A chemical element is represented in the periodic table by a chemical symbol, an atomic number and atomic mass. Elements are organized in increasing atomic numbers that obey a certain periodic law. Elements that are listed within a row have the same period while those that fall under a column belong to the same group, which is often given a special name.
Different methods are used in labeling various groups. One way is to number the groups from one to 18 all the way across the periodic table, from the left hand side to the right hand side. Group one elements are known as alkali metals while group two elements are called alkaline earths. Group 17 are referred to as the halogens while group 18 are designated as noble gases, otherwise known as inert gases.
Noble gases are characterized by their nonreactivity with other chemical elements. These gases include helium, argon, radon, krypton, neon and xenon. The reason why noble gases are chemically inert is because of a filled octet that contain eight valence electrons. A full octet signifies that an element is less likely to lose, gain or share electrons, hence, noble gases remain inert and do not readily form chemical bonds with other elements.Learn more about Atoms & Molecules