Monoatomic ion

The kind of bond between neighboring atoms also has to be considered. For instance, the coordination number for a chlorine atom in the CC14 molecule is 1 when only the covalently bonded C atom is counted, but it is 4 (1 C + 3 Cl) when all atoms in contact are counted. In the case of molecules one will tend to count only covalently bonded atoms as coordinated atoms. In the case of crystals consisting of monoatomic ions usually only the anions immediately adjacent to a cation and the cations immediately adjacent to an anion are considered, even when there are contacts between anions and anions or between cations and cations. In this way, an I- ion in Lil (NaCl type) is assigned the coordination number 6, whereas it is 18 when the 12 I- ions with which it is also in contact are included. In case of doubt, one should always specify exactly what is to be included in the coordination sphere. 

Fig. 2.6. Oxidation state patterns for the elements from potassium to zinc, compiled from a survey of aqueous monoatomic ions and aqueous oxyions, stoichiometric oxides, halides and other simple salts.

The secondary ion yield depends both on the energy and the nature of the primary ions. It has been demonstrated that the use of clusters instead of monoatomic ions improves the secondary yield. Classical primary ions, like Ga+ and Cs+, are increasingly replaced by Au3+, Bi3+ or C60+ which has permitted great progress in organic ToF-SIMS studies [Kollmer 2004, Touboul et al. 2004, Winograd 2005]. 

These succesive isoelectronic processes may be represented, for the inmersion of a charged monoatomic ion A+ say, by the cycle described in Figure 1. Where X is an auxiliary isoelectronic neutral system. According to the cycle shown in Figure 1, we may write the insertion energy variation as follows ... 

ICP is an emission technique, which means that it does not use a light source. The light measured is the light emitted by the atoms and monoatomic ions in the atomizer. The ICP atomizer is an extremely hot plasma, which is a high-temperature ionized gas composed of electrons and positive ions confined by a magnetic held. The extremely high temperature means that the atoms and monoatomic ions undergo sufficient excitation (and de-excitation) such that relatively intense emission spectra result. The sample is drawn in with a vacuum mechanism that will be described. The intensity of an emission line is measured and related to concentration. 

ICP Light emitted by atoms and monoatomic ions in an inductively coupled plasma is measured A popular technique useful over a broad concentration range multielement analysis is possible instruments are costly... 

The oxidation number of an element in its elemental form (i.e., H2, Au, Ag, N2) is zero. The oxidation number of a monoatomic ion is equal to the charge on the ion. The oxidation number of Mg2+ is +2. Note that the charge is written with number first, then sign for oxidation numbers it is sign, then number. 

Ionic bonding may also involve polyatomic ions. The polyatomic ion(s) simply replace(s) one or both of the monoatomic ions. 

For monoatomic ions, the RE has the same numerical value as the IE of the neutral for diatomic or polyatomic species differences due to storage of energy in internal modes or electronic excitation may occur. Ionization of the analyte via CE is effected if [49]... 

Activity coefficients can be determined by experimental observations. Since they are functions of ionic strength, temperature and pressure, marine scientists typically estimate values at the environmental conditions of interest from semi-empirical equations. In dilute solutions, the activity coefficient of a monoatomic ion can be calculated from the Debye-Hiickel equation ... 

Table 5.3 Various Expressions for the Caiouiation of Aotivity Coefficients for Monoatomic ions. ...

Argon plasmas are used in optical emission spectrometry to atomise and ionise elements leading to the emission of characteristic spectral lines. Hence, a plasma torch (7-8 000 K) can be used for ionisation in mass spectrometry. Ions produced in the plasma are introduced into the mass analyser through a small orifice (called a skimmer) placed in the axial direction. Because the mass spectrometer is operated under a vacuum, the ions are sucked into the mass analyser through the skimmer. An aqueous solution of the sample can be aspirated into the plasma or, alternatively, the plasma can be placed at the exit of a gas chromatograph (e.g. speciation of organo-metallic compounds by GC/ICP-MS). Since all chemical bonds are broken in the plasma, the only accessible information is that concerning the concentration of monoatomic ions (Fig. 16.19). 

Monoatomic ions have an oxidation number equal to the charge of the ion,... 

A wide variety of chemical structures, from simple monoatomic ions and molecular ions to complex molecules. 

The An4+ cations are characteristic for actinides from Th through Cf (U4+ is readily oxidized) and in the case of Th are the only one existing in solution. Their acidity decreases in the order Pa4+ U4+ > Pu4+ > Np4+ > Th4+ [282]. The monoatomic ions exist only in very dilute solutions and tend to form polynuclear species when concentration is increased (5.47) ... 

I. A. Topol, G. J. Tawa, S. K. Burt and A. A. Rashin, On the structure and thermodynamics of solvated monoatomic ions using a hybrid solvation model, J. Chem. Phys. Ill (1999) 10998-11014. 

An important difference between halogens and other donor atoms is that the former present themselves only as monoatomic, and monovalent, ions, while the latter are present in a great variety of ligands. Among these are only in few cases, and under exceptional conditions, the simple monoatomic ions (such as S2 at pH > 13, (14, 15). The environment of a certain donor atom is very different in different types of ligands which may result in considerable modifications of its capacity for covalent bonding. To assess such influences, it is necessary to compare complex... 

Monoatomic ions = Ions with only one atom (Na, CP...). 

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