Transition metals periodic table

Elements measured Two-thirds of the periodic table transition metals, halogens, lanthanides, and platinum-group metals... 

Ab initio quantum chemistry has advanced so far in the last 40 years that it now allows the study of molecular systems containing any atom in the Periodic Table. Transition metal and actinide compounds can be treated routinely, provided that electron correlation1 and relativistic effects2 are properly taken into account. Computational quantum chemical methods can be employed in combination with experiment, to predict a priori, to confirm, or eventually, to refine experimental results. These methods can also predict the existence of new species, which may eventually be made by experimentalists. This latter use of computational quantum chemistry is especially important when one considers experiments that are not easy to handle in a laboratory, as, for example, explosive or radioactive species. It is clear that a good understanding of the chemistry of such species can be useful in several areas of scientific and technological exploration. Quantum chemistry can model molecular properties and transformations, and in... 

The transition metals are the elements found in Groups 3 through 12 and Periods 4 through 6 of the periodic table. Transition metals include a wide variety of metals that look and react differently depending on where they are placed within the groups. Most transition metals tend to be hard, shiny, and strong. The variety among these elements makes them important in countless products in the home, industry, and medicine. 

O transition metal a metal in the central block of the Periodic Table transition metals are hard, dense metals that form coloured compounds and can have more than one valency O reactivity series a listing of the metals in order of their reactivity 0 O electrochemical cell a cell made up of two metal electrodes of different reactivity placed it an... 

As we go from left to right across the transition metals in the periodic table, the metal atoms become smaller, much as in the lanthanide contraction (Section 2.6). Furthermore, the atoms of elements of the first transition series are smaller than those of corresponding members of the second and third. Consequently, interstitial carbides are particularly important for metals toward the lower left of the series, as with TiC, ZrC, TaC, and the extremely hard tungsten carbide WC, which is used industrially as an abrasive or cutting material of almost diamond like hardness. The parallel with trends in chemisorption (Section 6.1) will be apparent. 

Find, label by name and outline the following families on your periodic table alkali metals, alkaline earth metals, transition metals, halogens, and inert gases. Draw a dark line to show the separation between metals and nonmetals. Also, draw lines to enclose the metalloids. Colored pencils can be used to distinguish between the families. 

Part of the last two periods of transition metals are placed toward the bottom of the periodic table to keep the table conveniently narrow, as shown in Figure 13. The elements in the first of these rows are called the lanthanides because their atomic numbers follow the element lanthanum. Likewise, elements in the row below the lanthanides are called actinides because they follow actinium. As one moves left to right along these rows, electrons are added to the 4/orbitals in the lanthanides and to the 5/ orbitals in the actinides. For this reason, the lanthanides and actinides are sometimes called the /-block of the periodic table. 

Chromium, molybdenum, and tungsten are the transition metals in Group 6 of the periodic table. Chromium metal has the outer electronic configuration. W54,yl and forms compounds in oxidation states II- to VI+.1 The extensive organometallic chemistry of Cr is covered in the accompanying Comprehensive Organometallic Chemistry series, and this review is generally restricted to the coordination complexes (oxidation states 0 to VI+). 

In Chapter 3, you learned that the elements known as transition elements are located in Groups 3 through 12 in the periodic table. Transition elements form positive ions just as other metals do, but most transition elements can form more than one type of positive ion. In other words, transition elements can have more than one oxidation number. For example, copper can form both Cu and Cu ions, and iron can form both Fe + and Fe ions. Figure 5.6 shows the two compounds that iron forms with the sulfate ion. Zinc and silver are two exceptions to the variability of other transition elements each forms one type of ion. The zinc ion is Zn + and the silver ion is Ag+. 

Boron is a most interesting element, it being at the changeover point in the Periodic Table from metals to non-metals. It is non-metallic, and with the possibilities of hybridisation is able to form a wide range of hydrides, oxides, halides and compounds with transition elements. It is of great importance in the field of inorganic polymers. 

Table 22.3 shows the standard electrode potentials of the Period 4 transition metals in their -1-2 oxidation state in acid solution. Note that, in general, reducing strength decreases across the series. All the Period 4 transition metals, except copper, are active enough to reduce from aqueous acid to form hydrogen gas. In contrast to the rapid reaction at room temperature of the Group 1A(1) and 2A(2) metals with water, however, the transition metals have an oxide coating that allows rapid reaction only with hot water or steam. 

Catalysis by transition-metal surfaces exhibit trends across the periodic table whereby metals that form chemical bonds of intermediate strength have the highest activities. 

Let us now describe the electronic structure of the transition metals with the aid of the band model. According to this model the metal is a collective source of electrons and electron holes (Fig. 5-23). In a row of the periodic table, the metals on the left have fewer d electrons to fill the bands. There are two regions of energetic states, namely, the valence band and the conduction band with mobile electrons or positive holes. The potential energy of the electrons is characterized by the Fermi level, which corresponds to the electrochemical potential of the electrons and electron holes. 

Table 22.1 Orbital Occupancy of the Period 4 Transition Metals...

Period 4 transition metals, oxidation states Table 22.2, p. 741... 

A few of the heavy metals are among the most harmful of the elemental pollutants and are of particular concern because of their toxicities to humans. These elements are, in general, the transition metals and some of the representative elements, such as lead and tin, in the lower right-hand corner of the periodic table. Heavy metals include essential elements like iron and toxic metals like cadmium and mercury. Most of them have a tremendous affinity for sulfur and disrupt enzyme function by forming bonds with sulfur groups in enzymes. Protein carboxylic acid (-CO2H) and... 

The fourth network component, the inert-pair effect, states that the valence ns electrons of main-group metallic elements, particularly those to the right of the second- and third-row transition metals, are less reactive than expected. These relatively inert ns pairs mean that elements such as In, Tl, Sn, Pb, Sb, Bi, and Po often form compounds where the oxidation state is 2 less than the expected group valence. The two major reasons for this effect are (1) larger-than-normal effective nuclear charges in these elements and (2) lower bond energies in their compounds. The fifth network component, the metal-nonmetal line, is just the division of the periodic table into metal, nonmetal, and metalloid regions. 

The more at the right of the periodic table the metal is located, the more d electrons it has, and it will be easier to complete its coordination sphere with 18 valence electrons. On the other hand, the early transition metals may have an average or weak tendency to fulfill the 18-electron shell. It can even happen that. 

---