Transition elements general properties

FIGURE 4.13 Main-group and transition elements The periodic table can be broadly divided into main-group elements, whose properties can generally be predicted based on their position, and transition elements, whose properties tend to be less predictable based on their position. 

Attempts to classify carbides according to structure or bond type meet the same difficulties as were encountered with hydrides (p. 64) and borides (p. 145) and for the same reasons. The general trends in properties of the three groups of compounds are, however, broadly similar, being most polar (ionic) for the electropositive metals, most covalent (molecular) for the electronegative non-metals and somewhat complex (interstitial) for the elements in the centre of the d block. There are also several elements with poorly characterized, unstable, or non-existent carbides, namely the later transition elements (Groups 11 and 12), the platinum metals, and the post transition-metal elements in Group 13. 

As pure elements, almost all the transition metals are solids that conduct heat and electricity and are malleable and ductile. Although they share these general properties, transition metals display variations in other properties that can be traced to their different numbers of valence electrons. 

There are several general ways to categorize elements in groups 13 to 16. These are metals different in several ways from the transition elements. They range from metallics (other metals) to metalloids (semiconductors) to nonmetals. The elements in these groups are arranged according to their properties, characteristics, and the position of their electrons in their atoms outer shells. These, and other factors, determine how they are depicted in the periodic table. 

It may be supposed that the appropriate model is the same for all the transition metals of the same row of the periodic table because of the similarities of these elements. It may only be necessary to eliminate the terms containing 0 or 1 d electrons for which the general properties are different. ... 

With our broad definition in mind, we find that there are now some 56 transition elements, counting the heaviest elements through the one of atomic number 104. Clearly the majority of all known elements are transition elements. All these transition elements have certain general properties in common ... 

Due to their oxophilic nature, early transition metals show general properties which somehow recall those of the main group elements and lanthanides and afford O-bonded... 

The lanthanides, for which the general symbol Ln is used here, have electron configurations with fis in common and a variable occupation of the 4f level. Classically called the Rare Earths, they are also referred to as the inner-transition elements because the 4f electron build-up takes place in the fourth quantum level, below the 5s, 5p and 6s electrons. As the electronic diversity between the atoms is at some depth the elements are very similar chemically. The small differences in properties arise principally from the... 

The chemical properties of the other essential transition elements simplify their transport properties. For zinc there is only the -f 2 oxidation state, and the hydrolysis of this ion is not a limiting feature of its solubility or transport. Zinc is an essential element for both animals and plants.In general, metal ion uptake into the roots of plants is an extremely complex phenomenon. A cross-sectional diagram of a root is shown in Figure 1.6. It is said that both diffusion... 

Knowledge Required (1) The meaning of the term transition elements. (2) The general properties of transition elements, based on their position on the periodic table. 

For a surface-catalyzed reaction to occur, chemical bonds must be involved, and so our interest is primarily with chemisorption. Again, some general classifications of various metals for chemisorption of gases are possible, as shown in Table 2.1-3 from Coughlin [26], and similar properties are involved. Note that the transition elements of the periodic table are frequently involved, and this appears to be based on the electronic nature of their d-orbitals. 

Skill 21.3 Demonstrate knowledge of the general features and properties of compounds of metals, nonmetals, and transition elements and the materials derived from them. 

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