The Particle Theory of Matter
 All matter is made up of extremely tiny
particles.
 Each pure substance has its own kind of
particle, different from the particles of other
pure substances.
 Particles attract each other.
 Particles are always moving.
 Particles at a higher temperature move faster
on average than particles at a lower
temperature.
Copy figure 5.1A, 5.1B, and 5.1C into your
notebooks
Define each of the following terms:
scientific model, heterogeneous, homogeneous,
solution, mechanical mixture, qualitative physical
property, and quantitative physical property
Scientific model: scientific models are used to help
scientists to picture, in an imaginative way, processes in
nature that cannot simply or directly be seen. Example:
The particle theory of matter.
Heterogeneous: is a term applied to mixtures that are
not found of a uniform composition throughout. It is an
uneven mixture that contains two or more substances.
Homogeneous: a term applied to pure substances and to
mixtures that are of a uniform composition throughout.
It is a mixture that is the same throughout.
Solution: a homogeneous mixture of two or more pure
substances.
Mechanical Mixture: a heterogeneous mixture where at
least two substances are visible.
Qualitative physical property: a characteristic of a
substance that can be described but not measured.
Examples: smell, state, taste, texture.
Quantitative physical property: a characteristic of a
substance that can be measured. Examples: density,
melting temperature, boiling temperature.
Chemical or Physical Changes/Properties
Physical Change is a change in matter in which no
new substance is formed. Examples: melting, density,
volume, mass, boiling, freezing, and evaporating.
Any property that can be observed or measured
without forming a new substance is a physical property.
Color and density are examples of physical properties.
Color can be observed without touching or changing,
density is the amount of matter that occupies a certain
space. Density can be measured without forming a new
substance so density is also a physical property.
Chemical Change is a change in matter in which at
least one new substance, with new properties, is formed.
Example: heat or light is given off (burning), bubbles
form, a new color appears, change is not easily reversible,
and a precipitate (solid material) forms in a liquid.
Any property that describes how a substance reacts
with another substance when forming a new substance is
called a chemical property. Combustibility is the ability
of a substance to burn in air and is therefore a chemical
property.