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Intermolecular forces

Forces of attraction or repulsion between neighboring molecules.

Intramolecular forces

Forces that occur within a molecule, such as covalent or ionic bonds.

Van der Waals forces

Weak intermolecular forces that include dipole-dipole interactions, dispersion forces, and hydrogen bonds.

Hydrogen bonding

A special type of dipole-dipole interaction that occurs when hydrogen is bonded to highly electronegative atoms like N, O, or F.

Dipole-dipole forces

Attractive forces that occur between polar molecules, caused by the positive end of one molecule being attracted to the negative end of another.

London dispersion forces

Weak intermolecular forces resulting from temporary dipoles in atoms and molecules.

Cohesive forces

Intermolecular forces that bind like molecules to one another, such as hydrogen bonding in water.

Adhesive forces

Intermolecular forces that bind a substance to a surface.

Boiling point

The temperature at which the vapor pressure of a liquid equals the external pressure surrounding the liquid.

Melting point

The temperature at which a solid becomes a liquid.

Phase changes

Transformations between different states of matter, such as solid, liquid, and gas.

Critical temperature

The highest temperature at which a gas can be condensed to a liquid at any applied pressure.

Vapor pressure

The pressure exerted by a vapor in equilibrium with its liquid in a closed system.

Viscosity

A measure of a liquid's resistance to flow.

Surface tension

The inward forces that must be overcome to expand the surface area of a liquid.

Sublimation

The process in which a solid changes directly into gas without becoming a liquid.

Dynamic equilibrium

A state of balance in which two opposing processes occur at equal rates; for example, in vaporization and condensation.

Ion-dipole forces

Forces that occur between an ion and the partial charge on the end of a polar molecule.

Molecular solids

Solids composed of molecules held together by intermolecular forces.

Covalent network solids

Solids that consist of a network of covalent bonds extending throughout the material.

Ionic solids

Solids that consist of cations and anions held together by ionic bonds.

Metallic solids

Solids in which metal atoms contribute their delocalized electrons to a shared sea.

Temperature

A measure of the average kinetic energy of the particles in a substance.

Heat

The energy transferred between substances from a region of higher temperature to a region of lower temperature.

Phase diagram

A graphical representation showing the phases of a substance at various temperatures and pressures.

Melting

The process in which a solid turns into a liquid as it absorbs heat.

Freezing point

The temperature at which a liquid becomes a solid.

Condensation

The process by which a gas turns into a liquid.

Evaporation

The process of a liquid changing into a gas, typically at temperatures below the boiling point.

Triple point

The unique set of conditions at which all three phases (solid, liquid, gas) of a substance coexist in equilibrium.

Latent heat

The amount of heat energy absorbed or released during a phase change without a change in temperature.

Supercooling

The process of lowering the temperature of a liquid below its freezing point without it becoming solid.

Solubility

The ability of a substance to dissolve in a solvent.

Solvent

A substance that dissolves a solute, resulting in a solution.

Solute

The substance that is dissolved in a solvent to form a solution.

Concentration

The amount of solute present in a given volume of solution.

Molecular weight

The sum of the atomic weights of all atoms in a molecule.

Chemical bond

A lasting attraction between atoms that enables the formation of chemical compounds.

Electronegativity

The tendency of an atom to attract electrons in a chemical bond.

Atomic radius

The distance from the nucleus of an atom to the outermost electrons.

Ionization energy

The energy required to remove an electron from an atom in the gas phase.

Thermal conductivity

The ability of a substance to conduct heat.

Specific heat capacity

The amount of heat required to change the temperature of a unit mass of a substance by one degree Celsius.

Dissociation

The process by which an ionic compound separates into its individual ions in solution.

Oxidation state

The hypothetical charge an atom would have if all bond electrons were assigned to the more electronegative atom.

pH

A measure of the acidity or alkalinity of a solution on a scale from 0 to 14.

Buffer solution

A solution that resists changes in pH when small amounts of acid or base are added.

Kinetic molecular theory

A theory that explains the behavior of gases in terms of particles in motion.

Diffusion

The process by which particles spread from areas of high concentration to areas of low concentration.

Osmosis

The diffusion of water across a semipermeable membrane.

Phase transition

The transformation of a substance from one phase to another, such as from solid to liquid.

Crystalline solid

A solid that has a well-ordered structure, with a repeating pattern of atoms.

Amorphous solid

A solid that lacks a well-defined structure and does not have a uniform arrangement of atoms.

Thermal equilibrium

A state in which two bodies in contact do not exchange heat, as they are at the same temperature.

Molarity

The concentration of a solution expressed as the number of moles of solute per liter of solution.

Colligative properties

Properties that depend on the number of solute particles in a solution, not their identity.

Solvent-solute interactions

Interactions that occur between the solute and solvent molecules in a solution, which affect solubility.

Raoult's Law

States that the vapor pressure of a solvent is directly proportional to the mole fraction of solvent in the solution.

Henry's Law

States that the amount of gas that dissolves in a liquid is proportional to the partial pressure of that gas above the liquid.

Le Chatelier's Principle

States that if an external change is applied to a system at equilibrium, the system will adjust to counteract that change.

Equilibrium constant (K)

The ratio of the concentrations of products to reactants at equilibrium, each raised to the power of their coefficients.

Endothermic reaction

A reaction that absorbs heat from the surroundings.

Exothermic reaction

A reaction that releases heat to the surroundings.

Transition state

A high-energy state in a reaction pathway that occurs during the transformation of reactants to products.

Reaction rate

The speed at which reactants are converted to products in a chemical reaction.

Catalyst

A substance that increases the rate of a reaction without being consumed in the process.

Activation energy

The minimum energy required to start a chemical reaction.

Saturation point

The point at which a solution can no longer dissolve any more solute at a given temperature.

Buffer capacity

The ability of a buffer solution to resist changes in pH when small amounts of acid or base are added.

Titration

A technique used to determine the concentration of a solute in a solution by reacting it with a standard solution.

Electrolyte

A substance that dissociates into ions when dissolved in water, conducting electricity.

Hydration energy

The energy released when ions or molecules are surrounded by water molecules.

Oxidation-reduction (redox) reaction

A reaction involving the transfer of electrons between two species.

Half-life

The time required for half of the reactants in a chemical reaction to be consumed.

Photochemistry

The branch of chemistry that deals with the effects of light on chemical reactions.

Chemical equilibrium

A state in which both reactants and products are present in concentrations that have no further tendency to change.

Spectrophotometry

A method used to measure the amount of light absorbed by a solution.

Ionic dissociation

The process by which an ionic compound separates into its constituent ions in solution.

Thermodynamics

The study of energy, heat, and their transformations.

Phase equilibrium

A state in which the phases of a substance coexist without net changes in mass or energy.

Polarity

The distribution of electrical charge over the atoms joined by the bond.

Isotopes

Atoms of the same element that have the same number of protons but different numbers of neutrons.

Nucleation

The initial step in the formation of a new phase, such as a liquid forming from a vapor.

Saturation vapor pressure

The pressure exerted by a vapor in thermodynamic equilibrium with its condensed phases at a given temperature.

Superheated vapor

A vapor that is heated above its boiling point without becoming a liquid.

Capillarity

The ability of a liquid to flow in narrow spaces without the assistance of external forces.

Electrolytic dissociation

The process by which an ionic compound separates into its ions in a solution and conducts electricity.

Heat of fusion

The amount of heat required to change a substance from solid to liquid at its melting point.

Heat of vaporization

The amount of heat required to convert a unit mass of a liquid into vapor without a temperature change.

Conducivity

The ability of a substance to conduct electric current.

Thermal expansion

The increase in volume or length of a substance as its temperature rises.

Hydrolysis

The chemical reaction involving water that breaks down compounds.

Preparative chemistry

The branch of chemistry focused on the preparation of chemical compounds.

Chemical synesis

The process of combining simpler substances to form more complex compounds.

Gas law

Rules that describe the behavior of gases in relation to pressure, volume, and temperature.

Crystallization

The process of forming solid crystals from a homogeneous solution.

Anomaly of water

The unusual properties of water, including its high specific heat and solid-state density.

Amphipathic molecule

A molecule that has both a hydrophobic and a hydrophilic part.

Metastability

A state that is stable under some conditions but not under others.

Chemical kinetics

The study of reaction rates and the factors that affect them.