Key Concepts in Thermodynamics and States of Matter

Kinetic Energy and the Nature of Matter

• Kinetic Energy: The energy an object possesses due to its motion.
• Kinetic Theory: States that all matter is composed of tiny particles in constant motion.

Pressure and Its Measurement

• Gas Pressure: Results from the force exerted by a gas per unit surface area of an object.
• Vacuum: An empty space devoid of particles and pressure.
• Atmospheric Pressure: Arises from the collisions of atoms and molecules in the air with objects.
• Barometer: A device used to measure atmospheric pressure.
• Pascal (Pa): The SI unit of pressure.
• Standard Atmosphere (atm): The pressure required to support 760 mm of mercury in a mercury barometer at 25ºC.

Phase Transitions and States of Matter

• Vaporization: The conversion of a liquid to a gas or vapor.
• Evaporation: Occurs when this conversion happens at the surface of a non-boiling liquid.
• Vapor Pressure: A measure of the force exerted by a gas above a liquid.
• Boiling Point: The temperature at which the vapor pressure of a liquid equals the external pressure.
• Normal Boiling Point: The boiling point of a liquid at a pressure of 101.3 kPa.
• Melting Point: The temperature at which a solid transitions into a liquid.
• Freezing Point: The temperature at which a liquid transitions into a solid.

Crystalline and Amorphous Solids

• Crystal: A solid with particles arranged in an orderly, repeating, three-dimensional pattern known as a crystal lattice.
• Unit Cell: The smallest group of particles within a crystal that retains its geometric shape.
• Allotropes: Two or more distinct molecular forms of the same element in the same physical state.
• Amorphous Solid: A solid lacking an ordered internal structure.
• Glass: A transparent fusion product of inorganic substances that have cooled to a rigid state without crystallizing.

Sublimation and Phase Diagrams

• Sublimation: The direct transition of a substance from a solid to a vapor, bypassing the liquid state.
• Phase Diagram: A graph illustrating the temperature and pressure conditions under which a substance exists as a solid, liquid, or gas.
• Triple Point: The unique set of conditions where all three phases can coexist in equilibrium.