Matter Is Made of Elements and Atoms
between matter and energy.
the major chemical elements in your body.
the parts of an atom.
and describe the uses of
h em istry
(KEM-is-tre) is the science of the
structure and interactions of matter and en-
ergy. Let’s take a closer look at the different
states of matter and energy and examine the
changes and interactions that each undergo.
Matter Is Different from Energy
is anything that occupies space and has mass.
Matter comes in three forms, or states:
has definite shape and
Examples of solids are bones and muscles.
liq u id
has definite volume but not shape.
Examples of liquids are blood plasma and urine.
has no definite shape or volume. An example
of a gas is air.
, such as the change of
state of water from a liquid to a
gas when it boils. As another ex-
ample, ice melts into liquid wa-
ter, but both forms are water; the
basic substance does not change.
Matter can also undergo
. For example, when
a nail rusts, the iron combines with oxygen to form iron
oxide (rust). When wood burns in a fire (
carbon-containing molecules in the wood combine with
oxygen in the air to form gaseous carbon dioxide and wa-
Unlike matter, energy has no mass and does not oc-
E n e rg y
is defined as the ability to do work.
Energy is usually classified as either kinetic energy or
K in e tic energy
is the energy of mo-
tion, such as moving your body or arms or
moving smaller pieces of matter, such as
atoms and molecules.
P o te n tia l energy
stored energy. For example, a book on a high
shelf has gravitational potential energy. If the book fell
off the shelf because of the constant vibration from your
roommate hitting the wall with a basketball, the book’s
downward motion would be kinetic energy. So, poten-
of space taken up by
A change in form that
matter can undergo
without altering its
change in matter that
alters its basic nature.
Matter and energy in a campfire • Figure 2.1
Cooking over a campfire shows many states of matter, energy, physical changes, and
6. Boiling is a physical
change that turns
liquid water into
steam, a gas.
3. The fire emits heat and light
energy. Energy heats the solid pot
and the liquid water in the pot.
2. Burning is a chemical
change that releases energy.
Which of the following represents a physical change?
a. Burning wood
c. Boiling water
b. Smoke from the fire
d. Light from the fire
4. Smoke from the fire
contains gases and
solid particles of ash.
5. Water in the
22 CHAPTER 2