Group p-block

Although typical organic molecules, such as those of which all living things are composed, are constructed from only a few elements (usually C, H, O, N, S, and P and, on occasion, Cl, Br, I, and a few more), there are very many other elements that can be used as the basis for reagents, catalysts, and as components of synthetic intermediates. The metals will be discussed in the next chapter (48) but many main group (p block) elements are also important. These nonmetals bond covalently to carbon and some of their compounds are important in their own right. 

The term Zintl phase is applied to solids formed between either an alkali- or alkaline-earth metal and a main group p-block element from group 14, 15, or 16 in the periodic table. These phases are characterized by a network of homonuclear or heteronuclear polyatomic clusters (the Zintl ions), which carry a net negative charge, and that are neutralized by cations. Broader definitions of the Zintl phase are sometimes used. Group 13 elements have been included with the Zintl anions and an electropositive rare-earth element or transition element with a filled d shell (e.g. Cu) or empty d shell (e.g. Ti) has replaced the alkali- or alkaline-earth element in some reports. Although the bonding between the Zintl ions and the cations in the Zintl phases is markedly polar, by our earlier definition those compounds formed between the alkali- or alkaline-earth metals with the heavier anions (i.e. Sn, Pb, Bi) can be considered intermetallic phases. 

This chapter will show that only atoms with partially filled shells (i.e. atoms with unpaired electrons) can possess a net magnetic moment in the absence of an external field. Since main group p block) elements have atoms with filled d subshells and tend to form compounds with other p-block elements that result in filled p subshells in accordance with the octet rule, the vast majority of magnetic materials have historically contained transition metal atoms with partially filled d subshells. Nevertheless, some pure organic compounds with free radicals have been found to exhibit ferromagnetic intermolecular interactions, albeit at very low temperamres (several Kelvins). 

The compounds involved in these two types of reactions which will be surveyed in the following chapters are the higher-valent derivatives of the main-group p-block elements which include ... 

This book is intended to give to the synthetic chemist a useful introduction to the various facets of the chemistry which can be performed by reactions explained by this still insufficiently recognized mechanism in the chemistry of main-group p-block elements. 

Most donor atoms in ligands are members of the main group (p block) of the Periodic Table. Of these, common simple ligands you are likely to meet will be the following ... 

For main-group, p-block metals, remove np electrons before ns electrons. 

Design of self-adapting N-heteroaromatic-substituted claw ligands as E /M" " (E = p-block element, M = main group metal)chargedspacers 97CB1365. 

The inert-pair effect is the tendency to form ions two units lower in charge than expected from the group number it is most pronounced for heavy elements in the p block. 

Elements at the right of the p block have characteristically high electron affinities they tend to gain electrons to complete closed shells. Except for the metalloids tellurium and polonium, the members of Groups 16/VI and 17/VII are nonmetals (Fig. 1.62). They typically form molecular compounds with one another. They react with metals to form the anions in ionic compounds, and hence many of the minerals that surround us, such as limestone and granite, contain anions formed from non-metals, such as S2-, CO,2-, and S042-. Much of the metals industry is concerned with the problem of extracting metals from their combinations with nonmetals. 

All d-block elements are metals (Fig. 1.63). Their properties are transitional between the s- and the p-block elements, which (with the exception of the members of Group 12) accounts for their alternative name, the transition metals. Because transition metals in the same period differ mainly in the number of /-electrons, and these electrons are in inner shells, their properties are very similar. 

FIGURE 2.19 The dissociation energies for bonds between hydrogen and the p-block elements. The bond strengths decrease down each group as the atoms increase in size. 

FIGURE 5.8 The boiling points of most of the molecular hydrides of the p-block elements show a smooth increase with molar mass in each group. However, three compounds—ammonia, water, and hydrogen fluoride are strikingly out of line. 

Group 13/III is the first group of the p block. Its members have an ns np1 electron configuration (Table 14.5), and so we expect a maximum oxidation number of +3. The oxidation numbers of B and A1 are +3 in almost all their compounds. However, the heavier elements in the group are more likely to keep their s-electrons (the inert-pair effect, Section 1.19) so the oxidation number +1 becomes increasingly important down the group, and thallium(I) compounds are as common as... 

In the next breath you take, almost all the atoms you inhale will be of elements in the final four groups of the periodic table. Except for the gases containing carbon and hydrogen, air is made up almost entirely of elements from this part of the p block, some as elements and some as compounds. The p-block elements are present in most of the compounds necessary for life and are used to create fascinating and useful modern materials, such as superconductors, plasma screens, and high-performance nanodevices. 

The elements in Groups 3 through 11 are called the transition metals because they represent a transition from the highly reactive metals of the s block to the much less reactive metals of Group 12 and the p block (Fig. 16.1). Note that the transition metals do not extend all the way across the d block the Group 12 elements (zinc, cadmium, and mercury) are not normally considered to be transition elements. Because their d-orbitals are full, the Group 12 elements have properties that are more like those of main-group metals than those of transition metals. Just after... 

For a review of sulfur-Containing neighboring groups, see Block, E. Reactions of Organosulfur Compounds, Academic Press NY, 1978, p. 141. 

Lithium has been alloyed with gaUium and small amounts of valence-electron poorer elements Cu, Ag, Zn and Cd. like the early p-block elements (especially group 13), these elements are icosogen, a term which was coined by King for elements that can form icosahedron-based clusters [24]. In these combinations, the valence electron concentrations are reduced to such a degree that low-coordinated Ga atoms are no longer present, and icosahedral clustering prevails [25]. Periodic 3-D networks are formed from an icosahedron kernel and the icosahedral symmetry is extended within the boundary of a few shells. 

Germanium is element 32. Consult Figure 8 to determine that Ge is in Group 14, row 4 of the p block ... 

From the periodic table, we see that sulfur has 16 electrons and is in the p block. Group 16. To build the ground-state configuration, apply the normal filling rales and then apply Hund s rule if needed. 

All elements except those in the p block are metals. Group 15, however, is part of the p block, within which elements display all forms of elemental behavior. To decide the classifications of these elements, we must examine this group relative to the diagonal arrangement of the metalloids ... 

The transition metals lie in the d block, at the center of the periodic table, between the s-block metals and the elements in the p block, as Figure 20-1 shows. As we describe in Chapter 8, most transition metal atoms in the gas phase have valence electron configurations of, where x is the group number of the metal. Titanium, for... 

The chemistry of the transition metals is determined in part by their atomic ionization energies. Metals of the 3d and 4d series show a gradual increase in ionization energy with atomic number (Z), whereas the trend for the 5d series is more pronounced (Figure 20-3). First ionization energies for transition metals in the 3d and 4d series are between 650 and 750 kJ/mol, somewhat higher than the values for Group 2 alkaline earth metals but lower than the typical values for nonmetals in the p block. 

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