Intermolecular force (IMF)
An attractive force between molecules (or between ions and molecules), much weaker than the intramolecular (covalent or ionic) bonds within a molecule.
IMFsLondon dispersion force
A temporary, weak attraction caused by momentary, fluctuating electron distributions creating instantaneous dipoles. Present in all molecules; the only IMF in nonpolar molecules. Strength increases with molecular size and surface area (polarizability).
IMFsDipole-dipole force
An attraction between the positive end of one polar molecule and the negative end of a neighboring polar molecule.
IMFsHydrogen bonding
An especially strong type of dipole-dipole force that occurs when hydrogen is bonded to a small, highly electronegative atom (N, O, or F) and attracted to a lone pair on a neighboring N, O, or F.
IMFsPolarizability
A measure of how easily an atom or molecule's electron cloud can be distorted to form a temporary dipole. Larger atoms/molecules with more electrons are more polarizable, leading to stronger London dispersion forces.
IMFsVapor pressure
The pressure exerted by a substance's gas phase in equilibrium with its liquid phase at a given temperature. Weaker IMFs lead to higher vapor pressure (more molecules escape into the gas phase).
States of MatterViscosity
A liquid's resistance to flow. Stronger IMFs between molecules increase viscosity.
States of MatterSurface tension
The energy required to increase a liquid's surface area, caused by IMFs pulling surface molecules inward. Stronger IMFs mean higher surface tension.
States of MatterCrystalline solid
A solid with a highly ordered, repeating particle arrangement. Types include ionic, metallic, covalent network, and molecular solids, each with distinct properties.
SolidsAmorphous solid
A solid lacking a long-range ordered structure (e.g., glass or rubber), resulting in variable, less-defined physical properties compared to crystalline solids.
SolidsCovalent network solid
A solid (like diamond or quartz) held together entirely by covalent bonds extending through the whole structure, giving extremely high melting points and hardness.
SolidsPhase diagram
A graph of pressure versus temperature showing the conditions under which a substance exists as a solid, liquid, or gas, including the triple point and critical point.
States of MatterIdeal gas law
PV = nRT — relates pressure, volume, moles, and temperature of an ideal gas, where R is the gas constant.
Gas LawsKinetic molecular theory (KMT)
A model describing gas particles as point masses in constant random motion with no intermolecular attraction, whose average kinetic energy is directly proportional to absolute temperature.
Gas LawsReal gas deviation
The departure of actual gas behavior from the ideal gas law, most significant at high pressure (molecular volume becomes significant) and low temperature (intermolecular attractions become significant).
Gas LawsPartial pressure / Dalton's law
The pressure a single gas in a mixture would exert if it alone occupied the container. Dalton's law states that total pressure equals the sum of all partial pressures.
Gas LawsSolute / solvent
The solute is the substance being dissolved (present in smaller amount); the solvent is the substance doing the dissolving (present in larger amount).
SolutionsMolarity
A concentration unit defined as moles of solute per liter of solution (mol/L).
Solutions"Like dissolves like"
The general solubility rule that polar/ionic solutes dissolve well in polar solvents, and nonpolar solutes dissolve well in nonpolar solvents, because similar IMFs allow new solute-solvent interactions to replace the ones being broken.
SolubilityChromatography
A separation technique exploiting differences in how strongly mixture components interact with a stationary phase versus a mobile phase.
SeparationElectromagnetic spectrum
The full range of electromagnetic radiation, from low-energy radio waves to high-energy gamma rays, including visible light, infrared, and ultraviolet — each interacting differently with matter.
SpectroscopyBeer-Lambert law
A = εlc — absorbance (A) is directly proportional to molar absorptivity (ε), path length (l), and concentration (c). Used to determine unknown concentrations from absorbance measurements.
Spectroscopy