ACCL Chemistry – Chapter 1: Matter and Scientific Method

Vocabulary flashcards covering key terms from Chapter 1 lecture on matter, properties, classification, and scientific method.

Chemistry

The scientific study of matter, its properties, the changes it undergoes, and the energy associated with those changes.

Matter

Anything that has mass and occupies volume.

Physical Property

A characteristic that can be observed or measured without changing a substance’s chemical identity (e.g., melting point, density).

Chemical Property

A characteristic that becomes evident only during a chemical change, indicating a substance’s ability to form new substances (e.g., flammability).

Intensive Property

A physical property that does not depend on the amount of matter present (e.g., temperature, density).

Extensive Property

A physical property that depends on the amount of matter present (e.g., mass, volume).

Solid

State of matter with fixed shape and fixed volume; not compressible and does not flow.

Liquid

State of matter with indefinite shape, fixed volume; not compressible but flows.

Gas

State of matter with indefinite shape and volume; compressible and flows.

Crystalline Solid

A solid whose particles are arranged in an orderly, repeating geometric pattern (e.g., salt, diamond).

Amorphous Solid

A solid whose particles lack a long-range orderly pattern (e.g., glass, plastic).

Phase Change

A physical change in state—such as melting or boiling—requiring heating or cooling.

Melting

Physical change from solid to liquid.

Boiling

Physical change from liquid to gas throughout the liquid at its boiling point.

Sublimation

Physical change from solid directly to gas.

Deposition

Physical change from gas directly to solid.

Condensation

Physical change from gas to liquid.

Freezing

Physical change from liquid to solid.

Compressibility

The ability of a substance, especially a gas, to decrease in volume under pressure.

Pure Substance

Matter with constant composition; all samples have identical pieces in the same percentages.

Mixture

A combination of two or more pure substances that can be separated by physical methods and may vary in composition.

Homogeneous Mixture

Also called a solution; uniform composition and properties throughout the sample.

Heterogeneous Mixture

A mixture with regions of different composition and properties; components are visibly distinct.

Element

A pure substance consisting of only one type of atom that cannot be decomposed by chemical change.

Compound

A pure substance composed of two or more elements chemically combined; can be decomposed by chemical change.

Molecule

The smallest unit of a substance that retains its chemical properties, consisting of two or more chemically bound atoms.

Physical Change

A change in form or state that does not alter the chemical identity of the substance (e.g., dissolving salt in water).

Chemical Change

A process that transforms one or more substances into new substances with different molecular compositions.

Law of Conservation of Mass

Principle stating that matter is neither created nor destroyed in a chemical reaction; total mass of reactants equals total mass of products.

Scientific Method

A systematic approach to learning involving observation, hypothesis formulation, experimentation, and conclusion.

Hypothesis

A tentative, testable explanation for an observation or phenomenon.

Theory

A well-substantiated explanation of some aspect of nature that unifies many observations and hypotheses.

Scientific Law

A concise statement that summarizes a pattern found in nature, describing what happens without explaining why.

Distillation

Physical separation technique that separates components of a mixture based on differences in boiling point.

Filtration

Physical separation method that removes a solid from a liquid by passing the mixture through filter paper.

Chromatography

Technique that separates mixture components based on their differing adherence to a stationary surface and mobile phase.

Centrifugation

Separation method that uses rapid spinning to separate components based on density differences.

Decanting

Process of carefully pouring off a liquid to leave solid or denser liquid behind, exploiting density differences.

Density

Mass per unit volume of a substance; an intensive physical property.

Volatility

A measure of how readily a substance vaporizes; related to boiling point.