Name
Matter, Atoms, Molecules,
and Elements
by Cindy Grigg
Answer the following questions BEFORE you read this book. It is
okay if you do not know as much as you thought. Do the best you
can!
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Look at this picture. What do you see? Students, a
book, a pencil, a window. What are these things
made of?
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Books are made of paper, glue, and ink. The pencil
is made of wood, graphite, metal, and an eraser.
Windows are made of glass. Students are made of
living cells, tissues, and organs.
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Matter, Atoms, Molecules, and Elements
This clump of matter in space is forming new
stars.
Each of the objects in the first picture is very
different from the others. Yet all the objects
are alike in some ways. All these things are
matter.
Matter is anything that takes up space and
has mass. Matter is the "stuff" that
everything in the universe is made of. Mass
is the amount of matter, or stuff, that
something is made of.
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Matter, Atoms, Molecules, and Elements
Volumes of cubes can be found by
multiplying the measurement of their length,
width, and height.
These things all take up space. The amount
of space they take up - their volume - can be
measured. Their mass can be measured, too.
This spring scale is one tool that can be used
to find the mass of an object.
In the kitchen, we use a measuring cup to
find the volume of liquids. This measuring
cup shows volume in three different units:
cups, fluid ounces, and milliliters.
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Matter, Atoms, Molecules, and Elements
Elements are made of only one kind of atom.
Elements are called "pure" substances.
All matter is made of atoms. Atoms are the
smallest pieces of an element that still have
the properties of that element.
For instance, you can take a piece of
aluminum and cut it into tiny little pieces,
and each piece is still a shiny, lightweight
metal. If you could cut that aluminum into
pieces that are too small to see with your
eyes or even with a good microscope, it
would still be aluminum.
There are only about 120 different elements. The
periodic table is a visual display showing the
elements. Aluminum is AL. Its atomic number is
13.
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Matter, Atoms, Molecules, and Elements
Atoms of different elements can combine to
make many other things. When two or more
atoms combine, they make a molecule. A
molecule is the smallest amount of a
substance that can exist.
Just as the 26 letters of our alphabet can
combine to make millions of words, the
elements can combine to make a huge
number of different kinds of substances.
A molecule can be made of the same kind of
atoms or different kinds. A molecule of
ozone is made of three oxygen atoms joined
together. A molecule of water (H2O) is
made of one oxygen atom bonded to two
atoms of hydrogen.
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Matter, Atoms, Molecules, and Elements
One way that atoms combine is to share
electrons. This is called covalent or chemical
bonding. When atoms join together and form
chemical bonds, or when chemical bonds are
broken between atoms, we call that a
chemical reaction.
How do atoms join together? You may
already know that atoms are made up of even
smaller bits of matter. The nucleus (or
center) of the atom holds the protons and
neutrons. Circling outside the nucleus are the
electrons.
Oxygen has six electrons in its outer shell. It
needs two more electrons to fill its outer
shell. Hydrogen has one electron. It needs
one more. When two hydrogen atoms share
their electrons with one oxygen atom, all
three atoms are happy!
Note: This is a simplfied picture of how an
atom might look.
(Note: The oxygen atom should be larger
than the two hydrogen atoms.)
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Matter, Atoms, Molecules, and Elements
Physical changes are changes in the physical
properties of a substance. They can be
changes in color, shape, or size. Physical
changes don't create new substances.
Physical changes in matter don't form or
break any chemical bonds. Water goes
through a physical change when it freezes
into ice or disappears into water vapor.
Adding or taking away heat causes physical
changes in water. Ice changes into liquid
water when it is heated, either on a stove top
or by the sun. With even more heat, liquid
water changes into water vapor. The water
in a mud puddle evaporates. It changes from
a liquid to a gas. It becomes water vapor in
the air.
What happens to the water in a mud puddle
after the sun comes out?
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Matter, Atoms, Molecules, and Elements
Solid butter melting on warm corn on the cob is a
physical change. Melted butter can become solid
again by cooling it.
Matter commonly exists on Earth in three
phases or states: solid, liquid, and gas.
Changes in states of matter are physical
changes. Physical changes can usually be
undone. If ice melts, we can undo that
physical change by simply freezing the water
again.
Butter, water, molecules, and even elements can
change from one state to another without changing
their atoms. Iron, an element that is usually a solid,
can be heated and melted into a liquid. It is made of
only iron atoms in both the solid and liquid states.
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Matter, Atoms, Molecules, and Elements
Water is H2O -- made of one oxygen atom
bonded to two atoms of hydrogen- whether it
is solid ice, liquid water, or gaseous water
vapor in the air. It can easily change from
one state of matter to another, but its
chemical state remains the same.
Lucky for us, matter can change states. It
wouldn't be much fun if water was always in
its solid state, would it? Imagine breathing
air that had chunks of ice instead of water
vapor in it! Imagine chunks of ice falling
from the sky instead of rain. Imagine oceans
and swimming pools filled with ice instead
of water. Lucky for us, all matter is not alike.
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Matter, Atoms, Molecules, and Elements
atoms - the smallest pieces of elements
covalent or chemical bonding when two or
more atoms combine by sharing electrons
electron- a particle of an atom that circles
outside the nucleus
elements - pure substances made up of only
one type of atom
mass - the amount of matter something
contains
matter - anything that takes up space and
has mass; matter makes up everything in the
universe
molecule - the smallest amount of a
substance that can exist; made of two or
more atoms
On Earth, most matter exists in three
different states - solid, liquid, and gas. The
stars are made of plasma, a fourth state of
matter. Matter has mass and volume, and
these can be measured. Look around you.
Everything you see is made of matter - even
the stars in the sky at night. Matter is made
of atoms. Atoms of only 120 different
elements can combine to make many
substances.
nucleus - the center of an atom, containing
the proton(s) and neutron(s)
neutron - a particle of an atom, found in the
nucleus
proton- a particle of an atom, found in the
nucleus
physical changes changes in the physical
properties of a substance, such as size, color,
shape, or state of matter
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Matter, Atoms, Molecules, and Elements
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