Atoms - DOE-HDBK-1109-97_reaffirmed20070046

DOE-HDBK-1109-97

Radiological Safety Training for Radiation-Producing (X-Ray) Devices

Instructor's Guide

Lesson Plan

Instructor's Notes

ATOMS

Objective 1

The atom, the basic unit of matter, is made up of three

primary particles: protons, neutrons, and electrons.

Protons and neutrons are found in the nucleus of the

atom; electrons are found orbiting the nucleus. Protons

have a positive charge; neutrons are neutral; electrons

have a negative charge. The configuration of electron

shells and the number of electrons in the shells

determine the chemical properties of atoms.

IONIZATION

An atom usually has a number of electrons equal to the

number of protons in its nucleus so that the atom is

electrically neutral. A charged atom, called an ion, can

have a positive or negative charge. Free electrons also

are called ions. An ion is formed when ionizing

radiation interacts with an orbiting electron and causes

it to be ejected from its orbit, a process called

ionization. This leaves a positively charged atom (or

molecule) and a free electron.

RADIATION

Radiation as used here means alpha particles, beta

Objective 1

particles, gamma rays, X-rays, neutrons, high-speed

electrons, high-speed protons, and other particles

capable of producing ions. Radiation with enough

energy to cause ionization is referred to as ionizing

radiation. Radiation that lacks the energy to cause

ionization is referred to as non-ionizing radiation.