Sodium electronic structure

W. Schroder, and J. Holzl, Electronic structure of adsorbed sodium on Pt(III), Solid State Communications 24, 777-780 (1977). 

It is also shown that theoretically a binary compound should have the sphalerite or wurzite structure instead of the sodium chloride structure if the radius ratio is less than 0.33. The oxide, sulfide, selenide and telluride of beryllium conform to this requirement, and are to be considered as ionic crystals. It is found, however, that such tetrahedral crystals are particularly apt to show deformation, and it is suggested that this is a tendency of the anion to share an electron pair with each cation. 

The brittleness of these intermetallic compounds suggests an electronic structure involving a filled Brillouin zone. It was pointed out by Ketelaar (1937) that the strongest reflection, that of form 531, corresponds to a Brillouin polyhedron for which the inscribed sphere has a volume of 217 electrons per unit cube, which agrees well with the value 216 calculated on the assumption that the sodium atom is univalent and the zinc atoms are bivalent that is, calculated in the usual Hume-Rothery way. It has also been... 

Based on the ionic radii, nine of the alkali halides should not have the sodium chloride structure. However, only three, CsCl, CsBr, and Csl, do not have the sodium chloride structure. This means that the hard sphere approach to ionic arrangement is inadequate. It should be mentioned that it does predict the correct arrangement of ions in the majority of cases. It is a guide, not an infallible rule. One of the factors that is not included is related to the fact that the electron clouds of ions have some ability to be deformed. This electronic polarizability leads to additional forces of the types that were discussed in the previous chapter. Distorting the electron cloud of an anion leads to part of its electron density being drawn toward the cations surrounding it. In essence, there is some sharing of electron density as a result. Thus the bond has become partially covalent. 

Nickel oxide, NiO, is doped with lithium oxide, Li20, to form Li Ni, xO with the sodium chloride structure, (a) Derive the form of the Heikes equation for the variation of Seebeck coefficient, a, with the degree of doping, x. The following table gives values of a versus log[(l-x)/x] for this material, (b) Are the current carriers holes or electrons (c) Estimate the value of the constant term k/e. 

At low temperatures magnesium oxide, MgO, which adopts the sodium chloride structure, is virtually a stoichiometric phase, but at high temperatures in the MgO-A1203 system this is not so. At 1800°C the approximate composition range is from pure MgO to 5 mol % A1203 95 mol % MgO. The simplest way to account for this composition range is to assume that point defects are responsible. For this, because both Mg2+ and Al3+ cations in this system have a fixed valence, electronic compensation is unreasonable. There are then three ways to account for the composition range structurally ... 

If an electron is removed from an inner energy level of one of the heavier elements (in practice, with an atomic number greater than sodium), a vacancy or hole is produced in the electronic structure. This is an unstable arrangement, and two competing processes act to rectify this ... 

At first glance, the standard potentials listed in Table 1 are largely nondescript. All are quite similar, with the possible exception of the sodium couple, which might appear to be anomalously positive. These values are qualitatively consistent with the simple picture that develops upon consideration of the electronic structures of the metals and their oxidized monovalent cations. Each of the metals exhibits an electronic structure that can be symbolized by (noble gas) s, where the principal quantum number (n) ranges from 2 < < 7. For example, the electronic structure for potassium is [Ar]4s, that is, ls 2s 2p 3s 3p 4sk Each of the alkali metals can easily lose one electron to give a stable monovalent metal cation that is isoelectronic with the noble gas... 

In the sodium chloride structure, the symmetry enables three of the five d orbitals on different atoms to overlap. Because the atoms are not nearest neighbours, the overlap is not as large as in pure metals and the bands are thus narrow. The other two d orbitals overlap with orbitals on the adjacent oxygens. Thus, two narrow 3c/ bands exist. The lower one, labelled 2g. can take up to 67Velectrons, and the upper one, labelled 6g, up to 47V electrons. Divalent titanium has two d electrons, therefore, 27V electrons fill the 37V levels of the lower band. Similarly, divalent vanadium has three d electrons and so the lower band is half full. As in the case of pure metals, a partly filled band leads to metallic conductivity. For FeO, the /2g band would be full, so it is not surprising to find that it is a semiconductor but MnO with only five electrons per manganese is also a semiconductor. 

These salts were found to be soluble in polar organic solvents as well as in water. Their electrochemistry also shows a continuum of current due to the successive filling of electronic states of the nanotube. Figure 8.11 shows the cyclic voltammogram obtained for nanotubes reduced using sodium metal. Close observation reveals two broad waves around —0.81 and 1.01 V, which have been attributed to the more complex electronic structure of the pristine materials, as compared to derivatized nanotubes. This observation is in agreement with recent calculations indicating... 

The whole series of pyrrol-l-ylborates, M[BH (NC4H4)4 ], has been synthesized (Tables 9 and 12). The mechanism of their formation and their hydrolysis kinetics have been studied in detail.100 The hydropyrazol-l-ylborates are very stable compounds and can be prepared in acid form.101 The di- and tri-pyrazol-l-ylborates are extensively used as complexing ligands (see Chapter 13.6). The photoelectron spectra of the sodium and thalliumfl) hydrotris(pyrazol-l-yl)borates and the electronic structure of the anion itself are reported.11 ... 

J. W. Briihl s observations on the refractive indices agreed with the formula H0.0.N=0 but R. Lowenherz s values for ethyl, propyl, isobutyl, and amyl nitrates agree better with the quinquevalent nitrogen atom. H. E. Armstrong and F. P. Worley made some observations on the constitution of nitric acid—vide sulphuric acid. H. Burgarth, H. Remy, and H. Henstock discussed the electronic structure and from observations on the absorption spectra of sodium and potassium nitrates in different solvents, G. Scheibe inferred that the nitrate ion is dipolar, and that the electronic structure is such that the first of the following forms exists in equilibrium with small proportion of the second ... 

What is the same about the electron structures of a lithium, sodium and potassium ... 

Maunsbach, A.B., Skriver, E., Hebert, H. (1991). Two-dimensional crystals and three-dimensional structure of Na,K-ATPase analyzed by electron microscopy. In The Sodium Pump Structure, Mechanism, and Regulation (Kaplan, J.H. De Weer, P., eds.), pp. 159-172, The Rockefeller University Press, New York. 

A few moments thought about the nature of the surface of an oxide leads to the conclusion that the surface oxide ion should have quite different properties than the bulk lattice ions. For example, consider a simple cubic oxide such as MO with a sodium chloride structure where each ion is sixfold coordinated if this is cleaved along a <100) plane, then the coordination of the ions in this plane is reduced from six- to fivefold. This new surface will not be ideal, and ions of still lower coordination will also be present where higher index planes are exposed at the surface. However, for MgO prepared by thermal decomposition of the hydroxide or carbonate, evidence from electron microscopy (130) indicates that these have high index planes that... 

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