Intermolecular Forces: Flashcards
What are intermolecular bonds?
= forces of attraction between molecules
= weaker than covalent bonds
= can easily be overcomed
What are vanderwall forces?
= electrons in atoms are randomly moving from place to place
= for a fraction of a second more electrons may be on one side more than the other
= temporary dipole
covered in electrons: partial negative
lack of electrons= partial positive
= forms a bond with the other atoms as it repels the other electrons
Are vanderwall forces weak?
= yes + easily broken
= caused by random electron movement
= strength depends on number of electrons
What are dipole dipole forces?
= Only molecules with a permanent dipole can experience this force
= when two molecules with permanent dipoles get close their permanent dipoles create an attraction
= permanent dipole dipole attraction
Why do some molecules have a higher boiling point even though some have a higher polarity?
= may have more electrons
= more electrons means stronger vanderwall force strengths
What are hydrogen bonding?
= formed with elements with highest electronegativity
= flourine nitrogen and oxygen MUST NEED LONE PAIRS
= bonded to a hydrogen
= positive hydrogen atoms are attracted to the lone pair of electrons of the high eletronegative element
What is the strongest type of intermolecular forces?
= hydrogen bonds
What happens if the difference in electronegativity is small?
= cannot cancel out
= overall polarity
Why does water have a high boiling point?
= requires large amounts of energy to break the hydrogen bonds
Why does ice float on water?
= in liquid water the water molecules are moving randomly
= sometimes close sometimes further apart
= hydrogen bonds are constantly being formed and broken
= when cooled they move slowely and when reaching freezing point, they are in an odered structure
= molecules are further apart than liquid water
