Description of the Periodic Table

Solution. With the atomic mass 120 assigned to uranium by Berzelius the atoms of uranium would have only half the mass assigned to them by Mendelyeev, and accordingly Mendelyeev s formula UjOg would become UgOg or, in simplest form, U3O4. Similarly, Armstrong s value 180 (three quarters of 240) leads to the formula UO2. 

The horizontal rows of the periodic table consist of a very short period (containing hydrogen and helium, atomic numbers 1 and 2), two short periods of 8 elements each, two long periods of 18 elements each, a very long period of 32 elements, and an incomplete period. 

The density of the elements in the solid slate, in g cm The symbols of the elements at high and low points of ihe jagged curve are shown. 

The vertical coluiniis of the periodic table, with connections between the short and long periods as shown, are the groups of chemical elements. Elements in the same group may be called congeners these elements have closely related physical and chemical properties. 

The groups 1, II, and III are considered to include the elements in corresponding places at the left side of all the periods in Table 5-1, and IV, V, VI, and VII the elements at the right side. The central elements of the long periods, called the transition elements, have properties differing from those of the elements of the short periods these elements are discussed separately, as groups IVa, Va, Via, Vila, VIII (which, for historical reasons, includes three elements in each long period), Ib, Ilb, and IIIb. 

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Atkins, P.W. (1997). ThePeriodicKingdom A Journey into the Land of the Chemical Elements, Basic Books, New York. A metaphorical description of the periodic table of chemical elements. Appropriate for any level of scientific background. 

This book provides a general overview of chemistry with sections on all the main areas you ll find in a chemistry classroom or individual study of the subject. The basics are covered to familiarize you with the terms and concepts most common in experimental sciences like chemistry. There is a Periodic Table printed on the inside cover of this book, as well as in Chapter 4 to use as a reference. Additionally, I have listed a couple of Internet sites on the Periodic Table that have a lot of good information. The Periodic Table is the single most useful tool in the study of chemistry beside the pencil. The complete description of the Periodic Table and its uses is described in Chapter 4. 

Mendeleev s periodic table consisted of 8 groups, but most modern periodic tables are arranged in 18 groups of elements. Let us briefly review the description of the periodic table given in Section 2-6. 

It can now be seen that there is a direct and simple correspondence between this description of electronic structure and the form of the periodic table. Hydrogen, with 1 proton and 1 electron, is the first element, and, in the ground state (i.e. the state of lowest energy) it has the electronic configuration ls with zero orbital angular momentum. Helium, 2 = 2, has the configuration Is, and this completes the first period since no... 

Paper four first appeared in the Journal of Chemical Education and aimed to highlight one of the important ways in which the periodic table is not fully explained by quantum mechanics. The orbital model and the four quantum number description of electrons, as described earlier, is generally taken as the explanation of the periodic table but there is an important and often neglected limitation in this explanation. This is the fact that the possible combinations of four quantum numbers, which are strictly deduced from the theory, explain the closing of electron shells but not the closing of the periods. That is to say the deductive explanation only shows why successive electron shells can contain 2, 8, 18 and 32 electrons respectively. 

We have described the layout of the periodic table in terms of the orbital descriptions of the various elements. As our Box describes, the periodic table was first proposed well before quantum theory was developed, when the only guidelines available were patterns of chemical and physical behavior. 

The description of the first 10 electrons in the configuration of aluminum is identical to that of neon, so we can represent that portion as [Ne]. With this notation, the configuration of A1 becomes [Ne] 3 5" 3 p The element at the end of each row of the periodic table has a noble gas configuration. These configurations can be written in the following shorthand notation ... 

Ion formation is only one pattern of chemical behavior. Many other chemical trends can be traced ultimately to valence electron configurations, but we need the description of chemical bonding that appears in Chapters 9 and 10 to explain such periodic properties. Nevertheless, we can relate important patterns in chemical behavior to the ability of some elements to form ions. One example is the subdivision of the periodic table into metals, nonmetals, and metalloids, first introduced in Chapter 1. 

Elements beyond the second row of the periodic table can form bonds to more than four ligands and can be associated with more than an octet of electrons. These features are possible for two reasons. First, elements with > 2 have atomic radii that are large enough to bond to 5, 6, or even more ligands. Second, elements with > 2 have d orbitals whose energies are close to the energies of the valence p orbitals. An orbital overlap description of the bonding in these species relies on the participation of d orbitals of the inner atom. 

There are also molecules that are exceptions to the octet rule because one of the atoms has fewer, rather than more than, eight electrons in its valence shell in the Lewis structure (Figure 1.19). These molecules are formed by the elements on the left-hand side of the periodic table that have only one, two, or three electrons in their valence shells and cannot therefore attain an octet by using each of their electrons to form a covalent bond. The molecules LiF, BeCl2, BF3, and AIC13 would be examples. However, as we have seen and as we will discuss in detail in Chapters 8 and 9, these molecules are predominately ionic. In terms of a fully ionic model, each atom has a completed shell, and the anions obey the octet rule. Only if they are regarded as covalent can they be considered to be exceptions to the octet rule. Covalent descriptions of the bonding in BF3 and related molecules have therefore... 

Consequently, it must be emphasized that precautions have to be taken with the conventional rough description of molecules based on the chemical bond pattern. In a molecule that contains at least two atoms which do not belong to the first row of the periodic table, the energy and all the monoelectronic properties are literally spread out over the whole molecule. Obviously, the concept of chemical bond, based as it is on the principle of topological proximity, is inadequate on its own for a correct description of the chemical and physical behavior of such a molecule. 

Another chapter (Chapter 4) is entitled Intermetallic reactivity trends in the Periodic Table . The Periodic Table, indeed (or Periodic Law or Periodic System of Chemical Elements), is acknowledged to play an indispensable role in several different sciences. Especially in inorganic chemistry it represents a fundamental classifi-catory scheme and a means of systematizing data with a clear predictive power. Inorganic chemists have traditionally made considerable use of the Periodic Table to understand the chemistry of the different elements. With a few exceptions (as detailed in the same chapter), metallurgists and intermetallic chemists have made little use of this Table to understand and describe the properties of metals and alloys we believe, however, that it may be a useful tool also in the systematics of descriptive intermetallic chemistry (as exemplified in the subsequent chapter (Chapter 5)). In several paragraphs of Chapter 4, therefore, different aspects of the Periodic Table and of its characteristic trends are summarized. 

Just as it is effective in the other fields of inorganic descriptive chemistry, the Periodic Table is an essential reference point in intermetallic chemistry too. The general alloying characteristics of the different metals, their reactivity towards the other metals, the variety of their intermetallic derivatives usually are very complex and cannot be easily explained and rationalized on the basis of a few concepts and data. Nevertheless a sound first criterion for a description and classification of the intermetallic behaviour of the various metals lies in their position in the Periodic Table. 

On the basis of the Periodic Table, topics of intermetallic systematics will be presented in the next chapter. In the present chapter the Periodic Table will be revisited and its structure and subdivisions summarized. In relation also to some concepts previously presented, such as electronegativity, Mendeleev number, etc. described in Chapter 2, typical property trends along the Table will be shown. Strictly related concepts, such as Periodic Table group number, average group number and valence-electron number will be considered and used in the description and classification of intermetallic phase families. 

This description of the electronic structure can be related to the form of the Periodic Table. Hydrogen with a nucleus having a charge +1 and only one electron... 

Comments on some trends and on the Divides in the Periodic Table. It is clear that, on the basis also of the atomic structure of the different elements, the subdivision of the Periodic Table in blocks and the consideration of its groups and periods are fundamental reference tools in the description and classification of the properties and behaviour of the elements and in the definition of typical trends in such characteristics. Well-known chemical examples are the valence-electron numbers, the oxidation states, the general reactivity, etc. As far as the intermetallic reactivity is concerned, these aspects will be examined in detail in the various paragraphs of Chapter 5 where, for the different groups of metals, the alloying behaviour, its trend and periodicity will be discussed. A few more particular trends and classification criteria, which are especially relevant in specific positions of the Periodic Table, will be summarized here. 

Abstract A brief introduction deals with the time period from Dalton to the discovery of isotopes by Soddy and Fajans in the early twentieth century which was soon followed by the invention of the mass spectrograph (1922). The next section covers the period from 1922 to the discovery of deuterium by Urey and his colleagues. It includes a discussion of isotope effects in spectroscopy, particularly band spectra of diatomic molecules, and also discusses the discovery of the important stable isotopes in the second row of the periodic table. It ends with the discovery of deuterium, probably the most popular isotope for isotope effect studies. The chapter ends with a short description of the apparatus of theory and experimentation available for isotope effect work at the time of the discovery of deuterium. 

In this section, you saw how the ideas of quantum mechanics led to a new, revolutionary atomic model—the quantum mechanical model of the atom. According to this model, electrons have both matter-like and wave-like properties. Their position and momentum cannot both be determined with certainty, so they must be described in terms of probabilities. An orbital represents a mathematical description of the volume of space in which an electron has a high probability of being found. You learned the first three quantum numbers that describe the size, energy, shape, and orientation of an orbital. In the next section, you will use quantum numbers to describe the total number of electrons in an atom and the energy levels in which they are most likely to be found in their ground state. You will also discover how the ideas of quantum mechanics explain the structure and organization of the periodic table. 

Although this chapter discusses compounds where the band picture of Fig. 7.3 holds, this picture breaks down for smaller transition metal atoms, especially those toward the end of the first row of the periodic table (Zaanen, Sawatsky and Allen, 1985). There, a localised description is more appropriate the d states remain atomic-like d orbitals, and the materials can be non-metallic even though the band picture indicates a partially... 

In supported metallic catalysts, the metals are usually from Groups VIII and VB of the Periodic Table. For highly dispersed metallic catalysts, the support or the carrier is usually a ceramic oxide (silica or alumina) or carbon with a high surface area, as described in chapter 2. Supported metallic catalysts can be prepared in a number of ways as described by Anderson (1975). A description of some of the methods used to prepare representative model (thin film) and practical (technological) powder systems follows. 

R. J. Puddephatt and P. K. Monaghan, The Periodic Table of the Elements, 2nd edn., Oxford University Press, Oxford, 1986. A concise description of the structure of the Periodic Table and a discussion of periodic trends of many physical and chemical properties of the elements. 

This chapter consists of a description of the structure of liquid water and the nature of ions in aqueous solution. The discussion is largely restricted to the interactions between monatomic ions with liquid water in which they become hydrated by acquiring a hydratiun sphere or shell-Additionally, a few diatomic and polyatomic anions are dealt with, including the important hydroxide ion. The hydration of ions derived from the s- and p-block elements of the Periodic Table, and the derivation of values of their enthalpies and entropies of liydralioii, are described in considerable detail. 

Calculations using the methods of non-relativistic quantum mechanics have now advanced to the point at which they can provide quantitative predictions of the structure and properties of atoms, their ions, molecules, and solids containing atoms from the first two rows of the Periodical Table. However, there is much evidence that relativistic effects grow in importance with the increase of atomic number, and the competition between relativistic and correlation effects dominates over the properties of materials from the first transition row onwards. This makes it obligatory to use methods based on relativistic quantum mechanics if one wishes to obtain even qualitatively realistic descriptions of the properties of systems containing heavy elements. Many of these dominate in materials being considered as new high-temperature superconductors. 

In fact, it is the only book in which you can find successive general non-relativistic and relativistic descriptions of the theory of energy spectra and transition probabilities in complex many-electron atoms and ions. The formulas and tables presented give the possibility, at least in principle, of calculating the energy spectra and electronic transitions of any multipolarity for any atom or ion of the Periodical Table. This book contains the bulk of new achievements in the non-relativistic and relativistic theory of an atom, especially as concerns the many-particle aspects of the non-relativistic and relativistic problem. It therefore complements books already available. 

In Chapter 1 it was noted that speciation may be defined as a description of species types (forms/phases) and concentrations. The descriptions of speciation found in this chapter will largely be viewed from this perspective and described in terms of comparative chemistries. The framework for this discussion will be the associations and groupings of the Periodic Table. For further descriptions of seawater chemistry, including sampling and analytical considerations, the reader is directed to the excellent reviews of Bruland (1983) and Donat and Bruland (1995). 

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