BCHEM 153 Lecture Notes Flashcards

Flashcards based on lecture notes covering intermolecular forces, boiling points, and solubility.

Intramolecular forces

The combination of attractive and repulsive electrical forces between pairs of electrons within a molecule

Intermolecular forces

The forces that act between molecules and between molecules and ions. These forces have considerable influence on the physical properties of all substances.

Bond dipole

Separation of electrical charge created when atoms with different EN form a covalent bond

Polar molecule

Vectors of bond dipoles whose sum is greater than zero.

Dispersion (London) forces

Intermolecular force between nonpolar molecules caused by the presence of temporary dipoles in the molecules

Temporary (induced) dipole

Separation of charge produced in an atom or molecule by a momentary uneven distribution of electrons

Polarizability

Relative ease with which the electron cloud in a molecule, ion, or atom can be distorted, inducing a temporary dipole

Dipole–dipole interaction

Attractive force between polar molecules

Hydrogen bond

Strongest dipole–dipole interaction that occurs between H atom bonded to a small, highly electronegative element (F, O, N) and an atom of F, O, or N in another molecule

Sphere of hydration

Cluster of water molecules surrounding an ion in aqueous solution or sphere of solvation if solvent is other than H2O

Ion–dipole interaction

Attractive force between an ion and a molecule that has a permanent dipole

Surface tension

Energy needed to separate the molecules at the surface of a liquid

Viscosity

Measure of resistance to flow of a liquid

Meniscus

Curvature of liquid surface due to adhesive and cohesive forces

Capillary action

The rise of a liquid up a narrow tube due to adhesive forces between the liquid and the tube and cohesive forces within the liquid

Phase diagram

A graphical representation of how the stabilities of the physical states of a substance depend on temperature and pressure

Triple point

Temperature/pressure where all three phases of a substance coexist

Critical point

Specific temperature/pressure at which the liquid and gas phases have the same density

Supercritical fluid

A substance above its critical temperature and pressure

Normal conditions

Occurs at 1 atm.

Critical Point

A combination of temperature and pressure beyond which a gas cannot be liquefied.

Critical Temperature

The temperature beyond which a gas cannot be liquefied regardless of the pressure.

Critical Pressure

The pressure beyond which a liquid cannot be vaporized regardless of the temperature.

Supercritical Fluid

A state of matter beyond the critical point that is neither liquid nor gas.

Solubility

Depending on relative strength of solute–solvent interactions compared to solute–solute or solvent–solvent.

Surface tension

Energy needed to separate the molecules at the surface of a liquid

Viscosity

Measure of resistance to flow of a liquid