Environmental Engineering Reference
Atoms are made up of particles called protons, neutrons, and electrons. This picture shows
a carbon atom.
Two—known as protons and neutrons —lie in the middle of
the atom, which is called the nucleus . (The plural of nucleus
is nuclei.) Electrons are the third type of particle. They ly
around the nucleus. Protons tend to push each other away.
This is because they all have what is called a positive electrical
charge. Neutrons are neutral. This means that they do not have
any charge at all. Electrons have a negative electrical charge.
What stops the nucleus from just lying apart? The answer
is energy. A huge amount of energy holds the nucleus together.
With certain kinds of atoms, people can make use of some
of this nuclear energy. Nuclear energy, for instance, is used to
make heat for producing electricity and for making powerful