Chemistry
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Matter is anything that
has mass and takes up
space.
All matter is made of
particles. The type and
arrangement of the
particles determines the
properties of the matter.
Most matter exists as
solids, liquids, or gases.
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Volume: the space an object takes up. Measured
by: calculating L X W X H, or in mL with a
Graduated Cylinder
Mass: the quantity of matter contained in an
object. Measured by: Triple-beam Balance or
Electronic Balance
Weight: the force produced by gravity acting on
the mass of an object. Scientists express force in
newtons, but they express mass in kilograms.
Because gravity varies from place to place,
weight can change but mass won’t.
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Physical Property= a
characteristic of a
substance that does
not involve a chemical
change.
These include: density,
color, what state of
matter it typically exists
in, hardness, melting
point or boiling point
Whether water is ice or liquid, it is
still water. Changing its state
doesn’t change its’ identity.
The sugar in the tea is still sugar,
even if it is dissolved in the water
of the tea.
Tearing paper
into pieces is
a physical
change—it is
still paper.
But, burning
it changes its
chemical
composition.
Burning paper
turns it into a
new
substance.
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Chemical Properties=
a property of matter
that describes a
substance’s ability to
participate in
chemical reactions.
Chemical properties
can only be
determined by trying
to cause a chemical
change! If it changes to
something else, that
was a chemical
change.
The Formation
of a Precipitate
The Release
or
Absorption
of Energy
The Evolution of a
Gas: the production of
a gas is often
observed by bubbling
A Color Change in
the Reaction System
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In an equation, the substances on the lefthand side of the arrow are the reactants. The
substances on the right side are the
products.
All physical and chemical changes involve a change
in energy. Energy is the ability to do work.
 Sometimes, energy must be supplied for the change
to occur.
 Other times, energy is released.
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Both of these
reactions involve
Hydrogen and
Oxygen—Water!
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Ice melting and water boiling are examples of
physical changes.
A physical change affects only the physical
properties of a substance.
When ice melts and turns into liquid water,
you still have the same substance
represented by the formula H2O. When
water boils and turns into vapor, the vapor is
still H2O. Only the physical state of the
substance is changed.
In contrast, the reaction of H and O to form
http://www.nsf.gov/news/special_reports/che
H2O is a chemical change.
mistrynow/chem_ice.jsp
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All matter is composed of about 110 different
kinds of atoms. Atoms can be physically
mixed or chemically combined to form all
kinds of matter.
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A pure substance is a sample of matter
(either a single element or a single
compound) that has definite chemical and
physical properties.
The helium atoms inside these
balloons are an example of a pure
substance.
The copper wire inside these
electrical cords is a pure substance.
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Elements are pure substances that contain
only one kind of atom.
Copper and Helium are elements.
Each element has its own unique set of
physical and chemical properties and is
represented by a distinct chemical symbol.
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Some elements (such as Helium) exist as
single atoms.
Other elements exist as molecules:
Molecule= the smallest unit of a
substance that keeps all of the
physical and chemical properties
of that substance; it can consist of
one atom or two or more atoms
bonded together.
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Pure substances that are not elements are
called compounds.
Compounds are composed of more than one
kind of atom.
Compounds are represented by formulas,
which show the ratio of the atoms.
The molecular formula and
structural diagram of Aspirin:
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A sample of matter that contains two or more
pure substances is a mixture.
Most kinds of food are mixtures (except for
sugar and salt).
Water is not a mixture of hydrogen and
oxygen—they are bonded as a molecule, not
just physically mixed. Also, the ratio of two
hydrogen to 1 oxygen is the same in every
molecule.
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A glass of sweetened lemonade is a mixture.
If you have ever had a glass that is just too
sweet or not sweet enough, you have
experienced a characteristic of mixtures.
A mixture doesn’t always
have the same balance of
ingredients. Therefore,
their properties can change.
Homogenous
Mixtures—describes a
mixture that has a
uniform distribution of
materials throughout.
 Ex: sweetened tea or
14 karat gold
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Heterogeneous
Mixtures—is composed
of components that are
dissimilar (not alike,
nor in equal quantities)
 Ex: Sand and water or a
salad
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Anything that has mass and
takes up space
All of the particles
(atoms or molecules) in
the sample are
identical to each other
Molecule:
A particle made of two or
more atoms bonded
together
Contains two or more
different types of particles
(atoms or molecules) not
bonded to each other
Pure substances
made of only one
type of atom
Pure substance made of
more than one type of
atom bonded together
Mixture made of different
types of particles that is
uniformly distributed
throughout.
Mixture that is made
of different types of
particles that do not
have equal quantities
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Your friend mentions that she eats only natural
foods because she wants her food to be free of
chemicals. What is wrong with this reasoning?
Is toasting bread an example of a physical or
chemical change? Why?
Classify each of the following as a physical change
or a chemical change and provide evidence:
a. cracking an egg
b. using bleach to remove a stain from a shirt
c. burning a candle
d. melting butter in the sun