Supplement to Section E.6 - Introduction to Energy

Vocabulary flashcards covering energy concepts, states of matter, phase changes, and energy transfer from the lecture notes.

Energy

The capacity to effect change; in chemistry, the ability to do work or cause a transformation.

Potential Energy

Energy stored in an object due to position or composition.

Kinetic Energy

Energy of movement; KE = 1/2 mv^2.

Thermal Energy

Energy associated with temperature and phase; arises from particle movement; in a given substance, different phases have different motion.

Temperature

The measure of a substance’s thermal energy.

Solid

State of matter with definite shape and volume; particles fixed in arrangement with strong attractions; they vibrate in fixed positions.

Liquid

State with definite volume but no definite shape; particles close, fluid; attractions between particles, but weaker than in a solid; they move randomly while staying near neighbors.

Gas

State with no definite volume or shape; expands to fill container; particles far apart; weak or no attractions; move randomly.

Phase Change

Transition between solid, liquid, and gas that involves gain or loss of heat.

Endothermic

Process in which the system gains energy (heat is absorbed); surroundings lose energy.

Exothermic

Process in which the system loses energy (heat is released); surroundings gain energy.

Fusion

Solid to liquid phase change (melting); typically endothermic.

Melting

Solid to liquid phase change; absorbs heat; endothermic.

Freezing

Liquid to solid phase change; releases heat; exothermic.

Vaporization

Liquid to gas phase change; absorbs heat; endothermic.

Condensation

Gas to liquid phase change; releases heat; exothermic.

Sublimation

Solid to gas phase change; absorbs heat; endothermic.

Deposition

Gas to solid phase change; releases heat; exothermic.

System

The substance undergoing the phase change.

Surroundings

Everything outside the system that exchanges energy with it.

First Law of Thermodynamics

Energy cannot be created or destroyed; it can only be converted between forms; total energy of the universe is constant.

Heat

Quantity of energy transferred due to a temperature difference; symbol q; flows from higher to lower temperature.

ΔT (Change in Temperature)

ΔT = Tfinal − Tinitial; positive means temperature increases, negative means temperature decreases.

Energy Diagram

Diagrams used to represent energy changes in a system, showing endothermic vs exothermic phase changes.

Temperature and Thermal Energy Relationship

A substance's temperature is proportional to its thermal energy.

Phase Changes and Thermal Energy

Phase changes occur due to gain or loss of thermal energy; endothermic adds energy, exothermic releases energy.

Particulate Differences Across Phases

Different phases differ in particle arrangement and motion, leading to different amounts of thermal energy.