The Main Group Elements

Mendeleev s 1869 Periodic Table (Top) and 1870 Table (bottom). Image from Edgar Fahs Smith Collection, University of Pennsylvania Library. 

Die nach der Grbsse des Atomgewichts geordneten Elemente zeigen eine stufenweise Abanderung in den Eigenschanen. 

Chemisch-analoge Elemente haben entweder ttbereinstimmende Atom-gewicbte (Pt, Ir, Os), oder letztere nehmen gleichviel zu (K. Bb, Cs). 

Das Anordnen nach den Atomgewichten entspricht der Werthi keit der Elemente und bis zu einem gewissen Grade der Verschiedenheit im chemischen Verhalten, z. B. Li, Be, B, C, N, 0, F. 

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V. Chvalovsky, in B. J. Aylett, ed., Organometallic derivatives of the Main Group Elements, Butterworths, London, 1975. 

Hydrogen combines with many elements to form binary hydrides MH (or M H ). All the main-group elements except the noble gases and perhaps indium and thallium form hydrides, as do all the lanthanoids and actinoids that have been studied. Hydrides are also formed by the more electropositive transition elements, notably Sc, Y, La, Ac Ti, Zr, Hf and to a lesser... 

E. Coates, M. L. H. Green and K. Wade, Organo-meiallh Compounds, Vol. 1. The Main Group Elements, 3rd edn Chap. It. Group II. pp. 71-121. Methuen. London. 1967... 

H. Hoffmann and M. Becke-Goehring, Topics in Phosphorus Chemistry 8, 193-271 (1976) J. G. Riess in A. H. Cowley (ed.), Rings, Clusters and Polymers of the Main Group Elements, ACS Symposium Series No. 232, 17-47 (1983). 

Hellwinkel, D. Penta- and.Hexaorganyl Derivatives of the Main Group Elements. 109, 1-63... 

The charges of ions formed by atoms of the main-group elements can be predicted by applying a simple principle ... 

The atomic radii of the main-group elements are shown at the top of Figure 6.13 (p. 153). Notice that, in general, atomic radii—... 

Atomic and ionic radii of the main-group elements. Negative ions are always larger than atoms of the same element, whereas positive ions are always smaller than atoms of the same element. ... 

The radii of cations and anions derived from atoms of the main-group elements are shown at the bottom of Figure 6.13. The trends referred to previously for atomic radii are dearly visible with ionic radius as well. Notice, for example, that ionic radius increases moving down a group in the periodic table. Moreover the radii of both cations (left) and anions (right) decrease from left to right across a period. 

Ionization energies of the main-group elements are listed in Figure 6.15. Notice that ionization energy—... 

These structures (without the circles) are referred to as Lewis structures. In writing Lewis structures, only the valence electrons written above are shown, because they are the ones that participate in covalent bonding. For the main-group elements, the only ones dealt with here, the number of valence electrons is equal to the last digit of the group number in the periodic table (Table 7.1). Notice that elements in a given main group all have the same number of valence electrons. This explains why such elements behave similarly when they react to form covalently bonded species. 

General surveys of advances in coordination chemistry appear in Annual Reports , The Royal Society of Chemistry, London, Section A. More specialized reports were published in the form of the Specialist Periodical Reports Inorganic Chemistry of the Transition Elements , The Chemical Society, London (Volumes 1-6), which reviewed the literature published between 1971 and 1976, and the Specialist Periodical Reports Inorganic Chemistry of the Main Group Elements , The Chemical Society, London (Volumes 1-5), which reviewed the literature published between 1971 and 1976. Both these series have now been discontinued. 

Phosphorus, arsenic and antimony complexes of the main group elements. W. Levason and C. A. McAuliffe, Coord. Chem. Rev., 1976,19,173-185 (88). 

Thio- and seleno-compounds of the main group elements — novel inorganic oligomers and polymers. B. Krebs, Angew. Chem., Int. Ed. Engl., 1983, 22,113-134 (252),... 

FIGURE 1.48 The ionic radii (in picometers) of the ions of the main-group elements. Note that cations are typically smaller than anions-in some cases, very much smaller. 

FIGURE 1.50 Hie first ionization energies of the main-group elements, in kilojoules per mole. In general, low values are found at the lower left of the table and high values are found at the upper right. 

The usefulness of the main-group elements in materials is related to their properties, which can be predicted from periodic trends. For example, an s-block element has a low ionization energy, which means that its outermost electrons can easily be lost. An s-block element is therefore likely to be a reactive metal with all the characteristics that the name metal implies (Table 1.4, Fig. 1.60). Because ionization energies are... 

Predict and explain trends in the properties and formulas of the main-group elements. 

The general structure of this chapter is the same as that of Chapter 14. We work systematically across the remainder of the main-group elements to highlight periodic trends, the production of the elements, and the properties and applications of the elements and their important compounds. 

Coates, C. E., Aylett, B., and Wade, K., "Organometallic Compounds, Vol. 1 The Main Group Elements, Methuen, London, 1978. 

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