P-Block metals

Elements on the left of the p block, especially the heavier elements, have ionization energies that are low enough for these elements to have some of the metallic properties of the members of the s block. However, the ionization energies of the p-block metals are quite high, and they are less reactive than those in the s block. The elements aluminum, tin, and lead, which are important construction materials, all lie in this region of the periodic table (Fig. 1.61). 

All d-block elements are metals with properties between those ofs-block and p-block metals. Many d-block elements form cations in more than one oxidation state. 

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

Aluminum is unique among the main group metals. All other p block metals have filled valence d orbitals. As a consequence, these metals have much in common with their transition metal neighbors. They tend to be soft Lewis bases. Aluminum, on the other hand, lacks a filled d orbital set and is a hard Lewis acid that has more in common with its nearest neighbor, magnesium. Highly reactive, aluminum is found naturally in the +3 oxidation state and is difficult to reduce to the pure metal. Thus, although tin and lead have been known since antiquity, aluminum was not discovered until 1825 and did not become a common commodity until more than 60 years later. 

III. Terminal Alkyl Derivatives of the s- and p-Block Metals Supported by Poly(pyrazolyl)borato Ligation... 

In contrast to these adducts in which the boratabenzene ring is bound ti to the main-group metal, reaction of [C5H5B-Me]Li with PbCl2 affords a bent-sandwich complex, Pbfi/ -CsI LBMeh.31 This report provided the first structural characterization of an r 6-bonding mode to a p-block metal. Reaction of Pb(Ti6-C5H5BMe)2 with a Lewis base such as bipyridine leads to a complex wherein the bipyridine is bound in the pseudoequatorial plane. 

Periodic variations in the surface tension of liquid metals, c1 , are shown in Figure 6.5. The much higher surface tension of rf-block metals compared to the s- and p-block metals suggests that the surface tension relates to the strength of interatomic bonding. Similar periodic trends can be found also for the melting temperature and the enthalpy of vaporization, and the surface tension of liquid metals is strongly... 

Hydrides of variable composition are not only formed with pure metals as solvents. A large number of the binary metal hydrides are non-stoichiometric compounds. Non-stoichiometric compounds are in general common for d,f and some p block metals in combination with soft anions such as sulfur, selenium and hydrogen, and also for somewhat harder anions like oxygen. Hard anions such as the halides, sulfates and nitrides form few non-stoichiometric compounds. Two factors are important the crystal structures must allow changes in composition, and the transition metal must have accessible oxidation states. These factors are partly related. FeO,... 

Y. Inoue, New photocatalyst group for water decomposition of Ru02-loaded p-block metal (In, Sn, and Sb) oxides with d10 configuration, J. Phys. Chem. B 105 (2001) 6061-6063. 

Y. Inoue, Photocatalytic activity of the Ru02-dispersed composite p-block metal oxide LiInGe04 with d10-d10 configuration for water decomposition,... 

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). 

The present discussion has been restricted to oxides of the lighter metals of the periodic table. At present, owing to lack of data, it is difficult to judge whether the classification can be applied to the second and third row transition metals and also it is not clear to which classification p block metal oxides belong. Possibly a third classification metallic to covalent should be included, and this would enable relating oxides to each other in terms of a Ketelaar triangle 33. ... 

Now we can work out the formula of an ionic compound formed between the monatomic ions of two main-group elements, one a metal and the other a nonmetal. Unless a lower oxidation number is specified (as for the p-block metals), the metal atom loses all its valence electrons, and the nonmetal atom gains enough electrons to complete its valence shell. Then we adjust the numbers of cations and anions so that the resulting compound is electrically neutral. A simple example is calcium chloride. The calcium atoms ([Ar]4s2) each lose two electrons, to form... 

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. 

Heavier p-block metals often occur with an oxidation state 2 less then the group value... 

P-block metals in acidic solution. p-block metals in acidic solution. 

---