Matter
t Matter:
anything that has mass and volume
t States of matter:
solid, liquid, gas, and plasma
t Changes in state such as boiling (liquid to gas) are
physical changes
t Properties of matter:
the set of characteristics by which a substance is recognized.
t Properties describe
t What can be observed by examining the substance
t The way a substance behaves when brought into contact
with other substances or exposed to sources of energy
Physical vs. Chemical
t Physical Properties: can be
observed without altering the identity of the substance. Examples include density, color, and melting
point
t Physical Changes: DO NOT alter
the identity of the substance. Examples
include crushing, tearing and changes in state.
t Chemical Properties: describe how
a subtance interacts (or fails to interact) with other substances. These CANNOT be observed without altering
the substance. Example: flammability
t Chemical Changes: Alter the
identity of the substance.
Example: burning
Evidence of Chemical Change
tHeat
energy is released or absorbed
tEnergy
is released as light
tUnexpected
Color change:
tEx: Clear + Blue = Green
tUnexpected
phase change –
tGas
bubbles form in liquid mixture
tPrecipitate
– solid forms in liquid mixture
Law of Conservation of Matter
tMatter
is neither created nor destroyed in any process
tThis
is for chemical changes
tNo
measurable change in mass takes place during an ordinary chemical reaction
Classify Matter
t
Pure substances: have a unique set of chemical and physical
properties
t
Elements: cannot be
separated into a simpler substance by a chemical change
t
Compounds: contains 2 or more elements combined in
fixed proportions
t
Mixtures: a blend of two or more pure substances –
t
each pure substance retains its individual
properties
t
The composition of
mixture can vary widely
Types of Mixtures
t Heterogeneous mixtures: have visibly different parts
t Example:
Chocolate chip cookies, egg salad
t Homogeneous mixtures:
do not contain visibly different parts.
t A sample from one part of the mixture will have the
same composition as a sample from any other part of the mixture.
t Example:
Gatorade
t Mixtures can be separated by physical means such as
filtration, distillation, crystallization and decanting.
Types of Mixtures
tSuspension: heterogeneous mixture - large particles that
will settle upon standing, are visible, and can be filtered out.
tColloid: appears to be homogeneous, but clouidy. Particles are too small to be seen, will not
settle out, but can be filtered out.
Thus, the mixture is two phases.
tSolution: Homogeneous mixtures made up of two or more
substances in a single physical state.
t even if the the
components were in different phases before the solution was formed.