Electronegative divalent element

In the solid state the two frequencies vary with the nature of the metallic ion. For mono- and divalent elements there is a linear relationship between the electronegativity of the element and the... 

Compounds having divalent sulfur and selenium atoms bound to more electronegative elements react with alkenes to give addition products. The mechanism is similar to that in halogenation and involves of bridged cationic intermediates. 

Rare earth elements are the general term for 15 kinds of lanthanide elements (La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Py, Ho, Er, Tm, Yb, Lu) together with Sc and Y elements. They prefer trivalent states in the complex formation, though three elements (Eu, Sm, Yb) can assume tri- and divalent stateos and Ce a tri- or tetravalent state. Their ionic radii are fairly large (1.0-1.17 A) and their electronegativities are low (1.1-1.2). In fact, the former are much larger than those of... 

Biltz-Zen trend have been discussed and represented as a function of a charge transfer atomic parameter which correlates with Pauling s electronegativity. This approach has been successfully employed for groups of binary alloys formed by the alkaline earths and the divalent rare earth elements. 

Germanium is disposed in the center of group 14 of the periodic table of the elements. Increased stability of divalent species, which is more pronounced for tin and lead, begins from this element. The main characteristics of these atoms, such as atomic radius, energy of ionization, electron affinity, electronegativity and other features, are presented in parallel in a review12. 

Estimates of formation enthalpies of MX2 and MX4 (X = F, Cl, Br, I, S042", C032, N03 and P043 ) for Po and element 116 [150] made on the basis of the MCDF atomic calculations confirmed the instability of the 4+ state of element 116. The chemistry of element 116 is expected to be mainly cationic an ease of formation of the divalent compounds should approach that of Be or Mn, and tetravalent compounds should be formed with the most electronegative atoms, e.g., 116F4. 

The successful generation, by precipitation out of liquid anhydrous HF, of fluorides thermodynamically unstable with respect to loss of elemental F2, gave a forceful reminder of the remarkable stability of that solvent towards oxidation. Soon after the preparation of AgFa, in attempts to find evidence for cationic derivatives (e.g. [AgF2] ), it was discovered (see Ref. 98) that even divalent silver, as a cation, Ag + (solvated by HF), had the capability to oxidize Xe. This made chemical sense, since a cation, having an electron deficit, should have higher electronegativity than a related oxidation-state in a neutral or anionic species. Indeed, this had three important consequences. 

Only Eu and Yb, among the rare earths, form immiscibility gaps with Sc in the liquid and solid. The difference in valence of these two rare earths and Sc is, perhaps, the main reason of this difference of interaction. The divalent state is more typical for Eu and Yb, whereas the other rare earths are usually trivalent. The same divalent state is characteristic for aUcaline earths which are immiscible with Sc in the liquid and solid too. Therefore, it is possible to predict the same type of binary phase diagrams of Sc with alkaline metals. These elements are even more different from Sc in the valence state and other characteristics (melting temperature, electronegativity, etc.) than are the alkaline-earth metals. 

Class 1 denotes the samples forming intermediate compound, class 2 denotes the samples without intermediate compound formation, R+ and R2+ denote the ionic radii of monovalent and divalent cations respectively and X+ and X2+ denote the electronegativities of monovalent and divalent metallic elements respectively. 

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