IMFs Flashcards
What are intermolecular forces?
The attractions between molecules are not nearly as strong as the intermolecular attractions that hold compounds together; these intermolecular attractions are, however, strong enough to control physical properties, such as boiling and melting points, vapor pressures, and viscosities; referred to as van der Waals forces
What’s the importance of states of matter in bonding?
The fundamental difference between states of matter is the distance between particles.
What are the three van der Waals forces?
dipole-dipole interactions
hydrogen bonding
London dispersion forces
What are london dispersion forces?
attractions between an instantaneous dipole and an induced dipole
What are the characteristics of dispersion forces?
Weak, short lived
exerted by non polar molecules
Electrons are not evenly distributed at all times (instantaneous dipole)
Lasts longer at low temperature
Eventually long enough to make liquidsMore electrons, more polarizable
Bigger molecules, higher melting and boiling points
What are Dipole-dipole interactions?
molecules that are permanent dipoles are attracted to each other
What’s Hydrogen Bonding?
The dipole-dipole interactions experienced when Hydrogen is bonded to Nitrogen, Oxygen, or F are unusually strong.
What’s viscosity?
resistance of a liquid to flow
What are the physical properties of strong IMFs
High melting/freezing point
High boiling point
Low Vapor pressure
Define heat of fusion
the energy required to change a solid at its melting point to a liquid
Define heat of vaporization
the energy required to change a liquid at its boiling point to a gas
Define the heat of sublimation
energy required to change a solid directly to a gas
define boiling point
the temperature at which its vapor pressure equls atmospheric pressure
define normal boiling point
the temperature at which its vapor pressure is at 760 torr or 1 atm
define solutions
homogenous mixtures of two or more pure substances
