BASICS OF RADIATION AND RADIOACTIVITY- PART ONE
ATOMIC MODEL
Protons (positively charged)
Neutrons (uncharged)
Atoms consist of positively charged nuclei and one or more negative electrons. The nucleus of an atom contains one or more positively charged protons and uncharged neutrons. Protons and neutrons are approximately the same size, electrons are much smaller.
The number of protons defines the element. Hydrogen atoms all contain one proton while radon atoms have 86 protons. The number of protons is referred to as the "atomic number" The combination of the number of neutrons and protons in the atomic nucleus is called the "mass number"
Copyright 2000, Great Lakes Center for Occupational & Environmental Safety & Health, School of Public Health, University of Illinois at Chicago