Intermolecular forces Flashcards
what are intrAmolecular forces?
Intramolecular forces are forces within a molecule and are usually covalent bonds (formed when 2 atoms share electrons)
what are intERmolecular forces?
forces between the molecules (weaker than intrAmolecular forces)
are intrAmolecular or intERmolecular forces weaker?
intERmolecular
what are the three types of intermolecular forces?
-London dispersion forces
-permanent dipole dipole forces
-hydrogen bonding
what are London dispersion forces between?
between all molecules, but the only intermolecular force between non-polar molecules
what cause a London dispersion force?
at any instant, electron density in molecules is uneven, causing an instantaneous dipole
what is the effect of an instantaneous dipole?
the instantaneous dipole causes an induced dipole in a neighbouring molecule
what is the effect of more electrons on London dispersion forces?
more electrons=stronger induced dipoles=stronger IMFs
what a permanent dipole-permanent dipole forces between?
polar molecules (have permanent dipole)
how do permanent dipole-permanent dipole forces attract?
opposite ends of neighbouring dipoles attract each other
bigger the permanent dipole (difference in electronegativity)…
stronger the IMF
what is hydrogen bonding?
special type of permanent dipole-permanent dipole IMF
what does hydrogen bonding occur between?
polar molecules which have a hydrogen atom bonded DIRECTLY to NOF
how does hydrogen bonding attract?
lone pair of NOF attracted to H (delta positive)of neighbouring molecule
what is the relative strength of the three IMF?
hydrogen bond>permanent-dipole permanent-dipole>London dispersion forces
