to the nucleus. This is, perhaps, an over-simplified description of the atom, but one which will have to suffice for our purposes. There are a few hundred different atoms and their difference is indicated by the number of neutrons (neutrally charged) and protons (positively charged) their nuclei. "marbles" in An element is defined as an atom with a given number of protons in its nucleus. Isotopes of an element have different numbers of neutrons in their individual nuclei, Two other qualities of atoms and their relation to radioactivity should be mentioned, energies, Atoms may emit different types of particles of different A second fact is that the number and arrangement of electrons determines the chemical factors of an element. While many are different, there can also be atoms with the same number of electrons and, consequently, the same number of positively-charged (protons) particles in the nucleus. Since they are the same in this respect, they are like chemical brothers. they can form the same larger units like molecules. There are five types of emitted energies mentioned in this report but only three will be used frequently. 1. Neutrons 2. X-rays 3. Gamma rays 4. Alpha particles 5. Beta particles Neutrons: The five are: These particles are emitted during the chain reaction which takes place during a nuclear explosion of an atom or hydrogen bomb. A neutron has about the same mass as a proton but is uncharged. It is highly penetrating in all materials except those of mass near that of its own.