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IMF
Intermolecular Forces
Question | Answer |
---|---|
Intermolecular Forces | forces between seperate molecules, WEAKLY hold together two different |
Intramolecular Forces | ionic and covalent bonds, they are STRONG and hold compounds and molecules together |
intra | inside |
inter | in-between |
What do we mainly use intermolecular forces for? | covalent not as much for ionic |
Phase Changes | when a substance changes from solid to liquid to gas, the molecules remain intact |
What are the changes in state due to? | changes in the forces among molecules rather than in those within the molecules |
How many intermolecular forces are there? | 4, but right now were only leaning three |
Types Of Intermolecular Forces | hydrogen bonding, dipole-dipole, London dispersion |
What does every polar molecule have? | a dipole |
Hydrogen Bond | 1. bound to a highly electronegative atom N,O, and F 2. special dipole-dipole interaction which is the strongest IMF |
Dipole-Dipole | 1. interactions between two polar molecules 2. polar molecules line up so that the positive and negative ends are close to each other |
London Dispersion (van der Waals Forces) | 1. occurs in ALL molecules 2. higher molar mass, more electrons, more polarizable, stronger LDF 3. attractive forces created by the motion of electrons making temporary dipoles induced in atoms or molecules |
What is dipole induced significant in? | large atoms/molecules, strength increases with mass of the molecule |
What does a stronger IMF mean? | 1. higher melting and boiling point 2. higher viscosity 3. higher surface tension 4. less volatile( evaporates less easily) |
Surface Tension | the amount of energy required to stretch or increase the surface of a liquid by a unit area |
Cohesion | the intermolecular attraction between LIKE molecules |
Adhesion | an attraction between UNLIKE molecules |
Viscosity | a measure of a fluid's resistance to flow |
How can you tell if a molecule is polar? | contain polar bonds that contain form dipoles, look at the electronegativity of the bond, if the difference in electronegativities is between 0.4 and 1.7 then it is polar |
Why are the properties of molecular compounds so diverse? | the strengths of intermolecular attractions vary widely |
How do dispersion forces compare to dipole interactions? | both involve an electrical attraction between molecules, but dispersion forces are much weaker and temporary |
What is thought to cause the dispersion forces? | motion of electrons |
What causes dipole interactions? | attraction between polar molecules |
What causes hydrogen bonding? | bonding of a covalently bonded hydrogen atom with an unshared electron pair |
A hydroxide group (-OH) is a component of most | bases |