Modeling Phase Changes

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Phase Change Noun

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[fayz cheynj]

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Phase Change

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A transformation of a substance from one state of matter, such as solid, liquid, or gas, to another.

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Example: Adding energy (heat) causes a substance like water to change phase, from a solid (ice) to a liquid (water) to a gas (steam).

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Kinetic Energy Noun

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[ki-net-ik en-er-jee]

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Kinetic Energy

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The energy that particles of a substance possess due to their motion, which is directly related to their temperature.

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Example: This diagram shows that particles in a gas have the highest kinetic energy (fastest motion), while particles in a solid have the lowest (vibrating in place).

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Intermolecular Forces Noun

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[in-ter-muh-lek-yuh-ler for-ses]

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Intermolecular Forces

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The attractive forces that exist between molecules, which influence the bulk properties of a substance like its boiling point.

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Example: This diagram shows how water molecules are attracted to each other by intermolecular forces, called hydrogen bonds, which hold the molecules together in a liquid or solid state.

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Intramolecular Forces Noun

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[in-truh-muh-lek-yuh-ler for-ses]

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Intramolecular Forces

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The forces, such as covalent or ionic bonds, that hold atoms together within a single molecule or formula unit.

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Example: This image shows the strong intramolecular force (a chemical bond) holding a hydrogen (H) and chlorine (Cl) atom together within a single molecule.

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Melting Noun

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[mel-ting]

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Melting

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The phase change process in which a substance transitions from a solid to a liquid state upon heating.

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Example: This diagram shows a solid ice cube transforming into a liquid puddle, illustrating the process of melting as a change in the state of matter.

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Melting Point Noun

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[mel-ting point]

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Melting Point

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The specific temperature at which a solid substance absorbs enough energy to become a liquid at a given pressure.

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Example: This graph shows that as heat is added, a substance's temperature is constant at its melting point (the flat line at 0°C) while it changes from solid to liquid.

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Freezing Noun

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[free-zing]

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Freezing

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The phase change process in which a substance transitions from a liquid to a solid state by removing heat.

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Example: This diagram shows that freezing is the process where a substance changes from a liquid state to a solid state.

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Vaporization Noun

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[vey-per-uh-zey-shuhn]

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Vaporization

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The general term for the phase change of a substance from a liquid to a gas, including evaporation and boiling.

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Example: This image shows vaporization by comparing its two types: evaporation, where particles escape from the surface, and boiling, where particles escape from throughout the liquid.

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Evaporation Noun

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[ih-vap-uh-rey-shuhn]

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Evaporation

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A type of vaporization that occurs at the surface of a liquid at temperatures below its boiling point.

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Example: This diagram shows energy from the sun causing water from the ocean to turn into vapor and rise into the air, which is evaporation.

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Condensation Noun

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[kon-den-sey-shuhn]

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Condensation

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The phase change process of a substance transitioning from a gas or vapor to a liquid state upon cooling.

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Example: Warm, moist air (gas) cools when it touches a cold surface, causing the water vapor to change into liquid water droplets.