Metallic bonding in mercury

The mercury atom is smaller than expected from the zinc-cadmium trend and is more difficult to ionize than the lighter atoms. In consequence the metal-metal bonding in mercury is relatively poor, resulting in the element being a liquid in its standard state. This almost Group 18 behaviour of mercury may be compared to that of a real Group 18 element, xenon, which has first and second ionization energies of 1170 and 2050 kJ mol. ... 

Commentary on Experimental Study of the Transition from van der Waals, over Covalent to Metallic Bonding in Mercury Clusters, H. Haberland, H. Kommeier, H. Langosch, M. Oschwald and G. Tanner, J. Chem. Soc., Faraday Trans., 1990, 86, 2473. 

Experimental Study of the Transition from van der Waals, over Covalent to Metallic Bonding in Mercury Clusters... 

Haberland, H., Kornmeier, H., Langosch, H., Oschwald, M., and Tanner, G., Experimental study of the transition from van der Waals over covalent to metallic bonding in mercury clusters, /. Chem. Soc. Farad. Trans., 86, 2473,1990. 

For all three metals the strong bonds have bond numbers equal to i to within the reliability of their evaluation (0.48 is found for the six strong bonds in mercury, too). Bond numbers approximately equal to the ratios of small integers occur rather often, and special stability may be associated with them. 

Breaking of silicon-transition-metal bonds by mercury compounds is one aspect of the well-known "conversion series in organosilicon chemistry (22, 24, 154). It was established at an early stage that equilibrium in the system... 

Mercury itself is capable of interacting by two main interatomic forces, the metallic bond and London dispersion forces. Similarly, water has the potential for both hydrogen bond and London dispersion force interactions. However, hydrocarbons cannot interact with either the metallic bond, in the case of mercury, or hydrogen bonds, in the case of water. Therefore, the only primary interatomic force within hydrocarbons and across the interface is due to the London dispersion interaction, and... 

Mercury forms two series of compounds, mercurous and mercuric, but the former are not compounds of monovalent Hg in the sense that cuprous compounds, for example, are derivatives of monovalent Cu. A number of elements form compounds in which there are metal-metal bonds but mercury is unique in forming, in addition to Hg and the normal mercuric compounds, a series of compounds based on the grouping (-Hg-Hg-). (Evidence for the formation of the Cdf ion in molten Cd2(AlCl4)2 at 250°C is limited to the observation of one Raman line. )... 

The metal with the weakest metallic bonds is mercury. Hg is a liquid at room temperature because Hg atoms hold on tightly to a stable valence configuration of full s, f, and d subshells. Fewer electrons are shared to create bonds than in other metals. 

Intermolecular forces in saturated hydrocarbons are practically entirely due to the London dispersion forces. These forces are the result of the interaction of fluctuating electric dipoles with the induced dipoles they contribute to the cohesion in all substances, but their magnitude depends on the type of material and its density. Many substances have other intermolecular forces in addition to the dispersion forces. In the case of mercury, the interatomic forces involve the dispersion forces and the metallic bond in the case of water, they involve dispersion forces and dipole interactions (mainly hydrogen bonds). Since the dispersion forces are not appreciably influenced by other intermolecular forces, one can assume dispersion forces and other intermolecular forces generally to be additive. Thus, in the case of the surface tension of water, the surface tension can be considered the sum of a contribution resulting from dispersion forces, y and a contribution resulting from the dipole interactions, mainly hydrogen bonds,... 

Dirac himself dismissed the idea that relativity could impinge on chemistry, he was in fact mistaken, and certainly all the third Transition Series and later elements are subject to its influence. The resulting orbital contraction is additional to the non-relativistic Lanthanide Contraction, and is partly responsible for the close correspondence in sizes between the second and third Series, already noted. It also accounts for the difference in colour and in chemistry between silver and gold, for the unusual structure and weak bonding in mercury, and for many other facets of the chemistry of the heavier elements traditionally associated with the stability of the 6 electron pair.bi2-i8,20-22 electronegative metal, and... 

Table 14.2 shows that all three elements have remarkably low melting points and boiling points—an indication of the weak metallic bonding, especially notable in mercury. The low heat of atomisation of the latter element compensates to some extent its higher ionisation energies, so that, in practice, all the elements of this group can form cations in aqueous solution or in hydrated salts anhydrous mercuryfll) compounds are generally covalent. 

Formation of the Group-IB or -IIB-Group-IB or -IIB Metal Bonds 8.2.4. in Mercury(l) Compounds from Mercury(ll) Compounds... 

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