Book excerpt: In spite of their adjacency in the periodic table, halogens and nonmetals have very different properties. Halogens are among the most chemically reactive elements in the periodic table, exhibiting a diverse chemistry in terms of the large numbers of compounds they can form. On the other hand, noble gases are the least chemically reactive elements. In fact, before the 1960s, chemists referred to these elements as inert gases, because it was believed that they exhibited no chemistry whatsoever. Providing the basics of these elements, including their role in history and some of the important scientists involved in their discovery, this newly updated, full-color resource features up-to-date scientific understanding in a clear and accessible format. Halogens and Noble Gases, Second Edition examines the ways humans use halogens and noble gases and the resulting benefits and challenges to society, health, and the environment. Fluorine, chlorine, bromine, iodine, helium, and krypton are covered in this eBook, along with the fundamentals of chemistry and physics as well as possible future developments in halogen and noble gas science and its applications.