The term GASEOUS RADIOACTIVE ELEMENT can be summarized by the word RADON, which is a chemical element with the symbol Rn and atomic number 86. It is a radioactive, colorless, odorless, tasteless noble gas that occurs naturally in minute quantities in the atmosphere. RADON is one of the densest substances that remains a gas under normal conditions. It is also the most radioactive element and is considered to be a health hazard due to its radioactivity.