Chemical Agents of Opportunity for Terrorism: TICs & TIMs

Chemical Agents of Opportunity for Terrorism
Training Support Package
Participant Guide
Slide 16
In order to understand radiation, we need to briefly review the structure of matter. An
atom consists of a nucleus, made up of protons (positively charged) and neutrons (no
charge, neutral), surrounded by a cloud of rapidly moving electrons (negatively charged).
Electrons are tiny compared to protons and neutrons, which are approximately the same
size.
The four basic types of ionizing radiation include:
alpha particles are essentially helium nuclei (2 protons and 2 neutrons), ejected from the
nucleus of a larger atom and moving with high energy. Following an alpha emission, the
atom transforms from one element into another (since an element is defined by its
number of protons, the atomic number).
A beta particle is an electron that is ejected from the electron cloud around the nucleus.
Gamma radiation is not particulate, but rather electromagnetic rays that are emitted from
the nucleus. X-rays are similar to gamma rays, but have an origin outside the nucleus.
Neutrons are uncharged particles ejected from the nucleus.
Beta release, gamma ray, X-ray, or neutron release do not change the atom into another
element.
December 2008 Version 2.0 Page 379