Sodium bonding energy

Pauling scale phys chem A numerical scale of electronegativities based on bond-energy calculations for different elements joined by covalent bonds. pol-iri Skal Pavy s solution analychem Laboratory reagent used to determine the concentration of sugars in solution by color titration contains copper sulfate, sodium potassium tartrate, sodium hydroxide, and ammonia in water solution. pa-vez S3,lu-sh3n Pb See lead. 

As shown in previous publications relative to absorption spectroscopy and ground-state equilibrium geometries, the sodium atom in a 3s state prefers to bind on the surface of a rare-gas cluster. This stems from the fact that the NaAr diatomics have a smaller bonding energy at a longer intemuclear distance than ArAr, in concordance with the rather large size of the isotropic 3 s orbital. 

In Chapter 3 the covalent bond has been discussed and the question now arises whether this is the only possible type of bond between atoms. Let us consider the gaseous molecule of sodium chloride. The sodium and chlorine atoms each have one unpaired electron, 35 in sodium and 3/> in chlorine, so that in principle the formation of a covalent bond is possible. The calculation of bond energies presents considerable difficulties even in a simple molecule such as hydrogen and the calculation for more complicated molecules is impossible except by an approximate method such as that introduced by Pauling In this method, it is assumed that the energy of the covalent bond A—B, is equal to one half of the sum of the bond energies of the homopolar molecules A—A and B—B, i.e. 

If this method of calculation is now applied to molecules such as NaCl, LiF and KBr, we find considerable discrepancies between the calculated and experimental values. Thus for sodium chloride the bond energy of the covalent bond will be ... 

We thus have evidence that the differences between bond energies vary in simple hydro-carbons and in substituted hydrocarbons but so far this leaves us in the dark as to the variations of the individual values. Definite indications—if only of an approximate nature—of wide variations in bond energies were first postulated by Ogg and Polanyi from the variations in the rates of reaction between organic halides and sodium vapour observed by Hartel and Polanyi.More recently H. S. Taylor and Smith derived similar conclusions from the marked variations in the rate of reaction of methyl radicals with hydrocarbons. A fall in the bond energy of C—H was quite recently confirmed and quantitatively fixed by more direct methods. D. P. Stevenson has given the values as D CHs—H) = loi and D CjH5—H) = 96 while independently and by different methods Anderson, Kistiakowsky and van Arstdalen obtain D(CH3—H) = 102 and D(C H5—H) = 98 kcal. 

The metabolic and/or hydrolytic products of parathion encountered as residues in the urine include both diethyl phosphoric acid and diethyl phosphorothioic acid, most probably as their salts (potassium or sodium). Derivatization of these residues with diazomethane would result in the formation of three trialkyl phosphate compounds, namely, 0,0-diethyl O-methyl phosphate (DEMMP), 0,0-diethyl 0-methyl phosphoro-thionate (DEMMTP), and 0,0-diethyl S-methyl phosphorothiolate (DEMMPTh). Earlier (15), it had been shown by combined gas chromatography-mass spectrometry and other analytical data that a later-eluting major product ca. 85%) of the methylation of diethyl phosphorothioic acid formed under the conditions of the analytical method was DEMMPTh, and the minor product formed (ca. 15%) was DEMMTP. Accordingly, all three trialkyl phosphates were observed and confirmed by mass spectrometry in the analysis of the human urine extract. Sufficient internal bond energy differences are associated with the isomeric structures DEMMPTh and DEMMTP that qualitatively and quantitatively dissimilar fragmentation patterns are observed for both isomers as can be seen from the mass spectra of these compounds shown in Figure 4. 

Fig. 4.9 Energies of free cations and of ionic compounds as a function of the oxidation state of the cation. Top Lines represent the ionization energy necessary to form the +1. +2, +3, and + 4 cations of sodium, magnesium, and aluminum. Note that although the ionization energy increases most sharply when a noble gas configuration is broken, isolated cations are always less stable in Itiifher oxidation states. Bottom Lines represent the sum of ionization energy and ionic bonding energy for hypothetical molecules MX, MXj, MXj, and MX in which the interatomic distance, r, has been arbitrarily set at 200 pm. Note that the most stable compounds (identified by arrows) arc NaX, MgXj, and AlXj. (All of the.se molecules will be stabilized additionally to a small extent by the electron affinity of X.)...

Beezer, A. E., Mortimer, C. T., and Tyler, E. G., 1965, Heats of formation and bond energies. Part XIII. Arsenic tribromide, arsenious and arsenic oxides, and aqueous solutions of sodium arsenite and sodium arsenate Journal of the Chemical Society (A), p. 4471-4478. 

---