Classification of Matter Ch. 15 Classification of Matter

Section 1: Composition of Matter Substance: Either an element or a compound Element: Substance made of all the same type of atom Ex: nugget of gold, piece of lead Compound: Substance made of two or more types of atoms combined in a fixed proportion Ex: water (H20), table salt (NaCl)

Section 1: Composition of Matter Mixture: Made of 2 or more substances that can be separated by physical means Heterogeneous mixture: Mixture of different and easily distinguishable materials (ex: trail mix) Homogeneous mixture: Contains 2 or more gaseous, liquid, or solid substances blended evenly Also called a solution (ex: soft drink)

Section 1: Composition of Matter Colloid: Heterogeneous mixture with larger particles that never settle Colloids scatter light in the Tyndall effect Ex: paint, fog Suspension: Heterogeneous mixture containing a liquid in which visible particles settle Ex: muddy pond water

Section 2: Properties of Matter Physical property: characteristics of a material which can be observed without changing the identity of the substances in the material examples: color, shape, size, melting point, and boiling point 1. Appearance—physical description of a substance 2. Behavior—how a substance acts; for example, magnetism, viscosity, ductility 3. Physical properties such as size and magnetism can be used to separate mixtures.

Section 2: Properties of Matter Physical change: change in a substance’s size, shape, or state of matter substance does not change identity when it undergoes a physical change Distillation: a process for separating a mixture by evaporating a liquid and condensing its vapor

Section 2: Properties of Matter Chemical property: characteristics of a substance indicating that it can change chemically for example: flammability or light sensitivity of a substance

Section 2: Properties of Matter Chemical Change: When one substance changes to another substance. Some chemical changes are indicated by temperature change, smell, or bubble formation. Other chemical changes occur very slowly such as the formation of rust. Chemical changes can be used to separate substances such as metals from their ores.

Section 2: Properties of Matter Weathering of Earth’s surface involves both physical and chemical changes. Physical—big rocks split into smaller ones; streams carry rock particles from one location to another Chemical—Chemical changes can occur in rocks when calcium carbonate in limestone changes to calcium hydrogen carbonate due to acid rain.

Section 2: Properties of Matter Law of Conservation of Mass Mass of all substances present before a chemical change equals the mass of all substances after the change.