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 transition of a substance from one state of matter to another, such as solid to liquid, due to energy changes.

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Example: This diagram shows how matter changes between solid, liquid, and gas states through processes like melting, freezing, vaporization, condensation, sublimation, and deposition.

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Plasma Noun

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[plaz-muh]

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Plasma

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A state of matter consisting of ionized gas with free electrons and ions, having no definite shape or volume.

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Example: This image shows a plasma ball, where electricity energizes a gas inside the sphere, turning it into glowing tendrils of plasma, the fourth state of matter.

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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 between neighboring molecules that determine a substance's physical properties like its boiling and melting points.

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Example: This diagram shows that intermolecular forces are the weak attractions (dashed lines) between separate water molecules, which must be overcome for phase changes like boiling.

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Endothermic Adjective

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[en-doh-thur-mik]

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Endothermic

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Describing a process or reaction that absorbs energy, typically in the form of heat, from its immediate surroundings.

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Example: This diagram shows a system absorbing heat from its surroundings, indicated by arrows pointing inward. This process of taking in energy is called endothermic.

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Melting Noun

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[mel-ting]

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Melting

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The phase transition process in which a substance changes from a solid to a liquid state by absorbing thermal energy.

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Example: This diagram shows that melting is the process where a substance, like an ice cube, changes from a solid state to a liquid 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 process by which a substance in a liquid state converts to a gaseous state, including boiling and evaporation.

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Example: This diagram shows vaporization as the process where liquid molecules gain energy, move faster and farther apart, and change into a gas.

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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 where a liquid turns into a gas at its surface, occurring at temperatures below its boiling point.

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Example: Heat energy from the sun causes liquid water to change into a gas (water vapor), which then rises into the air.

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Vapor Pressure Noun

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[vey-per presh-er]

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Vapor Pressure

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The pressure exerted by a vapor in equilibrium with its condensed phase at a specific temperature in a closed system.

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Example: In a closed container, some liquid particles escape to become gas. This gas, or vapor, creates pressure above the liquid, which is called vapor pressure.

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Boiling Point Noun

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[boil-ing point]

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Boiling Point

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The temperature at which a liquid's vapor pressure equals the external pressure, causing it to rapidly change into a gas.

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Example: This diagram shows that boiling occurs when bubbles of vapor form throughout the liquid, which happens when the liquid's vapor pressure equals the surrounding atmospheric pressure.

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Sublimation Noun

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[suhb-luh-mey-shuhn]

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Sublimation

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The phase transition of a substance directly from the solid to the gas state, without passing through the liquid state.

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Example: This diagram shows a solid turning directly into a gas, skipping the liquid phase. The arrow labels this process as sublimation.