Chapter 2: The Nature of Matter - Vocabulary Flashcards

Vocabulary flashcards covering key terms from the lecture notes on matter, its properties, changes, and mixtures.

Matter

Anything that has mass and takes up space.

Substance

Matter with a uniform and unchanging composition.

State of matter (phase)

One of the forms of matter: solid, liquid, or gas.

Phase

Another term for the state of matter.

Solid

A state with definite shape and volume; particles are tightly packed and vibrate.

Liquid

A state with definite volume but indefinite shape; flows and particles slide past one another.

Gas

A state with no definite shape or volume; expands to fill a container and is highly compressible.

Vapor

Gas form of a substance that is typically a solid or liquid under normal conditions.

Plasma

High‑temperature, ionized gas with charged particles; found in stars and lightning; not commonly studied here.

Physical property

Property observed or measured without changing the substance’s chemical composition.

Intensive property

Property that does not depend on the amount of substance (e.g., density, melting point, boiling point, color, odor).

Extensive property

Property that depends on the amount of substance (e.g., mass, length, volume).

Density

Mass per unit volume; an intensive physical property used to identify substances.

Chemical property

A substance’s ability to react to form new substances, or its lack of reactivity.

Mass

A measure of the amount of matter in an object; an extensive property often used in calculations.

Volume

The amount of space a substance occupies.

Phase change

A physical change that changes a substance’s state (e.g., melting, freezing, boiling, condensation).

Melting point

The temperature at which a solid changes to a liquid; an intensive property.

Boiling point

The temperature at which a liquid changes to a gas; an intensive property.

Condensation

Phase change from a gas to a liquid.

Vaporization

Phase change from a liquid to a gas; includes boiling and evaporation.

Physical change

A change that alters a substance without changing its chemical composition.

Chemical change

A change in which the substance’s chemical composition is altered to form new substances.

Reactants

Starting substances in a chemical reaction.

Products

Ending substances formed by a chemical reaction.

Law of Conservation of Mass

Mass cannot be created or destroyed in a chemical reaction; mass of reactants equals mass of products in a closed system.

Element

A substance that cannot be broken down into simpler substances by chemical or physical means.

Periodic table

A grid of elements organized by periods and groups with repeating chemical properties.

Period

A horizontal row in the periodic table.

Group (family)

A vertical column in the periodic table; elements in the same group have similar properties.

Element symbol

One- or two-letter abbreviation for an element; first letter capitalized, second lowercase.

Compound

Two or more elements chemically bonded; compounds have different properties from their constituent elements.

Law of Definite Proportions

A compound contains its elements in the same proportion by mass in all samples.

Percent by mass

Mass percent of an element in a compound: (mass of element / mass of compound) × 100%.

Law of Multiple Proportions

If two compounds are formed from the same elements but have different mass ratios, their element ratios are simple whole-number multiples.

Mixture

Two or more substances physically combined; components retain properties and composition varies.

Homogeneous mixture

A uniform mixture with a constant composition and a single phase (also called a solution).

Heterogeneous mixture

A non-uniform mixture where components remain distinct.

Filtration

Separation by particle size using a filter.

Distillation

Separation by differences in boiling points.

Sublimation

Solid changes directly to a gas, skipping the liquid phase.

Chromatography

Separation based on differential attraction between a mobile phase and a stationary phase; often used for colored solutions.

Crystallization

Separation by forming solid crystals as the solution evaporates.