Transition elements, physical properties

PHYSICAL PROPERTIES OF THE FIRST TRANSITION SERIES ELEMENTS... 

Nickel occurs in the first transition row in Group 10 (VIIIB) of the Periodic Table. Some physical properties are given in Table 1 (1 4). Nickel is a high melting point element having a ductile crystal stmcture. Its chemical properties allow it to be combined with other elements to form many alloys. 

The Niccolite Structure. The substances which crystallize with the niccolite structure (B8) are compounds of transition elements with S, Se, Te, As, Sb, Bi, or Sn. The physical properties of the substances indicate that the crystals are not ionic, and this is substantiated by the lack of agreement with the structural rules for ionic crystals. Thus each metal atom is surrounded by an octahedron of non-metal atoms but these octahedra share faces, and the edges of the shared faces are longer than other edges (rather than shorter, as in ionic crystals). Hence we conclude that the bonds are covalent, with probably some metallic character also. 

Apart from d- and 4f-based magnetic systems, the physical properties of actinides can be classified to be intermediate between the lanthanides and d-electron metals. 5f-electron states form bands whose width lies in between those of d- and 4f-electron states. On the other hand, the spin-orbit interaction increases as a function of atomic number and is the largest for actinides. Therefore, one can see direct similarity between the light actinides, up to plutonium, and the transition metals on one side, and the heavy actinides and 4f elements on the other side. In general, the presence or absence of magnetic order in actinides depends on the shortest distance between 5f atoms (Hill limit). 

Chromium is a silvery white/gray, hard, brittle noncorrosive metal that has chemical and physical properties similar to the two preceding elements in period 4 (V andTi). As one of the transition elements, its uses its M shell rather than its outer N shell for valence electrons when combining with other elements. Its melting point is 1,857°C, its boiling point is 2,672°C, and its density is 7.19 g/cm. ... 

Although cadmium is not considered a transition element in some periodic tables, it is the central element of the triad with zinc and mercury. Zinc is just above it and mercury is below it in group 12 of the periodic table. Cadmiums chemical and physical properties are similar to its group 12 mates. Their electronegativity is very similar Zn = 1.6, Cd = 1.7, and Hg = 1.9. 

Rhenium is one of the transition elements, which range from metals to metal-like elements. Its chemical and physical properties are similar to those of technetium, which is above it in the periodic table. It is not very reactive. When small amounts are added to molybdenum, it forms a unique type of semiconducting metal. It is also noncorrosive in seawater. 

The lanthanide series is composed of metallic elements with similar physical properties, chemical characteristics, and unique structures. These elements are found in period 6, starting at group 3 of the periodic table. The lanthanide series may also be thought of as an extension of the transition elements, but the lanthanide elements are presented in a separate row of period 6 at the bottom of the periodic table. 

The substitution for Cu by a 3d metal produces drastic changes in the physical properties of the 90K phase, as shown in Figure 9a where the Tc s (as determined by ac-susceptibility measurements)are plotted as a function of x for the various series. Independent of the magnetic nature of the substituted element, for the trivalent ions (Fe, Co, and Al) Tc remains constant and equal to 90K up to the O-T transition and then decreases continuously to less than 4.2K at x-0.5. Upon increasing x further, the compounds become semiconductors and simultaneously antiferromagnetism associated with the Cu ions develops. In contrast to this behavior, for the divalent substituted Ni and Zn ions Tc decreases markedly, even at low x. 

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