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Ch. 4 Section 1
 Substance
either an element or a compound
cannot be broken down into simpler components
and still maintain the properties it had originally
 Element-
a substance in which all atoms are
alike
 Elements in nature are stable

Elements from labs are unstable - exist only for
short periods of time
 Aluminum-
can be used as a blanket because
it reflects radiation (a form of heat)
 Americium-
used in smoke detectors-
radioactive
 Tungsten-
very high melting point- used in
lightbulb filaments
 Titanium-
very lightweight and strong metalused in frames for airplanes and in engines
 Lead-
high density- makes it a good barrier for
radiation- blocks particle movement
 Gold- used for coating space vehicles and other
electronics

Resists corrosion & reflects infrared
 Compounds-
substance in which the atoms of two or
more different elements are combined in fixed
proportions


Elements bond to form compounds
Cannot be separated by physical means
C
Element - Atom
S8 Element- Molecule
H2O Compound
Cl2 Element- Molecule
H2O2 Compound
Mixture- made up of two or more
substances- can be separated by physical
means
Heterogeneous-made of materials that can
be distinguished from each other


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


Not uniform in composition
 Homogenous-
contains two or more gaseous, liquid, or
solid substance blended evenly throughout
 Solution- homogeneous mixtures containing particles
so small they cannot be seen with a microscope and
will never settle to the bottom of the container- tap
water, salt water, food coloring and water
 Colloid- mixture with large particles that never settlefog, smoke, ink, glue, milk, cream, butter
 Colloid
vs. Solution-pass a beam of light
through the mixture


If the beam is invisible- it is a solution
If the beam is visible- it is a colloid

The visible beam through the colloid is called the
Tyndall effect
 Suspension-
heterogeneous mixture
containing a liquid in which visible particles
settle out over time – like dirty water
 http://www.docbrown.info/page12/gifs/Ele
CpdMixALL.gif
 How
can you tell the difference between
mixture and compound?
 Mixture can be separated physically and keep
its properties
 Compound can only be separated chemically
and does NOT keep its properties
Ch. 4 Section 2

Physical Property- any characteristic of a material
that you can observe or attempt to observe without
changing the identity of the substance

For example: color, shape, size, melting point, and boiling
point.
Behavior of substances- magnetism, ductility- ability
of metal to be drawn into wires; malleabilityability of metal to be shaped- pounded into sheets;
ability to flow
 Physical Change- IDENTITY DOES NOT CHANGE



a change in size, shape, or state of matter
may or may not involve energy changes and color changes
 Distillation-
separating a mixture through
evaporating a liquid and re-condensing its
vapor.

Vapors from the liquid with the lowest boiling
point form first and are condensed and collected
 Chemical
Property- characteristic of a
substance that indicates whether it can
undergo a certain chemical change
Chemical Change- change in identity- changes the
COMPOUND or SUBSTANCE
 Dark bottles- block light- prevents change in
identity
 Indications that a chemical change MAY have
occurred:



Smell, heat, light, sound, color change, production of gas or
precipitate
Color change does not always indicate a chemical
change

Example: blue and yellow make green- physical change- just
a mixture
 http://www.ric.edu/faculty/ptiskus/chemica
l/
 Chemical
changes can be used to separate
substances- done in labs- metals can be
removed from ore this way
 Weathering

Physical change when rocks split as water freezes or
as erosion occurs
Chemical change when acidic water reacts with
limestone and results in a new substance that
dissolves in water and washes away.
 Mass
cannot be created or destroyed

Burning a log seems to make mass disappear
“missing” mass is actually present in the gases
that are produced as the log burns

http://www.quia.com/quiz/303980.html
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