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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.