S-block metals

Why are s-block metals more reactive than p-block metals ... 

The ionic model, the description of bonding in terms of ions, is particularly appropriate for describing binary compounds formed from a metallic element, especially an s-block metal, and a nonmetallic element. An ionic solid is an assembly of cations and anions stacked together in a regular array. In sodium chloride, sodium ions alternate with chloride ions, and large numbers of oppositely charged ions are lined up in all three dimensions (Fig. 2.1). Ionic solids are examples of crystalline... 

The saline carbides are formed most commonly from the metals of Groups 1 and 2, aluminum, and a few other metals. The s-block metals form saline carbides when their oxides are heated with carbon. The anions present in saline carbides are either C>2 or C4. All the C4 carbides, which are called methides, produce methane and the corresponding hydroxide in water ... 

The s-block metals have low ionization energies, which enables them to easily lose electrons in chemical reactions. 

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... 

Other commonly employed redox electrodes are metals such as copper, cobalt, silver, zinc, nickel, and other transition metals. Some p-block metals such as tin, lead and indium can also function as redox electrodes. However, s-block metals such as magnesium do not make good redox electrodes since the elemental metal is reactive and forms a layer of oxide coating, which leads to poor reproducibility, poor electronic conductivity and electrode potentials that are difficult to interpret, (see Section 3.3.1). 

An equally impressive demonstration of this synergic reactivity of s-block metal amides is observed in the reaction of ferrocene with a mixture of BuNa, Bu2Mg and diisopropylamine. In this case, tetradeprotonation occurs regio-selectively to give the 1,1,3,3-tetraanion of ferrocene, which is trapped in the 16-membered heterometallic amide ring (6.22 in Figure 6.6). ... 

Where the lanthanide ionic radius and the macrocyclic cavity are incompatible, though in hydrous conditions the crown ether is likely to be displaced by water ligands, the crown may still be present in the structure of the crystal as a hydrogen-bonded adduct. This behaviour is seen in [Gd(N03)3(H20)3]-(18-crown-6).445 This type of compound is quite well known in the case of s block metals also, e.g. [Mg(H20)6]Cl2 (12-crown-4)454 and, a more subtle case, [Ca(nitrobenzoate)2(benzo-15-crown-5)]-3H20(benzo-15-crown-5)455 in which an apparent 2 1 complex has only half its crown ligand coordinated to Ca2+. 

The transition elements occupy A the central part of the periodic table, bridging the gap I between the active s-block metals of groups 1A and 2A on the left and the p-block metals, semimetals, and nonmetals of groups 3A-8A on the right (Figure 20.1). Because the d subshells are being filled in this region of the periodic table, the transition elements are also called the d-block elements. 

FIGURE 21.2 Primary mineral sources of metals. The s-block metals occur as chlorides, silicates, and carbonates. The d- and p-block metals are found as oxides and sulfides, except for the group 3B metals, which occur as phosphates, and the platinum-group metals and gold, which occur in uncombined form. There is no mineral source of technetium (Tc in group 7B), a radioactive element that is made in nuclear reactors. 

We might also expect to find oxide ores for the s-block metals and sulfide ores for the more electronegative p-block metals. In fact, sulfide ores are common for the p-block metals, except for A1 and Sn, but oxides of the s-block metals are strongly basic and far too reactive to exist in an environment that contains acidic oxides such as CO2 and SiC>2. Consequently, s-block metals are found in nature as carbonates, as silicates, and, in the case of Na and K, as chlorides (Sections 6.7 and 6.8). Only gold and the platinum-group metals (Ru, Os, Rh, Ir, Pd, and Pt) are sufficiently unreactive to occur commonly in uncombined form as the free metals. 

E R. E. Mulvey, s-Block metal inverse crowns synthetic and structural synergism in mixed alkali metal-magnesium (or zinc) amide chemistry. Chem. Commun. 1049-56 (2001). 

Cryptands and Cryptates Cages Made to Measure for s-Block Metals. 139... 

Fig. 12 Evolution of ligands containing sp3 oxygen donor atoms. Only crown-ethers (e.g. 8, 18-crown-6) and cryptands (e.g. 9, 2.2.2-crypt) form stable complexes with s-block metal ions...

Question 1.1 Using the information you have been given in Section 1.2, draw up a table comparing (in three columns) the characteristic features of the s-block metals (use group 1 as typical) and the d-block transition metals. 

Takeda, Y., Ikeo, N., and Sakata, N. Thermodynamic study of solvent extraction of 15-crown-5- and 16-crown-6-s-block metal ion complexes and tetraalkylammonium ions with picrate anions into chloroform. Talanta 1991, 38, 1325-1333. 

The enormous increase in readily available computing power since the 1980s has greatly affected the study of. s-block metal complexes. A long-standing assumption that the Group 1 and 2 metal ions (especially the former) could be successfully modeled as point charges in molecular orbital... 

The. s-block metals are commonly complexed with the macrocyclic cryptands, sepulchrates, and related species to form large, non-interacting cations that are used to stabilize a variety of... 

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