Ward's World + McGraw Hill's AccessScience

Ward's World+MGH Periodic Table

Issue link: https://wardsworld.wardsci.com/i/1420328

Contents of this Issue


Page 0 of 3

Periodic Table Article by: Kaner, Richard B. , Department of Chemistry and Biochemistry, University of Los Angeles, Los Angeles, California. Access to this content is available to Ward's World readers for free from McGraw Hill's AccessScience, an award-winning, digital STEM resource containing exclusive articles written by expert scientists and engineers; biographies of well-known scientific figures; science news, videos, and animations; and much, much more. Instructors can use AccessScience to guide students on their research project journeys, to help students understand scientific concepts, to support distance learning efforts, in flipped classroom approaches, and in countless other ways. Ward's World and AccessScience have partnered to offer educators a no-obligation, free trial subscription to AccessScience. Request your free trial today to discover how valuable AccessScience can be for you and your students! Get your free trial now. A list of chemical elements arranged along horizontal rows in increasing atomic number. It is organized such that the vertical columns consist of elements with remark- ably similar properties (see illustration). The first column, known as the alkali metals (albeit with hydrogen, a nonmetal on top), contains elements with just one outer (valence) electron. The last column has completely filled valence orbitals leading to chemically inert elements called the noble gases. The position of elements in the periodic table provides a powerful method of classifying not only the physical properties of elements but also their expected properties in molecules and solids. The periodic table dates back to around 1870 when the Russian chemist D. Mendeleev used the similarities in chemical reactivity attributed to different elements to group them according to increasing atomic mass. However, this left blank spaces that Mendeleev boldly predicted would be filled by elements that were then undiscovered. Not only did other scientists discover missing elements including scandium, gallium, and germanium, but remarkably these elements possessed properties similar to Mendeleev's predictions. Although the layout of the periodic table has changed over time with the addition of new elements, the essential information remains comparable to the original periodic table. + ward ' s science Content • Groups • Periods • Elements • Other properties Key Concepts • Originally developed by the Russian chemist D. Mendeleev, the periodic table lists every known chemical element in horizontal rows ("periods") by increasing atomic number. • Each cell in the periodic table contains a symbol representing the element and its atomic number. • Each column of the periodic table contains a family (group) of chemicals with the same number of valence electrons and, therefore, similar chemical properties. • The left side of the periodic table includes the alkali (group 1) and alkaline earth (group 2) metals, followed by the transition metals in the center. • The right side of the periodic table contains the nonmetals (except hydrogen), including halogens (group 17) and noble gases (group 18).

Articles in this issue

Links on this page

Archives of this issue

view archives of Ward's World + McGraw Hill's AccessScience - Ward's World+MGH Periodic Table