Chemistry
Describing Matter
 Matter – anything
that has a mass
and takes up
space.
 Air, plastic, metal
wood, glass,
paper, and water
are all matter.
Most matter exists in three states!
 Solids – have a definite shape and
volume.
 The atoms of solids are in a fixed
position and are closely packed together.
Liquids
 Liquids have a definite
volume but no shape
of its own.
 The atoms are free to
move, which allow
liquids to flow from
place to place.
Gases
 Gases – have no definite shape or
volume.
 The atoms of gases spread apart filling
all the space available.
Melting
 The change from a solid to a liquid is
called melting.
 As a substance is melting, the particles
of a solid are vibrating so fast that they
break free from their fixed position.
Freezing
 The change of
state from a
liquid to a solid
is called
freezing.
 At its freezing
temperature,
the particles of a
liquid are
moving so
slowly they
Vaporization
 Vaporization – liquid to
a gas
 Two types of
vaporization
 Evaporation –
vaporization that
takes place on the
surface of a liquid.
 Boiling – occurs when
liquid changes to a
gas below its surface
as well as at the
surface.
Condensation
 Gas turns into a liquid. Condensation
occurs when particles in a gas lose
enough energy to form a liquid.
Chemistry
 Chemistry is the
study of matter and
how it changes.
 Iron changes to rust
in the presence of
water and oxygen.

A pure substance is a
single kind of matter that is
pure, meaning it always has
a specific makeup-or
composition. The two types
of pure substances are:
 Elements
 Compound
Compounds


Elements are the simplest
substances.
 They are composed of just
one pure substance.
A compound is a pure
substance made of two or more
elements chemically combined
in a set ratio. (It can be
represented by a chemical
formula).
 CO2 is the chemical formula
for the compound carbon
dioxide.
 C12H22O11 is the
chemical formula for
the compound table
sugar.
Mixtures
 A mixture is made of two or more
substances – elements, compounds, or
both that are together in the same place
but are not chemically combined.
 Mixtures can be separated by magnetic
attraction, filtration, and vaporization.
Types of Mixtures
 Homogenous Mixture
– the substances are
so evenly mixed that
you cant see the
different parts.
 Heterogeneous
Mixture – you can
see the different
parts. Salads and
soil is examples of
heterogeneous
mixtures.
Solution
 a mixture of two or more substances that is identical
throughout
Salt water is
 can be physically separated
considered a
solution.
How
 composed of solutes and solvents
can it be
physically
separated?
the substance in the smallest
amount and the one that
dissolves in the solvent
Iced Tea Mix
(solute)
the substance in the larger
amount that dissolves the
solute
Iced Tea
(solution)
Water
(solvent)
Solubility
 the amount of solute that dissolves in a certain
amount of a solvent at a given temperature and
pressure to produce a saturated solution
 influenced by:
What do we call things
that are not soluble?
Temperature
Pressure
Solids increased temperature causes
them to be more soluble and vice versa
Solids increased pressure has no
effect on solubility
Gases increased temperature causes
them to be less soluble and vice versa
Gases increased pressure causes them
to be more soluble and vice versa
Ex. Iced Coffee
Ex. Soda, “The Bends”
Change?
Physical Change occurs when a
substance changes in shape,
size or state of matter BUT it
remains the same substance.
Ex: Tearing a piece of paper, melting ice
evaporating alcohol, crushing chalk.
Phase changes are always PHYSICAL!
What are the 6 phase changes?
Comparing Physical and
Chemical Changes
Chemical Changes
Occurs when One or more substances
combine or decompose to form a
NEW substance. Elements combine
and recombine, breaking and/or
forming new bonds.
Ex: burning wood, baking bread, rusting
metals, fire works exploding
4 Evidences of Chemical
Changes
1. Color change
2. Gas is produced
- bubbles, odor, explosion
3. Temperature change
-Exothermic- Gives off Heat
-Endothermic- Absorbs heat
4. Precipitation: a solid is formed