Chapter 3: Matter and Energy
 With your partner, decide whether the
items on the card are matter or not matter.
 Create a list of properties that apply to all
items that you consider to be matter.
 Place the cards in the appropriate place on
the board once you are finished.
 Classify matter as element, compound,
or mixture.
 Distinguish between heterogeneous
and homogeneous mixtures.
 Matter: anything that occupies space and
has mass.
 Some types of matter, such as steel, water, wood,
and plastic, are easily visible to our eyes.
 Other types of matter, such as air or microscopic
dust, are impossible to see without magnification.
 Matter is ultimately
composed of atoms.
 Atoms: submicroscopic
particles that are the
fundamental building
blocks of matter.

In many cases, these
atoms are bonded
together to form
molecules.
 Molecules: two or more
atoms joined to one
another in specific
geometric arrangements.
 Recent advances in microscopy have
allowed us to image the atoms and
molecules that compose matter.

Scanning tunneling
microscope image of
nickel atoms

A scanning tunneling
microscope (STM) creates
an image by scanning a
surface with a tip of
atomic dimensions.
(Source: Reprint Courtesy of International
Business Machines Corporation,
copyright © International Business
Machines Corporation.)

Scanning tunneling
microscope image of a
DNA molecule

In this image, the DNA
molecule is yellow.

The double-stranded
structure of DNA is
discernible.
 The common states of matter are solid,
liquid, and gas.
 Plasma
 Bose Einstein Condensate

Water exists as ice (solid), water (liquid), and steam (gas).
 In ice, the water molecules are closely spaced and, although
they vibrate, they do not generally move relative to one
another.
 In liquid water, the water molecules are closely spaced but are
free to move around and past each other.
 In steam, water molecules are separated by large distances
and do not interact significantly with one another.

In solid matter, atoms or molecules
pack close to each other in fixed
locations.
 Neighboring atoms or molecules in a solid
may vibrate or oscillate, but they do not
move around each other.
 Solids have fixed volume and rigid shape.
 Examples: Ice, diamond, quartz, and iron
 Crystalline solid: Atoms or molecules are
arranged in geometric patterns with longrange, repeating order.
 Examples: salt, diamond
▪ The well-ordered, geometric shapes of salt and
diamond crystals reflect the well-ordered
geometric arrangement of their atoms.
 Amorphous solid: Atoms or molecules
do not have long-range order.
 Examples: glass, rubber, and plastic

In liquid matter, atoms or molecules are close to
each other but are free to move around and by
each other.
 Liquids have a fixed volume because their atoms
or molecules are in close contact.
 Liquids assume the shape of their containers
because the atoms or molecules are free to move
relative to one another.
 Examples: Water, gasoline, alcohol, and mercury

In gaseous matter, atoms or molecules are
separated by large distances and are free to
move relative to one another.
 Since the atoms or molecules that compose
gases are not in contact with one another, gases
are compressible.
 Gases always assume the shape and volume of
their containers.
 Examples: Oxygen, helium, and carbon dioxide
 Which image best represents matter in
the gas state?
 Pure substance: composed of only one
type of atom or molecule.
 Mixture: composed of two or more
different types of atoms or molecules
combined in variable proportions.
 Pure substances include elements and
compounds

Element: A pure substance that cannot be
broken down into simpler substances.
 No chemical transformation can decompose an
element into simpler substances.
 All known elements are listed in the periodic
table.
▪ Examples: hydrogen (H), carbon (C), iodine (I)

Compound: A pure substance composed of two or more
elements in fixed definite proportions.
 Compounds are more common than pure elements.
 Most elements are chemically reactive and combine with
other elements to form compounds.
 Compounds can be decomposed into simpler substances.
▪ Examples: water, table salt, sugar
Molecule/compound
Molecule/element
Atoms/element
Molecule/compound
 Pure substances can be represented
with a chemical formula.
 Examples?

When matter contains two types of atoms, it
may be a pure substance or a mixture.
 A compound is a pure substance composed of
different atoms that are chemically bonded in
fixed definite proportions.
 A mixture is composed of different substances
that are not chemically bonded, but simply
mixed together.
 Mixtures cannot be represented by a
chemical formula.
 Properties of mixtures can vary since
proportions can vary.
 Homogeneous Mixture:
a mixture of compounds
or elements in which all
regions are identical in
composition and
properties.
 Examples?
 Includes solutions, colloids, and alloys:
▪ Solutions: homogeneous mixtures in which all particles are
dissolved. Solutions are usually transparent.
▪ Vinegar, Kool-aid, tea
▪ Colloids: homogeneous mixtures in which larger particles
do not separate out from the mixture. Light is usually
scattered when passing through.
▪ Milk, paint, smoke
▪ Alloys: a mixture of two metals, or a metal and
a non-metal.
▪ Can also be heterogeneous!
▪ Examples: Brass = copper + zinc
Steel = iron + carbon
 Heterogeneous Mixture: a
mixture of compounds or
elements in which separate
regions are noticeable and
have differing compositions
and properties.
 Examples?
 Includes suspensions
▪ Suspension: mixture in which particles of one
substance is dispersed in the other. These
particles can be seen with the naked eye. Particles
will settle out of the suspension if left
undisturbed.
▪ Examples: sand in water, dust in the air

In the diagram below, which pictures do you think
represent mixtures and which represent pure substances?
Explain your answers. (The spheres represent atoms.)

Classify each type of matter as a pure substance or a
mixture. If it is a pure substance, classify it as an element
or a compound; if it is a mixture, classify it as
homogeneous or heterogeneous.
 (a) a lead weight
 (e) mercury in a thermometer
 (b) seawater
 (f) exhaled air
 (c) distilled water
 (g) chicken noodle soup
 (d) Italian salad dressing
 (h) Sugar