Unit 1: Particle Arrangement, Motion, Phase Changes, and Thermodynamics Study Guide

Recommended Study Resources:
- Vocabulary Study Material
- Class notes and practice
- Past quizzes

Solid:
- Shape: Definite shape.
- Volume: Definite volume.
- Particle Movement: Particles vibrate in place with the slowest speed.
- Kinetic Energy: Contains the least kinetic energy ( $\text{KE}$ ).
- Example: Mountain.
Liquid:
- Shape: Indefinite (changes) shape.
- Volume: Definite volume.
- Particle Movement: Particles flow past one another at a medium speed.
- Kinetic Energy: Contains a medium amount of kinetic energy ( $\text{KE}$ ).
- Example: Water.
Gas:
- Shape: Indefinite (changes) shape.
- Volume: Indefinite volume.
- Particle Movement: Particles move at fast speed, bouncing off one another and the container walls.
- Kinetic Energy: Contains high kinetic energy ( $\text{KE}$ ).
- Example: Carbon dioxide.
Plasma:
- Shape: Indefinite shape.
- Volume: Indefinite volume.
- Particle Movement: Particles move extremely fast; composed of electrified gas.
- Kinetic Energy: Contains high kinetic energy ( $\text{KE}$ ).
- Example: Sun.
Examples and Non-Examples of Matter:
- Examples of Matter: Oxygen, mountain, water.
- Examples of Non-Matter: Notebook, force, air conditioning.

Phase Transition Processes:
- Condensation: The process when a gas changes into a liquid.
- Melting: The process when a solid changes into a liquid.
- Freezing: The process when a liquid changes into a solid.
- Vaporization / Boiling: The process when a liquid changes into a gas.
- Sublimation: The process when a solid changes directly into a gas.
- Deposition: The process when a gas changes directly into a solid.
Thermal Energy and Particle Kinetics:
- Energy Removal: Changing matter from a liquid state to a solid state requires the removal of energy.
- Energy Addition: Changing matter from a liquid state to a gas state requires the addition of energy.
- Kinetic Energy Definition: The movement of particles in matter is defined as kinetic energy.
- Absolute Zero Temperature: Absolute zero occurs at $0\,\text{Kelvin}$ .
- Absolute Zero Motion: At absolute zero ( $0\,\text{Kelvin}$ ), the motion of particles in matter completely stops.

Components of a Heating Curve:
- Solid Phase: Located below the melting point temperature.
- Melting Point Plateau: Represents the transition from solid to liquid at 0\,\text{^\n\circ C}.
- Liquid Phase: Located between the melting point (0\,\text{^\n\circ C}) and boiling point (100\,\text{^\n\circ C}).
- Boiling Point Plateau: Represents the transition from liquid to gas at 100\,\text{^\n\circ C}.
- Gas Phase: Located above the boiling point temperature.
Energy Directionality:
- Across the progression of time on a standard heating curve, thermal energy is continually being added to the substance.
Phase Identification at Specific Temperatures:
- At -10\,\text{^\n\circ C}: The substance is in the solid state.
- At 50\,\text{^\n\circ C}: The substance is in the liquid state.
- At 120\,\text{^\n\circ C}: The substance is in the gas state.

Mount St. Helens Elevation Scenario:
- Observation: Stephanie climbs Mt. St. Helens and notices that at the base of the mountain, her water boils at a higher temperature than when she reaches the peak.
- Atmospheric Explanation: Water boils at a higher temperature at the bottom of the mountain due to higher air pressure. As elevation increases toward the mountain peak, air pressure decreases. This drop in atmospheric pressure allows water molecules to escape into the vapor phase more easily, lowering the boiling point temperature.

Regions and Critical Points of a Phase Diagram:
- Solid Region: Exists at lower temperatures and higher pressures (top-left domain).
- Liquid Region: Exists at intermediate temperatures and higher pressures (top-middle domain).
- Gas Region: Exists at higher temperatures and lower pressures (bottom-right domain).
- Triple Point: The specific state where solid, liquid, and gas phases coexist simultaneously in equilibrium. For this substance, the triple point occurs at a pressure of $0.65\,\text{atm}$ and a temperature of 200\,\text{^\n\circ C}.
- Critical Point: The point beyond which distinct liquid and gas phases do not exist. For this substance, the critical point occurs at a temperature of 825\,\text{^\n\circ C}.
Substance State Evaluations:
- At a temperature of 300\,\text{^\n\circ C} and a pressure of $1.75\,\text{atm}$ , the substance is in the liquid state.
- At a temperature of 200\,\text{^\n\circ C} and a pressure of $0.50\,\text{atm}$ , the substance is in the gas state.
- The pressure at which this substance exists in all 3 phases simultaneously is $0.65\,\text{atm}$ .
- The temperature at which this substance exists in all 3 phases simultaneously is 200\,\text{^\n\circ C}.
- If the pressure is held constant at $1.50\,\text{atm}$ and the temperature increases from -100\,\text{^\n\circ C} to 300\,\text{^\n\circ C}, the phase change that occurs is melting (transitioning from solid to liquid).