Oxidation states of halogens

Oxidation State of Halogen Fluorine Chlorine Bromine Iodine General Name of Acids General Name of Salts... 

Oxidation State of Halogen Formula of Acid Acid Name... 

EXAMPLE 22.6 Deteraiining the Oxidation State of Halogens in Compounds... 

Oxidation State of Halogen Chlorine Bromine Iodine... 

More detailed consideration of these various equilibria and other redox reactions of the halogen oxoacids will be found under the separate headings below. As expected, the rates of redox reactions of the halogen oxyanions will depend, sometimes crucially, on the precise conditions used. However, as a very broad generalization, they tend to become progressively faster as the oxidation state of the halogen decreases, i.e. ... 

The strengths of the monobasic acids increase rapidly with increase in oxidation state of the halogen in accordance with Pauling s rules (p. 50). For example, approximate values of pKa are HOCl 7.52, HOCIO 1.94, HOCIO2 - 3, HOCIO3 — 10. The pXa values of related acids increase in the sequence Cl < Br < I. 

Many of the compounds in higher oxidation states are reactive, and for moisture-sensitive solids that cannot be crystallized, some of the bond lengths quoted in Table 2.1 are from EXAFS measurements [24], Raman spectroscopy is likewise well suited to studying such reactive compounds, and vibrational data for halometallates are given in Table 2.2 trends illustrated include the decrease in frequency as the oxidation state of the metal decreases, and similarly a decrease in vibrational frequency, for a given oxidation state, with increasing mass of the halogen. 

As expected, there is a shift to lower frequency as the oxidation state of the metal decreases and as the mass of the halogen increases. 

An important source of reference is another excellent review by Stern [844] this one is concerned with the high temperature properties of oxy-halides. The following general trends are found in salts containing an XO anion (X = Cl, Br and I) there are variations in stabilities in the sequences (i) (X =) Cl > Br > I for halogens in the same oxidation state, and (ii) XO4 > XOJ > XO2 > XCT for the different oxidation states of a particular halogen. 

Oxidation of these complexes with halogen results in the oxidation of the ligand, yielding a thiuram disulfide complex X2M(R4tds), leaving the oxidation state of the metal unchanged (99,100,161). 

Cl has an oxidation state of - I (rule 7). I has an oxidation number of +3 (rule 1). I is not -1 because it is combined with a halogen higher in the periodic table. 

All the remaining halogens have unfilled d orbitals available and the covalency of the element can be expanded. Compounds and complex ions are formed both with other halogens and with oxygen in which the halogen can achieve a formal oxidation state as high as + 7. for example chlorine has formal oxidation states of +1 in the chlorate(I) anion CIO + 5 in the chlorate(V) anion CIO 3, and + 7 in the chlorate(VII) anion CIO4. ... 

Niobium in its +5 oxidation state forms both oxygen and halogen compounds (Niobium in oxidation states of+2, +3 and +4 also forms compounds—for example, niobium(ll) dioxide and niobium(IV) tetraoxide) ... 

When combining with the halogens, the oxidation states of +2 or +4 for palladium are used. 

As a nonmetal, chlorine exists as a greenish-yellow gas that is corrosive and toxic at room temperatures. As a halogen, chlorine is not found in the elemental (atomic) state but forms diatomic gas molecules (Cl j). As a very active negative ion with the oxidation state of —1, chlorine forms bonds with most metals found in groups I and II. 

Dysprosium has an oxidation state of +3, which forms the Dy metallic ion that is hmited to a small group of compounds. A general example that demonstrates how the ion of dysprosium combines with halogen anions follows Dy + 3C1 — DyCl. ... 

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