Ch. 15
Classification of Matter
1. Composition of Matter
a. Substance - either an element or a compound
i. Element – a substance where all atoms in it are the same.
ii. Compound – is a substance with two or more elements combined in a
fixed proportion.
b. Mixture – two or more substances that can be easily separated by physical
means.
i. heterogeneous mixture - substance in which its different components are
easily distinguished
ii. homogeneous mixture - substance containing two or more components
that are blended uniformly so that individual components are
indistinguishable with a microscope
iii. colloid - heterogeneous mixture whose particles never settle
iv. suspension - heterogeneous mixture containing a liquid, and in which
visible particles slowly settle due to gravity
v. Tyndall effect - tendency for a beam of light to scatter as it passes
through a colloid
2. Properties of Matter
a. physical property - any characteristic of a material, such as size or shape, that
can be observed without changing the identity of the material; examples include
color, shape, size, melting point and boiling point.
i. Appearance – physical description of a substance
ii. Behavior – how a substance act; for example, magnetism, viscosity,
ductility
iii. Physical properties such as size and magnetism can be used to separate
mixtures.
b. Physical change – change in a substance’s size, shape, or state of matter
i. Substance does not change identity when it undergoes a physical change
ii. Distillation is a process for separating a mixture by evaporating a liquid
and condensing its vapor.
c. Chemical property – characteristics of a substance indicating that it can change
chemically; for example, flammability or light sensitivity of a substance.
d. Chemical Change – occurs when one substance changes to another substance.
i. Some chemical changes are indicated by temperature change, smell or
bubble formation.
ii. Other chemical changes occur very slowly such as the formation of rust.
iii. Chemical changes can be used to separate substances such as metals
from their ores.
e. Weathering of Earth’s surface involves both physical and chemical changes.
i. Physical – big rocks split into smaller ones; streams carry rock particles
from one location to another.
ii. Chemical – chemical changes can occur in rocks when calcium carbonate
in limestone changes to calcium hydrogen carbonate due to acid rain.
f. Law of Conservation of Mass – Mass of all substances present before a chemical
change equals the mass of all substances after the change.
Ch. 15 Vocabulary
Chemical change - change of one substance into a new substance
Chemical property - any characteristic of a substance, such as flammability, that can be observed that
produces a new substance
Colloid - heterogeneous mixture whose particles never settle
Compound - substance in which the atoms of two or more elements are combined in a fixed proportion
Diffusion - spreading of particles throughout a given volume until they are uniformly distributed
Distillation - process that can separate two substances in a mixture by evaporating a liquid and
recondensing its vapor
Element - substance with atoms that are all alike
Heterogeneous mixture - substance in which its different components are easily distinguished
Homogeneous mixture - substance containing two or more components that are blended uniformly so
that individual components are indistinguishable with a microscope
Law of conservation of mass - states that the mass of all substances present before a chemical change
equals the mass of all the substances remaining after the change
Physical change - any change in size, shape, or state of matter in which the identity of the substance
remains the same
Physical property - any characteristic of a material, such as size or shape that can be observed without
changing the identity of the material
Solution - homogenous mixture, remains constantly and uniformly mixed and has particles that are so
small they cannot be seen with a microscope
Substance - element or compound that cannot be broken down into simpler components without losing
the properties of the original substance
Suspension - heterogeneous mixture containing a liquid, and in which visible particles slowly settle due
to gravity
Tyndall effect - tendency for a beam of light to scatter as it passes through a colloid