Group 12 Mercury Zinc

Unlike cadmium and mercury and, in fact, all metals of Group II, zinc dissolves readily in alkalis forming zincates. in which the zinc atom is contained in a complex hydroxo-anion, for example ... 

Zinc and cadmium are both silvery, reactive metals that are similar to each other but differ sharply from mercury. Zinc is amphoteric (like its main-group neighbor aluminum). It reacts with acids to form Zn2+ ions and with alkalis to form the zincate ion, [Zn(OH)4]2 ... 

The chalcogenides are binary compounds of a chalcogen (i.e., the elements of Group Ilb zinc, cadmium, mercury) with a less electropositive element, such as those of Group VIb (oxygen, sulfur, selenium, and tellurium). This section covers the sulfides, selenides, andtellurides. Oxides are reviewed above in Ch. 11. Most of the chalcogenides have useful optical characteristics and their applications are usually found in optics. 

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. 

The (/-block elements tend to lose their valence s-electrons when they form compounds. Most of them can also lose a variable number of d-electrons and show variable valence. The only elements of the block that do not use their (/-electrons in compound formation are the members of Group 12 (zinc, cadmium, and mercury). The ability to exist in different oxidation states is responsible for many of the special properties of these elements and plays a role in the action of many vital biomolecules (Box 16.1). 

Group 12 zinc, cadmium and mercury (G4) Complexes structure and isomerism (H6)... 

Dialkyl derivatives of elements of the Second sub-Group, namely, zinc, cadmium, and mercury, contain an almost completely covalent metal-carbon bond. These compounds are normal, unassociated liquids with low boiling points e.g., the dimethyl derivative of zinc boils at 46°, that of cadmium at 105.5°, and that of mercury at 92°. 

Alkyl Bound to a Metal. The alkyl group may be caused to unite with metals, such as lead, mercury, zinc, magnesium, and arsenic. Examples of this type of alkylation are tetraethyllead, merthiolate, ethyl mercury chloride, and ethyl mercury phosphate. Among the lethal poison gases... 

Clemmensen reduction The reduction of a carbonyl group to a methylene group by zinc amalgam, Zn(Hg), in dilute hydrochloric acid. (p. 778) amalgam An alloy of a metal with mercury. 

It had become clearer that the Hght from a glowing soHd body shows a conHnuous spectrum while a metal that is vaporized emits a characterisHc line spectrum. The yeUow doublet in the sodium spectrum was an example. Charles Wheatstone, well known from the science of electricity, in 1835 invesHgated electrical arcs generated between metal electrodes. The metals he used were mercury, zinc, cadmium, Hn, bismuth and lead. He used a prism for studying the radiaHon from the arcs and observed the disHnct Hnes that consHtuted the spectrum. Further he noted that each metal had its special group of Hnes, which could possibly be used for element idenH-ficaHon. 

The symmetric methyl deformation vibration absorbs strongly at 1240-1230 cm" in Ge—CH3 compounds and 1200-1180 cm" in Sn—CH3 compounds/ Methyl rocking vibrations absorb strongly at 900-700 cm The CH2-metal group absorbs at 1430-1415 cm" (CH2 deformation) in compounds with such metals as mercury, zinc, cadmium, or tin. ... 

Group 11 Copper, Silver, and Gold 23-7 Group 12 Zinc, Cadmium, and Mercury... 

These elements formed Group IIB of Mendeleef s original periodic table. As we have seen in Chapter 13, zinc does not show very marked transition-metaf characteristics. The other two elements in this group, cadmium and mercury, lie at the ends of the second and third transition series (Y-Cd, La-Hg) and, although they resemble zinc in some respects in showing a predominantly - - 2 oxidation state, they also show rather more transition-metal characteristics. Additionally, mercury has characteristics, some of which relate it quite closely to its immediate predecessors in the third transition series, platinum and gold, and some of which are decidedly peculiar to mercury. 

The methylthio group is removed by treatment with zinc powder in HCl (276) to give the 2-unsubstituted thiazole. The action of aluminum-mercury amalgam in methanol on various thioethers is reported to yield the expected thiazole (108) when Rj is an alkyl group and the corresponding A-4-thiazoline-2-thione (109) when Rj PhCH - (Scheme 55) (169). 

Group 12 (IIB) Perchlorates. The zinc perchlorate [13637-61 -17, cadmium perchlorate [13760-37-7] mercury(I) perchlorate [13932-02-0] and mercury(II) perchlorate [7616-83-3] all exist. Cell potential measurements show that zinc and cadmium perchlorates are completely dissociated in concentrations up to 0.1 molar in aqueous solutions (47—49). Mercurous perchlorate forms a tetrahydrate that can be readily converted to the dihydrate on heating to above 36°C (50). 

MIR), requires the introduction of new x-ray scatterers into the unit cell of the crystal. These additions should be heavy atoms (so that they make a significant contribution to the diffraction pattern) there should not be too many of them (so that their positions can be located) and they should not change the structure of the molecule or of the crystal cell—in other words, the crystals should be isomorphous. In practice, isomorphous replacement is usually done by diffusing different heavy-metal complexes into the channels of preformed protein crystals. With luck the protein molecules expose side chains in these solvent channels, such as SH groups, that are able to bind heavy metals. It is also possible to replace endogenous light metals in metal-loproteins with heavier ones, e.g., zinc by mercury or calcium by samarium. 

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