Charge on the ion

The kinetic or translational energy of the ions is equal to the work done on moving the charged species through the potential, V, i.e., l/2mjVi = zV and l/2m2V2 = zV, where z is the charge on the ions and Vj, V2 are their final velocities. From this, we obtain Equations 33.1 and 33.2. 

A mass spectrometer measures mass-to-charge ratio (m/z) and, often, the charge on the ion is unity, so that m/z = m/1 = m. Thus, a mass spectrometer can be used to measure mass. 

Dissociative charge transfer. Occurs when an ion/molecule reaction takes place in which the charge on the ion is transferred to the neutral species. The new ion then dissociates to one or more fragment ions. 

MS", application of successive mass spectrometric measurements n of them), particularly in linked scanning of m/z, which is the ratio of the mass (m) of an ion and the number of charges (z) on it. Older publications used m/e, but as e is the actual charge on an electron and not the number of charges on the ion, the use of m/e was abandoned, m/z. mass-to-charge ratio, a measure of molecular mass PDB. PeeDee Belemnite (a carbon isotope standard see VPDB)... 

For each of the alkaline earths, calculate the ratio Et/E. Account for the results in terms of the charges on the ions formed in the two ionization steps. 

Electrical neutrality in the solution requires that the total charge around the ion be balanced by the charge on the ion. This condition is expressed by the... 

First check to see whether the compounds are ionic or molecular. Many compounds that contain a metal are ionic. Write the symbol of the metal first, followed by the symbol of the nonmetal. The charges on the ions are determined as shown in Examples C.l and C.2. Subscripts are chosen to balance charges. Compounds of two nonmetals are normally molecular. Write their formulas by listing the symbols of the elements in the same order as in the name, with subscripts corresponding to the Greek prefixes used. 

The only directly measurable variable in this equation is m/z and therefore, in order to determine M, we must be able to determine the number of charges on the ion whose mjz value is known. This may be carried out by considering the relationship given in equation (4.2) for two adjacent ions in the spectrum. For the first ion, whose measured m/z value is mi we may write the following ... 

Since m2 < mi (by definition), H2 must be greater than ni and it is not unreasonable to assume that n2 = ni - -1, i.e. the number of charges on the ions differs by one (this assumption is borne out by the validity of the expression when subsequently applied to all electrospray spectra). We may therefore write the following equation, containing a single unknown i, which may be solved readily ... 

These figures clearly demonstrate that the number of charges on the ion does not affect the resolution required to separate the ions in the molecular ion region. 

A useful feature of formal charges is that the sum of the formal charges on all atoms equals the charge of the species. For a neutral molecule, the sum of the formal charges must be zero. For a cation or anion, the sum of the formal charges equals the charge on the ion. 

As a result of these electrostatic effects aqueous solutions of electrolytes behave in a way that is non-ideal. This non-ideality has been accounted for successfully in dilute solutions by application of the Debye-Huckel theory, which introduces the concept of ionic activity. The Debye-Huckel Umiting law states that the mean ionic activity coefficient y+ can be related to the charges on the ions, and z, by the equation... 

---