Which of the following statements
correctly describes the forces that act on the particles in the nucleus of an
atom? (A) There are only attractive
forces on the particles. (B) There are only repulsive forces
on the particles. (C) There are no forces on the
particles. (D) There are attractive and
repulsive forces on the particles.
What forces act on the particles in
the nucleus of an atom? First of all, what particles are
there in the nucleus? Recall that there are three types
of subatomic particles in an atom. These are the proton, the electron,
and the neutron. Electrons are negatively charged
and are found around the nucleus, not within the nucleus. A nucleus is made of protons and
neutrons. Protons are positively charged. Neutrons are uncharged, or
It is essential to understand that
in a stable atom, protons and neutrons do not leave the nucleus of the atom. The protons and neutrons are held
together. It is also extremely important to
recall that same-sign charges repel each other. Protons are both positively charged
and so repel each other. Therefore, protons in a nucleus
must repel each other.
We see then that there must be
repulsive forces acting on protons in a nucleus. We have said though that the
particles in a nucleus are held together. The protons stay in the nucleus, so
a force must attract the protons to at least some parts of the nucleus. The force that holds protons in a
nucleus is called the strong nuclear force.
We see then that there must be both
attractive and repulsive forces in the nucleus. Option (D) is correct.