Number of protons determines the
element. If the number of protons
changes, the element changes.
Atoms of the same element have the
same number of protons, but can
have a different number of neutrons.
This is called an isotope.
This negative charge is equal in
magnitude to the proton's positive
Stable and unstable atoms
If there are too many or too few neutrons for a given number of protons, the nucleus
will not be stable.
The unstable atom will try to become stable by giving off excess energy. This energy is
in the form of particles or rays (radiation). These unstable atoms are known as
Charge of the atom
The number of electrons and protons determines the overall electrical charge of the atom.
The term "ion" is used to define atoms or groups of atoms that have a net positive or
negative electrical charge.
No charge (neutral)
If the number of electrons equals the number of protons, the atom is electrically neutral.
This atom does not have a net electrical charge.
Positive charge (+)
If there are more protons than electrons, the atom is positively charged.
Negative charge (-)
If there are more electrons than protons, the atom is negatively charged.