After
reading this section you will be able to do the following:
Define
the terms "strong force" and "binding energy."
Explain
what is meant by a stable atom and and an unstable atom.
How do atomic
particles interact?
There are forces within the atom that
account for the behavior of the protons, neutrons, and electrons.
Without these forces, an atom could not stay together. Recall
that protons have a positive charge, electrons a negative charge,
and neutrons are neutral. According to the laws of physics, like
charges repel each other and unlike charges attract each other.
So
what makes the protons stay together in an atom?
A force called
the strong force opposes and overcomes the force of repulsion between the protons and holds the nucleus
together. The energy associated with the strong force is called the binding energy.
The electrons are kept in orbit around the nucleus because there
is an electromagnetic field of attraction between the positive
charge of the protons and the negative charge of the electrons.
Does
the nucleus of an atom ever lose particles?
In some atoms, the binding
energy is great enough to hold the nucleus together. The
nucleus of this kind of atom is said to be stable. In some
atoms the binding energy is not strong enough to hold the
nucleus together, and the nuclei of these atoms are said to be
unstable. Unstable atoms will lose neutrons and protons
as they attempt to become stable.
Review:
Electromagnetic
fields cause like charges to repel each other and unlike
charges to attract each other.
The protons
stay together in the nucleus because the strong force
opposes and overcomes the forces of repulsion from the electromagnetic field.
Binding
energy is the energy that is associated with the strong
force, and this energy holds the nucleus together.
A stable
atom is an atom that has enough binding energy to hold the
nucleus together permanently.
An unstable
atom does not have enough binding energy to hold the nucleus
together permanently and is called a radioactive atom
