Lesson 1/Learning Event 1
MATTER AND THE ATOM
The mystery of electrification and the positive and negative charges was finally solved by studying
the construction of matter. "Matter" is any substance that has weight and occupies space.
Examples of matter are the air we breathe, water, cars, clothing, and so forth. To give you an idea
of what electricity really is, so that you will be able to predict its action in automotive electrical
circuits, we need to take a brief look at the construction of matter.
Imagine that you could take some form of matter, such as a rock, and break it down into the
smallest particles that it can exist in and still be the original substance that you started with. These
tiny particles are known as molecules.
Actually, you would not be able to do this, for as you continued to crush the rock you would finally
end up with particles of dust, and just one of the small dust particles would contain thousands of
Scientists have discovered that any molecule contains one or more building blocks known as atoms.
Each atom is an element. There are about 100 different kinds of atoms or elements. Some are
metal, such as copper, iron, and gold. Others are nonmetallic, such as oxygen, hydrogen, and
sulfur. While an element by itself is matter, different kinds of matter are formed by mixing
elements. When two or more elements are mixed, we get matter that is known as a compound.
For instance, a molecule of water is formed when two hydrogen atoms are joined with one oxygen
atom. Therefore, water is a compound.
The secret of electrification was not discovered until scientists finally discovered that atoms are
made up of three smaller particles. These particles are electrons, protons, and neutrons. The
protons have a positive charge, electrons have a negative charge, and neutrons are neutral (have no
charge). Figure 1 shows what we believe the atom looks like.