Related to Chemistry that everyone can use to gain knowledge

1. Classification of Matter

2. Substances
• Matter that is either an element or a compound
• Elements and compounds can not be reduced to
more basic components by physical means

3. Elements
• All units that make up all
matter are called atoms
• If all the atoms in a
sample of matter have the
same identity, that kind of
matter is an element
• The carbon in a pencil
point contains only carbon
atoms, carbon is an
element

4. Compounds
• Compounds are material
made of two or more
elements combined
• The ratio of the different
atoms is always the same
for that compound
• Example: Waters ratio is
H2O, so in each water
molecule there are two
hydrogen atoms and one
oxygen atom

5. Element or Compound
Gold
Element
Au

6. Element or Compound
Salt
Compound
NaCl (sodium chloride)

7. Element or Compound
Copper
Element
Cu

8. Element or Compound
Baking soda
Compound
NaHCO3 (sodium bicarbonate)

9. Element or Compound
Propane
Compound
C3H8

10. Mixtures
• A mixture is a material
that is made up of two
or more substances
• Do not always contain
the same amounts of
substances that make
them up
• A heterogeneous mixture
is a mixture in which the
different materials can
easily be distinguished
• A homogenous mixture or
solution is a mixture in
which two or more
substances are uniformly
spread out and the
different materials can not
be easily distinguished

11. MATTER
Element
One kind of atom
Compound
Two or more
kinds of atoms
Substance
Composition definite
Homogeneous
Evenly mixed;
a solution
Heterogeneous
Unevenly
mixed
Mixture
Composition variable
Matter
Has mass
Takes up space

12. Colloids and Suspensions
• A colloid is a
heterogeneous mixture
containing tiny particles
that never settle out.
Example : milk and jello
• A suspension is a
heterogeneous mixture
containing a liquid in
which visible particles
settle. Example: Muddy
water

13. • One way to distinguish a colloid from a
solution is by its appearance.
Detecting Colloids
• Fog appears white because its particles are
large enough to scatter light.
• Sometimes it is not so obvious that a liquid
is a colloid.
• You can tell for certain if a liquid is a colloid
by passing a beam of light through it.

14. • A light beam is invisible as it passes through
a solution, but can be seen readily as it passes
through a colloid. This occurs because the
particles in the colloid are large enough to
scatter light, but those in the solution are not.
Detecting Colloids
• This scattering of
light by colloidal
particles is called
the Tyndall
effect.

16. • Some mixtures are neither solutions nor
colloids. One example is muddy pond
water.
Suspensions
• Pond water is a suspension, which is a
heterogeneous mixture containing a liquid
in which visible particles settle.

17. A. colloid
B. mixture
C. substance
D. solution
A _______ is a type of matter with a fixed
composition.
Question 1

18. The answer is C. A substance can be either
an element or a compound.
Answer

19. A. 5
B. 10
C. 30
D. 90
How many elements are found on Earth?
Question 2

20. The answer is D. About 90 elements are
found on Earth, and more than 20 have been
made in laboratories.
Answer

21. How are compounds different from mixtures?
Question 3

22. The atoms in compounds are combined in
fixed proportions and cannot be separated by
physical means. A mixture is made of two
or more substances that can be easily
separated by physical means.
Answer

23. Physical Properties
• A physical property is a
characteristic of a material
that you can observe with
out changing the
substances that make up
the material
• Physical properties can be
used to separate mixtures
• Examples of physical
properties include: color,
shape, size, density,
melting point, and boiling
point

24. Appearance
• How would you describe a tennis ball? You
could begin by describing its shape, color,
and state of matter.
• You can measure
some physical
properties, too. For
instance, you could
measure the diameter
of the ball.

25. Behavior
• Some physical properties describe the
behavior of a material or a substance.
• Attraction to a magnet is a physical property
of the substance iron.
• Every substance
has a specific
combination of
physical properties
that make it useful
for certain tasks.

26. Using Physical Properties to
Separate
• The best way to separate substances depends
on their physical properties.
• Size is one physical property often used to
separate substances.

27. Using Physical Properties to
Separate
• Look at the mixture of iron filings and sand
shown.
• You probably won’t be
able to sift out the iron
filings because they are
similar in size to the sand
particles. What you can
do is pass a magnet
through the mixture.

28. Using Physical Properties to
Separate
• The magnet attracts only
the iron filings and pulls
them from the sand.
This is an example of
how a physical property,
such as magnetic
attraction, can be used to
separate substances in a
mixture.

29. Physical Change
The Identity Remains the
Same
• These changes might involve energy changes,
but the kind of substance—the identity of the
element or compound—does not change.

30. Physical Change
• A physical change is a
change in size, shape, or
state of matter
• Physical changes do not
change the identities of the
substances of the material
• Physical changes can be
used to separate mixtures
• Physical changes can
sometimes be reversed
• Examples of physical
changes include phase
changes

31. • Iron is a substance that can change states if it
absorbs or releases enough energy—at high
temperatures, it melts.
The Identity Remains the
Same
• Color changes can
accompany a
physical change, too.

32. The Identity Remains the
Same
• For example, when
iron is heated it first
glows red. Then, if
it is heated to a
higher temperature,
it turns white.

33. Chemical Changes
• A change of one substance
in a material to a different
substance is a chemical
change
• Examples: When iron is
exposed to oxygen and
water in the air the iron
and oxygen form rust,
baking a cake
• Chemical Changes usually
can not be reversed

34. Chemical Change
• When a substance goes
through a chemical change
it may change the physical
and chemical properties of
the substance
• Sodium is a soft, metallic
(physical characteristic)
element that explodes
when exposed to any
moisture (chemical
characteristic)
• Chlorine is a deadly
(chemical
characteristic) green
(physical
characteristic) gas
(used in WWI)
• When combine
chemically they create
sodium chloride (table
salt)

36. • Clues such as heat, cooling, or the formation
of bubbles or solids in a liquid are helpful
indicators that a reaction is taking place.
The Identity Changes
• However, the only sure proof is that a new
substance is produced.
• The only clue that iron has changed into a
new substance is the presence of rust.
• Burning and rusting are chemical changes
because new substances form.

37. Using Chemical Change to Separate
• One case where you might separate
substances using a chemical change is in
cleaning tarnished silver.
• Tarnish is a chemical reaction between
silver metal and sulfur compounds in the air
which results in silver sulfide.
• It can be changed back into silver using a
chemical reaction.

38. • You don’t usually separate substances using
chemical changes in the home.
Using Chemical Change to
Separate
• In industry and chemical laboratories,
however, this kind of separation is common.
For example, many metals are separated from
their ores and then purified using chemical
changes.

39. Chemical Properties
• A characteristic of a
substance that
indicates whether it
can undergo a certain
chemical change
• Examples are
flammability, and
reacting with sunlight

40. • The forces of nature continuously shape
Earth’s surface. Rocks split, deep canyons
are carved out, sand dunes shift, and curious
limestone formations decorate caves.
Weathering—Chemical or
Physical Change?
• Do you think these changes, often referred to
as weathering, are physical or chemical? The
answer is both.

41. • Large rocks can split when water seeps into
small cracks, freezes, and expands.
Physical
• However, the smaller pieces of newly
exposed rock still have the same properties
as the original sample.
• This is a physical change.

42. • Solid calcium carbonate, a compound found
in limestone, does not dissolve easily in
water.
Chemical
• However, when the water is even slightly
acidic, as it is when it contains some
dissolved carbon dioxide, calcium carbonate
reacts.
• It changes into a new substance, calcium
hydrogen carbonate, which does dissolve in
water.

44. • A similar
chemical change
produces caves
and the icicle
shaped rock
formations that
often are found
in them.
Chemical

46. Conservation of Mass
• The mass of all
substances present
before a chemical
change equals the
mass of the substances
after the chemical
change

47. • Suppose you
burn a large log
until nothing is
left but a small
pile of ashes.
The Conservation of Mass
• At first, you might think that matter was lost
during this change because the pile of ashes
looks much smaller than the log did.

48. The Conservation of Mass
• In fact, the mass
of the ashes is less
than that of the
log.

49. • However, suppose that you could collect all
the oxygen in the air that was combined with
the log during the burning and all the smoke
and gases that escaped from the burning log
and measure their masses, too.
The Conservation of Mass
• Then you would find that no mass was lost
after all.

50. Section Check
A. boiling point
B. density
C. flammability
D. melting point
Which of the following is a chemical
property?
2
Question 1

51. Section Check
The answer is C. Flammability indicates
whether a substance will undergo the
chemical change of burning.
2
Answer

52. Section Check
A characteristic of a material that can be
observed without changing the identity of
the substances that make up the material is a
_______.
2
Question 2

53. Section Check
The answer is physical property. Examples
of physical properties include color, shape,
and density.
2
Answer

54. Section Check
What is the law of conservation of mass?
2
Question 3

56. Section Check
According to the law of conservation of
mass, the mass of all substances that are
present before a chemical change equals the
mass of all substances that remain after the
change.
2
Answer