Table 1-1 Basic Particles

DOE-HDBK-1130-98

Module 1: Radiological Fundamentals

Instructor's Notes

Electrons

1) Electrons are in orbit around the nucleus of an atom.

2) Electrons have a negative electrical charge.

3) This negative charge is equal in magnitude to the proton's

positive charge.

Table 1 -1

Basic Particles

3 Basic

Location

Charge

Comments

Particles

Protons

Nucleus

Number of protons

(positive)

determines the element. If

the number of protons

changes, the element

changes.

Neutrons

Nucleus

Atoms of the same element

Charge

have the same number of

protons, but can have a

different number of

neutrons. This is called an

isotope.

Electrons

Orbit

This negative charge is

nucleus

(negative)

equal in magnitude to the

proton's positive charge.

2. Stable and unstable atoms

Only certain combinations of neutrons and protons result in

stable atoms.

a. If there are too many or too few neutrons for a given

number of protons, the nucleus will not be stable.

b. 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.