States of Matter and Phase Changes

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Solid Noun

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[sol-id]

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Solid

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A state of matter that has a definite shape and a definite volume, where particles vibrate in fixed positions.

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Example: This image shows a solid (ice cubes) and its microscopic view, where particles are tightly packed in a fixed, orderly pattern, giving it shape.

Front

Liquid Noun

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[lik-wid]

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Liquid

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A state of matter that has a definite volume but no definite shape, where particles can slide past each other.

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Example: This diagram shows that in a liquid, particles are close together but can move past one another, which is why liquids can flow and take the shape of their container.

Front

Gas Noun

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[gas]

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Gas

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A state of matter with no definite shape or volume, which expands to fill its container and has low density.

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Example: This diagram shows that in a gas, particles are far apart, move randomly and quickly, and expand to fill the entire container.

Front

Vapor Noun

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[vay-per]

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Vapor

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The gaseous state of a substance that is normally a liquid or solid at room temperature.

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Example: When liquid water is heated, it boils and turns into steam, which is a type of vapor in the gas state.

Front

Crystalline lattice Noun

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[kris-tuh-lin lat-is]

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Crystalline lattice

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The regular, repeating, three-dimensional arrangement of particles that is characteristic of many solids.

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Example: This image shows how atoms in a crystalline solid are arranged in an orderly, repeating, layered pattern called a crystalline lattice.

Front

Amorphous solid Noun

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[uh-mor-fus sol-id]

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Amorphous solid

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A solid in which the constituent particles are not arranged in a regular, repeating, or ordered pattern.

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Example: This image shows that in an amorphous solid, like the rock shown, the atoms are arranged in a disordered, random pattern, unlike the neat, repeating patterns in crystalline solids.

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Thermal energy Noun

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[thur-muhl en-er-jee]

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Thermal energy

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The total internal kinetic energy of the particles in a substance, often referred to as heat energy.

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Example: This diagram shows that thermal energy naturally flows as heat from a hotter object (red block) to a colder object (blue block).

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Heat Flow Noun

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[heet floh]

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Heat Flow

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The transfer of heat energy from an object of higher temperature to one of lower temperature.

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Example: This diagram shows the three ways heat flows: radiation from the fire, convection currents in the boiling water, and conduction through the pot's handle.

Front

Phase Change Diagram Noun

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[fayz cheynj dahy-uh-gram]

Back

Phase Change Diagram

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A graph showing changes in temperature versus heat energy added to a substance as it changes state.

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Example: This diagram shows the three states of matter (solid, liquid, gas) and the six processes, like melting and freezing, that change one state to another.

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Melting Noun

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[mel-ting]

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Melting

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The phase change from a solid to a liquid, which occurs when a substance absorbs thermal energy.

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Example: This diagram shows the process of melting, where a substance in its solid state, like an ice cube, changes into its liquid state.