Kinetic Molecular Theory and Intermolecular Forces

Vocabulary practice flashcards generated from lecture notes covering Kinetic Molecular Theory, Intermolecular Forces, and Liquid Properties.

Kinetic Molecular Model

A model or representation used to explain how particles behave, focusing on visualizing particles and motion.

Kinetic Molecular Theory

A theory that explains the properties of solids and liquids in terms of intermolecular forces of attraction and the kinetic energy of individual particles.

Postulates of Kinetic Molecular Theory

1. All matter is made up of tiny particles. 2. These particles are in constant motion. 3. The speed of a particle is proportional to temperature (increased temperature means greater speed). 4. Solids, liquids, and gases differ in particle distances and the extent of particle interaction.

Effect of Temperature on Kinetic Energy

When temperature increases, the average kinetic energy of molecules increases, causing molecules to move with greater speed and intensity.

Intermolecular Forces of Attraction

Attractive forces between molecules or particles in the solid or liquid state.

van der Waals Forces

The collective term for intermolecular forces of attraction in a pure substance, including dipole-dipole, hydrogen bonding, ion-dipole, and London dispersion forces.

Dipole-Dipole Force

An intermolecular force that exists between polar molecules where one end of a dipole attracts the oppositely charged end of another dipole.

Hydrogen Bonding

A special and very strong type of dipole-dipole force that exists between a Hydrogen atom bound to a small and highly electronegative non-metal atom (specifically Nitrogen, Flourine, Oxygen).

Ion-Dipole Force

An intermolecular force acting between an ion (either positive or negative) and a polar molecule, which explains the solubility of ionic compounds.

London Dispersion Force

The weakest type of intermolecular force, formed when an instantaneous dipole moment occurs as two non-polar molecules approach each other.

Dissolution of Ionic Compounds in Water

The process in polar water where ions and oppositely charged ends of water molecules overcome ionic attractions, causing ions to separate and water molecules to cluster around them.

General Properties of Liquids

Properties explained qualitatively at the particulate level, including Surface Tension, Viscosity, Capillary Action, Heat of Vaporization, Vapor Pressure, and Boiling Point.

Viscosity

The resistance of a liquid to flow, loosely referred to as the thickness or thinness of a liquid; it increases with stronger intermolecular forces.

Liquid Surface Concavity

The downward curved surface (concave) formed by a liquid due to adhesive forces between the liquid and the container walls.

Vapor Pressure

The pressure exerted by a liquid's vapor when in equilibrium with its liquid or solid phase in a closed container.

Vapor Pressure of Water ($H_2O$)

Water, held by Hydrogen Bonding, has a vapor pressure of $0.03\,\text{atm}$.

Vapor Pressure of Ethyl Ether ($C_4H_{10}O$)

Ethyl Ether, influenced by dipole-dipole and London dispersion forces, has a vapor pressure of $0.68\,\text{atm}$.

Boiling Point

The temperature at which a liquid's vapor pressure is equal to the external or atmospheric pressure.

Molar Heat of Vaporization ($\Delta H_{\text{vap}}$)

The amount of heat required to vaporize one mole of a substance at its boiling point.

Unique Properties of Water

Characteristics of water, which include being a good solvent and possessing a high specific heat.

Specific Heat

The amount of heat required to raise the temperature of a given quantity of a substance.