An Introduction to the Periodic Table

Na i usually called the sodium ion rather than the sodium cation. Also Cl is called the chloride ion rather than the chloride anion, in general, when a specific ion is referred to, the word ion rather than cation or anion is used. 

With one electron stripped oflf, the sodium, with its 11 protons and only 10 electrons, now has a net 1+ charge—it has become a positive ion. A positive ion is called a cation. The sodium ion is written as Na+, and the process can be represented in shorthand form as 

Because anions and cations have opposite charges, they attract each other. This force of attraction between oppositely charged ions is called ionic bonding. As illustrated in Fig. 2.17, sodium metal and chlorine gas (a green gas composed of CI2 molecules) react to form solid sodium chloride, which contains many Na and CD ions packed together and forms the beautiful colorless cubic crystals. 

A solid consisting of oppositely charged ions is called an ionic solid. Ionic solids can consist of simple ions, as in sodium chloride, or of polyatomic (many atom) ions, as in ammonium nitrate (NH4NO3), which contains ammonium ions (NH4+) and nitrate ions (NOb ). The ball-and-stick models of these ions are shown in Fig. 2.18. 

In a room where chemistry is taught or practiced, a chart called the periodic table is almost certain to be found hanging on the waU. This chart shows aU the known elements and gives a good deal of information about each. As our study of chemistry progresses, the usefulness of the periodic table will become more obvious. This section will simply introduce it to you. 

A simple version of the periodic table is shown in Fig. 2.21. The letters given in the boxes are the symbols for the elements, and the number shown above each symbol is the atomic number (number of protons) for that element. Most of the elements are metals. Metals have characteristic physical properties such as efficient conduction of heat and electricity, malleability (they can be hammered into thin sheets), ductility (they can be pulled into wires), and (often) a lustrous appearance. Chemically, metal atoms tend to lose electrons to form positive ions. For example, copper is a typical metal. It is lustrous (although it tarnishes readily) it is an excellent conductor of electricity (it is widely used in electrical wires) and it is readily formed into various shapes such as pipes for water systems. Copper is also found in many salts, such as the beautiful blue copper sulfate, in which copper is present as Cu2+ ions. Copper is a member of the transition metals—the metals shown in the center of the periodic table. 

The relatively few nonmetals appear in the upper right-hand corner of the table (to the right of the heavy line in Fig. 2.21), except hydrogen, a non-metal that is grouped with the metals. The nonmetals typically lack the physical properties that characterize the metals. Chemically, they tend to gain electrons to form anions in reactions with metals. Nonmetals often bond to each other by forming covalent bonds. For example, chlorine is a typical 

Samples of the alkali metals lithium, sodium, and potassium. 

The periodic table continues to expand as new elements are synthesized in particle accelerators. The element 114 has been added recently. 

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A simplified version of the periodic table is shown in Fig. 2.19. The letters in the boxes are the symbols for the elements these abbreviations are based on the current element names or the original names (see Table 2.2). The number shown above each 

Amazingly, a team of chemists from the Lawrence Berkeley National Laboratory in California, the Paul Scherrer Institute and the University of Bern in Switzerland, and the Institute of Nuclear Chemistry in Germany have done experiments to characterize the chemical behavior of hassium. For example, they have observed that hassium atoms react with oxygen to form a hassium oxide compound of the type expected from its position on the periodic table. The team has also measured other properties of hassium, including the energy released as it undergoes nuclear decay to another atom. 

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Elementary chemical concepts and an introduction to the periodic table are clearly explained in the early chapters of ... 

This introduction to the periodic table only touches the surface of its usefulness. In the next section, you will discover how an element s electron configuration, which you learned about in Chapter 5, is related to its position on the periodic table. 

Increased emphasis on atomic structure as the foundation of chemistry is achieved hy moving the atomic structure chapter to an earlier position, Chapter 4. That chapter includes an early, brief introduction to the periodic table. The key concept of chemical periodicity is then elaborated in more detail in Chapter 5. Instructors that wish to use an atoms first approach can easily start with Chapters 4 and 5, then return to stoichiometry concepts in Chapters 2 and 3. Because much of chemistry involves chemical reactions, we have introduced chemical reactions in a simplified, systematic way early in the text (Chapter 6). This placement allows us to build solidly on the ideas of atomic structure and chemical periodicity from the preceding two chapters. 

So I knew I would not be able to resist the lure of writing about the elements. But I began to see also that an introduction to the elements need not after all become a tour of the Periodic Table—which anyway others have conducted before me, and more skilfully or more exhaustively than I would be able to manage. The story of the elements is the story of our relationship with matter, something that predates any notion of the Periodic Table. Intimacy with matter does not depend on a detailed knowledge of silicon, phosphorus, and molybdenum it flows from the pleasurable density of a silver ingot, the cool sweetness of water, the smoothness of polished jade. That is the source of the fundamental question what is the world made from ... 

All the types of interatomic binding force to which we have referred above are primarily electronic in nature, and the differences between them arise from differences in the electronic structures of the particles concerned. In order that we may be able to understand the origin of these forces and to predict the types of force likely to operate in any particular structure it is therefore necessary that we should have a clear picture of the extranuclear electron distribution in the atoms of the elements, and of the way in which this distribution changes as we pass from one element to another in the Periodic Table. The rest of this chapter is accordingly devoted to a discussion of this topic and will serve as an introduction to the remaining four chapters of Part I, in which the different types of interatomic binding force are considered individually. 

The other chemist associated with the introduction of the periodic table was Lothar Meyer. In 1864, after his conversion to the new system of atomic weights by Cannizzaro, he published an important book. Die modernen Theorien der Chemie, which was influential in bringing about acceptance of the new system. The book contained a table of the elements arranged horizontally in terms of increasing atomic weight, and showed that similar elements fell in vertical columns. However, some elements were omitted, and like his contemporaries Lothar Meyer concentrated more on the differences between atomic weights of similar elements than on the principle of periodicity. 

FIGURE 5.11 An outline of the periodic table showing the relative sizes of atoms in the s-block and p-block. Notice the trend to smaller atom as one goes left to right and from bottom to top. The relative size of the cadmium atom is also indicated in order to compare it with the indium (In) atom, as discussed in the text. (From Kenkel, J., Kelter, P., and Hage, D., Chemistry An Industry-Based Introduction with CD-ROM, CRC Press, Boca Raton, FL, 2001. With Permission.)... 

H. A. Bent, F. Weinhold, News from the Periodic Table An Introduction to Periodicity Symbols, Tables, and Models for Higher-Order Valency and Donor—Acceptor Kinships, Journal of Chemical Education, 84 1145, 2007. 

This book contains key articles by Eric Sc erri, the leading authority on the history and philosophy of the periodic table of the elements and the author of a best-selling book on the subject. The articles explore a range of topics such as the historical evolution of the periodic system as well as its philosophical status and its relationship to modern quan um physics. This volume contains some in-depth research papers from journals in history and philosophy of science, as well as quantum chemistry. Other articles are from more accessible magazines like American Scientist. The author has also provided an extensive new introduction in orck rto integrate this work covering a pc riocl of two decades.This must-have publication is completely unique as there is nothing of this form currently available on the market. 

The halogens, the elements from Group 17 of the periodic table, provide an introduction to intermolecular forces. These elements exist as diatomic molecules F2, CI2, Bf2, and I2. The bonding patterns of the four halogens are identical. Each molecule contains two atoms held together by a single covalent bond that can be described by end-on overlap of valence p orbitals. 

This chapter describes typical aspects of the alloying behaviour of the different metals, with reference to the general topics previously discussed. The metals will be considered according to their order in the Periodic Table and to their reactivity towards the other elements. The Pettifor scale and the so-called Mendeleev number have been used in previous chapters as an introduction to some aspects of the alloying systematics. 

What is needed now (1913) is an answer to the question what is an element Up to this time elements had been characterized by their respective masses. But now different masses (isotopes) all correspond to the same element. As already noted, Mendeleev had assembled the elements into a table by writing down the elements in order of increasing mass and had found, by making the table two dimensional through the introduction of rows and columns, that he was able to construct the table so that elements in given columns had similar properties. The similarities included physical properties as well as chemical properties. The table was therefore called a periodic table (there was periodicity). However, Mendeleev noted immediately that, in order to make his table work , he needed to introduce blank spaces for missing elements. This was fine because it led to the prediction of new elements which were later actually found. However, there were also places in the table where he had to reverse the ordering demanded by the masses in order to obtain periodicity (e.g. Co and Ni). 

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