Physical and Chemical Changes

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Physical Property Noun

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[fiz-i-kuhl prop-er-tee]

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Physical Property

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A characteristic of a substance that can be observed or measured without changing the substance's chemical identity.

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Example: This diagram shows dissolving, a physical change. The ability of the solute (cubes) to dissolve in the solvent (liquid) is solubility, which is a physical property.

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Physical Change Noun

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[fiz-i-kuhl cheynj]

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Physical Change

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A change affecting the form of a substance, such as its state or shape, without creating a new substance.

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Example: This image shows that when ice cubes melt into liquid water, the substance's form changes, but its chemical identity and mass (100g) remain the same.

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Chemical Change Noun

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[kem-i-kuhl cheynj]

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Chemical Change

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A process that involves the formation of one or more new substances with different properties from the original substance.

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Example: Adding hydrochloric acid to iron powder causes a chemical reaction, creating gas bubbles. This shows a new substance (a gas) has been formed.

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Chemical Reaction Noun

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[kem-i-kuhl ree-ak-shun]

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Chemical Reaction

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A process that leads to the chemical transformation of one set of chemical substances to another; also called a chemical change.

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Example: In a chemical reaction, starting molecules (reactants) rearrange their atoms to form completely new molecules (products), as shown by the transformation on the flashcard.

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Density Noun

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[den-si-tee]

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Density

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A physical property of a substance defined as the amount of mass contained within a specific unit of volume.

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Example: This image shows that a pumice stone is less dense than water and floats, while an obsidian stone is more dense than water and sinks.

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Mass Noun

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[mas]

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Mass

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A fundamental physical property that measures the total amount of matter contained within a substance or an object.

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Example: This balance scale shows that the apple has more mass than the 1-gram weight, causing the scale to tip down on the apple's side.

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Volume Noun

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[vol-yoom]

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Volume

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A physical property that quantifies the amount of three-dimensional space occupied by a substance, object, or enclosed space.

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Example: This image shows that volume is the amount of space an object occupies, calculated for a cube by multiplying length, width, and height.

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Luster Noun

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[luhs-ter]

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Luster

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A physical property describing the way light interacts with the surface of a substance, often characterized as shiny or dull.

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Example: The shiny surface of the gold bars reflects light, which is an example of the physical property called luster.

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Sublimation Noun

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[sub-li-mey-shun]

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Sublimation

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A physical change where a substance transitions directly from the solid state to the gas state without becoming a liquid.

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Example: This diagram shows that sublimation is a physical change where a substance turns directly from a solid (like the cube) into a gas (like the cloud).

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Reversible Adjective

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[ri-vur-suh-buhl]

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Reversible

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A characteristic of a process or change that can be undone, allowing the substance to return to its original state.

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Example: This diagram shows that changes between states of matter, like melting and freezing, are reversible because the arrows show the process can go in both directions.