2.9 Flashcards
(33 cards)
What are intermolecular forces?
Electrostatic forces that cause one molecule to interact with another molecule.
How do intermolecular forces compare to covalent bonds in terms of strength?
Intermolecular forces are much weaker than covalent bonds, with a strength between 0.001 to 15 compared to a strength of about 100 for covalent bonds.
What are the different kinds of intermolecular forces?
- London dispersion forces
- Dipole-dipole forces
- Hydrogen bonding
What are London dispersion forces?
Attractive forces for nonpolar molecules due to momentary and induced dipoles; exist between all molecules.
What affects the strength of London dispersion forces?
The strength is directly related to the number of electrons in the molecule.
What are isoelectronic species?
Atoms, ions, or molecules that have the same number of electrons.
Provide examples of isoelectronic species.
- CO
- CN
- N2
- Si
How does the length of the carbon chain affect London dispersion forces?
The longer the carbon chain, the stronger the London dispersion forces.
What are dipole-dipole forces?
Relatively strong forces of attraction between polar molecules.
What is the significance of dipole-dipole forces in solubility?
They impact the ability of a substance to act as a solvent (‘like dissolves like’).
What are ion-dipole forces?
Forces between ions and a polar molecule.
Give an example of ion-dipole forces.
The interaction between water and NaCl.
What are van der Waals forces?
A combination of many different types of intermolecular forces, including London dispersion, dipole-dipole, and hydrogen bonding.
What type of force is hydrogen bonding?
An exceptionally strong dipole-dipole force.
What is required for hydrogen bonding to occur?
A hydrogen atom must be covalently bonded to a highly electronegative atom, such as N, O, or F.
What property is associated with the attractive forces between molecules in a liquid?
Surface Tension.
What is capillary action?
The ability of a liquid to flow against gravity up a narrow tube.
How do stronger intermolecular forces affect boiling point and melting point?
The stronger the intermolecular forces, the higher the boiling point and melting point of a substance.
What intermolecular forces exist in Cl2?
London Dispersion Forces (LDF).
What intermolecular forces exist in NH3?
Dipole-dipole forces and hydrogen bonding.
Which compound has a higher melting point: Cl2 or NH3?
NH3 has a higher melting point.
What intermolecular forces are present in C8H18?
London Dispersion Forces (LDF).
What intermolecular forces exist in methanol (H3COH)?
Dipole-dipole forces and hydrogen bonding.
What are ionic forces?
Electrostatic forces between metals and non-metals.
