Weeks 8 & 9 - Intermolecular Forces & Chemical Equilibrium Flashcards
What are intermolecular forces?
Are attractive forces between molecules.
What are dipole-dipole forces?
Attractive forces between the positive end of one polar molecule and the negative end of another polar molecule.
The larger the dipole moment, the greater the force
What are dipole-induced dipole forces?
A molecule with a permanent dipole induces a dipole in a neighbouring molecule.
What is an ion-dipole force?
An attractive force that results from the electrostatic attraction between an ion and a neutral molecule that has a dipole.
Cation attracts partially negative end of neutral polar molecule.
Anion attracts partially positive end of neutral polar molecule.
What is the definition of polarizability?
How easily the electron distribution in the molecule or atom can be distorted.
Explain the Van der Waals forces.
Are the residual attractive or repulsive forces between molecules or atomic groups that do not arise from a covalent bond, or electrostatic attraction of ions or of ionic groups with one another or with neutral molecules.
Forces can be attractive or repulsive.
What is a dispersion force?
A force between molecules or atoms, arising from a brief shift of orbital electrons to one side of the atom or molecule resulting of a temporary dipole induced in atoms or molecules
What occurs in hydrogen bonds?
A special dipole-dipole interaction between the hydrogen atoms in a polar bond, (H-FON), and the lone pair of an electronegative O, N or F atom
What is fluid surface tension?
The elastic force in the surface, results from the greater attraction of liquid molecules to each other (cohesion).
Strong intermolecular forces = high surface tension.
What is cohesion?
Is the intermolecular attraction between like molecules.
What is adhesion?
Is an attraction between unlike molecules
What is viscosity?
A measure of a resistance to flow- high intermolecular forces= high viscosity.
Bonds between molecules must be broken to allow molecules to move past each other
What is a metallic bond?
Arises from the electrostatic force between conduction electrons and positively charged metal ions
What is a phase change?
A physical change as a result of changes in molecular order. Usually heat or energy transfer
What is the phase change from liquid to gas?
Vaporisation
What is the phase change from gas to liquid?
Condensation
What is the phase change from liquid to solid?
Freezing.
What is the phase change from solid to liquid?
Melting.
What is the phase change from solid to gas?
Sublimation
What is the phase change from gas to solid?
Deposition
What is equilibrium liquid vapour pressure?
The pressure exerted by a vapour in equilibrium with its condensed phases at a given temp (at equilibrium with the atmosphere outside it)
What is liquid vapour pressure?
The pressure exhibited by vapour above a liquid surface.
Describe condensation.
As the concentration of molecules in the vapour phase increases, some molecules condense and return to the liquid phase.
Occurs when molecules collide with the surface of the liquid and become trapped by intermolecular forces.
What is a dynamic equilibrium?
Exists once a reversible reaction ceases to change its ratio of reactants/ products, but substances move between the chemicals at an equal rate, there is no net change
