Multi-atom Ions

All the compounds we ve looked at so far have been binary compounds, i.e. they contain only two elements. Note that the names of binary compounds end in -ide. What if they contain more than two Fortunately most non-binary compounds contain what are called multi-atom ions. These are groups of atoms that behave as if they were a single ion. Some examples are  

To write the formulae of these compounds, all you have got to do is recognise the fact that they contain a multi-atom ion, look up its formula and oxidation number and follow the rules. 

What if there is more than one multi-atom ion present Let us look at calcium nitrate. 

Just to complicate things a little further, there are actually two sulfate ions. That s because sulfur has different oxidation numbers. The sulfate ion given above is the sulfate(Vl) ion, because the sulfur atom in it has an oxidation number of +6. The whole multi-atom ion has oxidation number —2, because there is one sulfur and four oxygens. Each oxygen has the oxidation number —2, the sulfur is -I- 6, and so H-6 -I- [4 X (-2)] = -2. 

There is another sulfate ion called the sulfate(IV) ion, because the sulfur in it has the oxidation number -1-4. Its formula is SO , and it is usually still known as the sulfite ion. Each oxygen has an oxidation number of —2, so the oxidation number of the ion as a whole is -1-4 -I- [3 X (—2)] = —2. So sodium sulfate(IV) is Na2S03. 

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Similarly, there are nitrate(V) and nitrate(III) multi-atom ions. The former is the one we ve come across, NOj, with an oxidation number of — 1, because -1-5 (for the nitrogen) -i- [3 X (—2)] = —1. This is usually simply called nitrate. 

One part of the formula may be a multi-atom ion which remains intact after the reaction [e.g. the reaction shown below of sodium chloride with silver nitrate to give sodium nitrate and silver chloride, the nitrate ion (NO ) remains unchanged]. It is not necessary to count the individual atoms of the multiple atom ion separately, you can just count groups . 

Buryakov, I.A. Krylov, E.V. Nazarov, E.G. Rasulev, U.K., A new method of separation of multi-atomic ions by mobility at atmospheric pressure using a high-frequency amplitude-asymmetric strong electric field, Int. J. Mass Spec. Ion Proc. 1993,128,143-148. 

The radii of multi-atomic ions was estimated as thermochemical radii by Jenkins and co-workers (Jenkins and Thakur 1979 Jenkins et al. 1999 Roobottom et al. 1999) from the lattice potential energies f/iat of crystals containing them with a monatomic counter-ion of known radius. The sum of the radii of the cation and anion is ... 

The temperature dependence of the ionic radii of monatomic- as well as multi-atomic ions is negligible within the temperature range of the existence of water as a liquid at ambient pressures (Krestov 1991). 

For some compounds and multi-atom ions, it is possible to draw two or more equivalent arrangements of electrons. As an example, consider the following for sulfur dioxide ... 

Ar, Cs, Ga or other elements with energies between 0.5 and 10 keV), energy is deposited in the surface region of the sample by a collisional cascade. Some of the energy will return to the surface and stimulate the ejection of atoms, ions and multi-atomic clusters (figure Bl.25.8). In SIMS, secondary ions (positive or negative) are detected directly with a mass spectrometer. 

The effects on metal ion adsorption of ligands that can themselves adsorb strongly can be quite different from that described above. Many multi-atomic ligands can bond to oxide surfaces through atoms different from those they use to... 

Point defects are changes at atomistic levels, while line and volume defects are changes in stacking of planes or groups of atoms (molecules) m the structure. Note that the curangement (structure) of the individual atoms (ions) are not affected, only the method in which the structure units are assembled. Let us now examine each of these three types of defects in more detail, starting with the one-dimensional lattice defect amd then with the multi-dimensional defects. We will find that specific types have been found to be associated with each t3rpe of dimensional defect which have specific effects upon the stability of the solid structure. 

The homogeneous catalytic reaction occurs in the multi-component liquid phase P. The chemical constituents of the liquid phase include H, e", atoms, ions, and molecules etc. which are dissolved/solvated in one or more molecular or ionic solvents. Primary examples of the ions and molecules present are the dissolved organic and organometallic reagents, intermediates and products. By definition, all the molecular and ionic species involved directly in the homogeneous catalysis are soluble in this liquid phase P. The set of all dissolved species in the phase will be denoted by Eq. (3). 

In ICP-MS a multi-element tuning solution is applied for the mass calibration of mass spectra. Figure 6.3 shows the mass spectrum for phosphorus determination at m/z = 31. In this case, the mass calibration was performed with the aid of a solution of a phos-phorus/sulphur mixture. From the known masses of the isotopes of the atomic ions, the masses of the polyatomic ions occurring were determined and identified in accordance with the isobaric polyatomic ions (15N160+ and 14N16OH+). Mass accuracy is the deviation of experimental determined mass of an atomic, polyatomic, cluster, molecular or fragment ion from the exact mass of species expected. Polyatomic, cluster and molecular ions were calculated from the atomic masses (see Appendix I), the mass accuracy is usually presented in ppm. 

In fact, the converse is observed. The main features of the spectra of transition metal ions in solution are very similar to those for crystal lattices where the same donor atom is present as an anion. Further, the spectra differ little between solids provided the nearest-neighbour atom is unchanged, even if it is part of a multi-atom species and even if the symmetry of the crystal structure is low. The spectra of the first transition series carbonates, for example, are not markedly different from those of their oxides, nor from those of the ions in aqueous solution. In each case the nearest-neighbour atom is oxygen and six of these surround the metal atom in approximately octahedral positions. 

Semiclassical close-coupling description of electron transfer in multi-charged ion-atom collisions 121... 

Cluster ion ion formed by a multi-component atomic or molecular assembly of one or more ions with atoms, ions or molecules. 

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