Periodic Table: Trends in the Properties of the Elements
Published Online: 15 MAR 2006
Copyright © 2006 John Wiley & Sons, Ltd
Encyclopedia of Inorganic Chemistry
How to Cite
Wulfsberg, G. P. 2006. Periodic Table: Trends in the Properties of the Elements. Encyclopedia of Inorganic Chemistry. .
- Published Online: 15 MAR 2006
The article gives examples of trends in properties of the elements, their ions, and their compounds, which can usefully be examined from the perspective of the periodic table as a whole, rather than by looking at one group of elements (or even individual elements) at a time. The properties discussed are those of great interest not only to inorganic chemists but also to research workers in allied fields, such as the other branches of chemistry, medicinal chemistry, environmental science, agricultural and geochemistry, industrial chemistry and safety, metallurgy, materials science, and surface chemistry. These trends can be organized, explained, and predicted on the basis of a small set of parameters of the elements and their ions, most notably the sizes of the ions, their charges (or oxidation numbers), and the Pauling electronegativities of the elements. Trends are emphasized in acid–base reactivity, precipitation and solubility trends, coordination chemistry, oxidation–reduction chemistry, and physical properties of the elements and their compounds. Much acid–base and precipitation chemistry can be predicted after calculating the pKa values of cations and the pKb values of anions, or simply predicting to which of the six acidity and basicity categories an ion belongs. Generally very useful in coordination chemistry are the chelate and macrocyclic effects and the Hard–Soft Acid–Base (HSAB) Principle. Oxidation–reduction chemistry of the elements can be summarized graphically in the form of Pourbaix diagrams or by redox predominance diagrams where the pH is set at the standard pH value of zero. Among physical properties, perhaps the most important for applications in materials science is whether a compound that might be synthesized is a solid with an extended structure; methods are given for predicting this on the basis of the radius ratios of the cations and anions (at least formally) contained in the compound. One physical property, metallic conduction, is discussed in further detail. As an example of chemical properties, trends in the acidity and basicity of oxides of the elements are discussed.
- periodic trends;
- metallic properties;
- Pourbaix diagrams;
- coordination number;
- oxo anions;
- Slater's rules