have higher dispersion energies due to increased electron cloud distortion.
• Larger molecules also have higher densities due to closer packing of particles.
• Water has very strong cohesive forces due to its ability to form hydrogen bonds.
• London's equation predicts that the energy required to separate two molecules decreases rapidly as they move further apart.
• London's equation predicts that larger molecules have higher boiling points because they require more energy to overcome the dispersion forces between them.
• Ionic compounds have strong electrostatic attractions between oppositely charged ions.
• Ionic compounds have strong electrostatic attractions between oppositely charged ions, while covalently bonded substances have weak dispersion forces.