Table 1-1 Basic Particles - hdbk1130cn20053

DOE-HDBK-1130-98

Module 1: Radiological Fundamentals

Instructor's Notes

Electrons

Electrons are in orbit around the nucleus of an

atom.

Electrons have a negative electrical charge.

This negative charge is equal in magnitude to the

proton's positive charge.

Table 1-1

Basic Particles

3 Basic

Particles

Location

Charge

Comments

Protons

Nucleus

+ (positive)

Number of protons determines the

element. If the number of protons

changes, the element changes.

Neutrons

Nucleus

No Charge

Atoms of the same element have the

same number of protons, but can

have a different number of neutrons.

This is called an isotope.

Electrons

Orbit

- (negative)

This negative charge is equal in

nucleus

magnitude to the proton's positive

charge.

Stable and unstable atoms

Only certain combinations of neutrons and protons result in

stable 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 radioactive atoms.