Condensed phases: the liquid and solid phases; phases in which particles interact strongly.
13.1
Gas condensed when cooled and compressed.
In the liquid state the forces of attraction among particles are great enough that disordered clustering occurs.
It is hard to compress a liquid.
Liquids diffuse into other liquids with which they are misicible.
The natural diffusion rate is slow at normal temperatures.
Cooling a liquid lowers its molecular kinetic energy.
Solidification
Crystallization
Solids are incompressible and are very dense relative to gases.
13.2
Intermolecular forces: the forces between individual particles of a substance.
Intramolecular forces: covalent and ionic bond within compounds.
Attractive forces between molecules are mainly due to hydrogen bonding.
Ion-ion attraction
The energy of attraction between two oppositely charged ions is directly proportional to the charges on the ions and inversely proportional to the distance of separation.
Ionic compound has high melting points.
The product q+ q- increases as the charges on ions increase.
Ionic substances containing multiply charged ions usually have higher melting and boiling points than ionic compound containing only singly charged ions.
For a series of ions of similar charges, the closer approach of smaller ions results in stronger interionic attractive force and higher melting points.
Dipole-dipole interactions
Permanent dipole-dipole interactions occur between polar covalent molecules because of the traction of theatoms of one molecule to the atoms of another molecule.
Dipole-dipole interaction become less important as temperature increases.
Hydrogen bonding: very strong dipole-dipole interaction
Strong hydrogen bonding occurs among polar covalent molecules containing H and one of the three small, highly electronegative elements—F, O, or N.
The molecule contains the hydrogen bonding atom is often referred to as the hydrogen-bond