intermolecular forces Flashcards
what are gases?
compressible fluid
what are liquids?
relatively incompressible fluids
what are solids?
nearly incompressible and rigid
what are intermolecular interactions? how do they relate to melting and boiling point?
-molecule-molecule interactions that hold liquids and solids together
-the stronger the interaction, the higher the melting point and boiling point
explain London dispersion forces
-the volumes of atoms and molecules are mostly filled by the electron cloud
-electron clouds are usually spherically symmetric for non-polar molecules
- if they ever become temporarily unsymmetrical, a temporary dipole moment can form for as long as the asymmetry lasts
-the more polarizable the molecule, the more likely this asymmetry will occur
explain trends in polarizability. What do we use to compare polarizability?
-the more electrons a molecule has, the more likely it can become temporarily asymmetric, or polarized
-the larger the size of the molecule, the more polarizable it is
-generally, as we increase the number of electrons and the size of the molecule, the mass also increases
- molar mass
what is an ion-dipole interaction?
interaction between an ion and a molecule with a permanent dipole
what is a dipole-dipole interaction? what trends are seen in dipole-dipole interactions?
-on a polar molecule, the δ- end interacts with the δ+ end
-the larger the dipole, the stronger the interaction
what is hydrogen bonding? what atoms are normally seen in hydrogen bonding?
-strong attractive force that exists between hydrogen atoms bonded to a very electronegative atom and a lone pair of electrons on another small electronegative atom
-most often, F, N, or O, the smallest, most electronegative elements
what is a solution?
homogenous mixture that exists in one phase
what is a colloid? what are the two types?
-heterogenous mixture that exists in more than one phase
-micelle (mixed) and emulsions (separated layers)
what is a solute?
gas (or solid) in a solution of gases (or solids), or the component present in the smaller amount
what is a solvent?
-the liquid in the case of a solution of gases or solids, or the component present in the larger amount
what is a miscible colloid?
fluids than mix with or dissolve in each other in all proportions
what is an immiscible colloid?
fluids that do ot dissolve in each other
what dissolves in water? what is required for this bond to happen?
-water is a polar solvent, so only polar solutes will dissolve in it
-the water-compound attractions must be stronger than the compound-compound and water-water attraction
what does hydrophobic mean?
interaction that repels water, diminishes water solubility
what does hydrophilic mean?
interaction that attracts water, promotes water solubility
what is a phase diagram? what are phases separated by on the diagram?
-graphical way to summarize the conditions under which the various states of a substance are stable
-lines that represent equilibrium between phases
what is the triple point?
point where all three phases are in equilibrium
what is the critical point?
temperature at which the liquid state can no longer exist and the pressure at that temperature
