Oxidation numbers minimum

K.22 (a) Determine and tabulate the maximum (most positive) and minimum (most negative) oxidation numbers of the elements in the first seven main groups. Hint ... 

Maximum oxidation numbers are often found in the oxoanion with the most oxygen atoms. For minimum oxidation numbers, consult Fig. C.6. (b) Describe anv patterns you see in the data. 

The minimum oxidation number of any nonmetallic atom is equal to its group number minus 8. The minimum oxidation number of any metallic atom is 0. 

S is in periodic group VIA, and so its maximum oxidation number is +6 and its minimum oxidation number is 6 - 8 = -2. It also has an oxidation number of 0 when it is a free element. 

The rules above gave maximum and minimum oxidation numbers, but those might not be the only oxidation numbers or even the most important oxidation numbers for an element. Elements of the last six groups of the periodic table for example may have several oxidation numbers in their compounds, most of which vary from each other in steps of 2. For example, the major oxidation states of chlorine in its compounds are -1, +1, +3, +5, and +7. The transition metals have oxidation numbers that may vary from each other in steps of 1. The inner transition elements mostly form oxidation states of + 3, but the first part of the actinoid series acts more like transition elements and the elements have... 

Table 4.2. Lewis-like oxidation numbers (n07L), formal d count, metal electron configuration (eep, Chp) and minimum and maximum coordination numbers (ncs) for low-spin normal-valent compounds of group 6-11 transition metals...

For metals and noble gases Minimum oxidation number... 

The minimum oxidation number of the metallic elements and the noble gases is generally zero and that for hydrogen is -1. The minimum oxidation number of other nonmetallic elements is equal to the classical group number of the element minus 8. 

What is the minimum oxidation number of nitrogen in any of its compounds ... 

The maximum oxidation number of sulfur is +6, equal to its group number. Sulfur also has the oxidation state 0 when it is not combined and a minimum oxidation state of 6 - 8 = -2. (Sulfur can also have oxidation states +4 and + 2, not covered by the rules given so far.)... 

Oxidation number is a periodic property. For example, for most elements the maximum oxidation number is equal to the classical group number, and the minimum oxidation number for nonmetals other than hydrogen is the group number minus 8. 

What are the maximum and minimum oxidation numbers of hydrogen ... 

What are the maximum and minimum oxidation numbers in any of their compounds for (a) sulfur, (b) fluorine, (c) phosphorus, and (d) lead ... 

Nearly all binary molecular compormds involve two nonmetals bonded together. Although many nonmetals can exhibit different oxidation numbers, their oxidation numbers are not properly indicated by Roman numerals or suffixes. Instead, elemental proportions in binary covalent compounds are indicated by using a prefix system for both elements. The Greek and Latin prefixes for one through ten are mono, di, tri, tetra, penta, hexa, hepta, octa, nona, and deca. The prefix mono- is omitted for both elements except in the common name for CO, carbon monoxide. We use the minimum number of prefixes needed to name a compound unambiguously. The final a in a prefix is omitted when the nonmetal stem begins with the letter o we write heptoxide, not heptaoxide. ... 

The integer solutions for the oxidation numbers of iron in Prussian blue are shown in Table 13.4. Indeed, we observe in nature the oxidation numbers, whose difference is a minimum. Iron arises by the way mainly in the oxidation numbers 0, 2.3, 6. So far known, oxidation numbers are from —2 to 3-6, e.g., FeH2(CO)4. 

The oxidation numbers of the C atoms in CH4 and CCI4 are -4 and 4-4 respectively. The oxidation number of the central carbon atom in C(CH3)4 is zero. Minimum energy rupture of a bond in CH4 or CCI4 or a C-C bond in C(CH3)4 yields neutral, radical species. These bonds are therefore classified as homolytic bonds. We shall refer to the number of (single) homolytic bonds that an atom forms, as the valency of the atom. The central atoms in the compounds EH4, E(CH3)4 and ECI4 are all tetravalent. 

A number of gases may decompose (self-react) and propagate flames in the absence of any oxidant provided that they are above minimum conditions of pressure, temperature, and pipe diameter. Common examples are acetylene, ethylene oxide, and ethylene. Some, like acetylene, can decompose in a detonative manner, while ethylene cannot detonate in the absence of an oxidant, whatever the run-up length (CCPS 1993). Thus, detonation arresters must be used for acetylene, but deflagration arresters may be used for ethylene, even for in-line applications. 

As with all determinations of thermodynamic stability, we comihehce by defining all stable phases possible, and their standard, chemical, potentials. For inost, metals there are many such phases, including oxides, hydroxides and dissolved ions. For brevity, here, only the minimum number of phases is Considered. The siriiplest system is a metal, ilf, which can oxidise lo form a stable dissolved pro,duct, (qorrpsipn), or to form a stable oxide MO (passivation), lit aqueous environments thfbe equilibria Can thereby be... 

The Fe—O distances in hematite are 1.99 and 2.06 A. The (Mn,Fe)—O distances in bixbyite are expected to be the same in case that (Mn, Fe) has the coordination number 6, and slightly smaller, perhaps 1.90 A, for coordination number 4. The radius of 0= is 1.40 A, and the average O—O distance in oxide crystals has about twice this value. When coordinated polyhedra share edges the O—O distance is decreased to a minimum value of 2.50 A, shown by shared edges in rutile, anatase, brookite, corundum, hydrargillite, mica, chlorite, and other crystals. Our experience with complex ionic crystals leads us to believe that we may... 

Lowering the temperature of the reaction would certainly decrease the rate of acetal hydrolysis and thereby partially remove one of the causes of overoxidation. This would simultaneously decrease the rate of oxidation by periodate. Although no comprehensive study of the effect of temperature on oxidation rates has been made, the number of reactions successfully dealt with in the temperature range of 0 to 6°31 39 78 113 126 130 i33, i64, us, 203,210,266,267 indicates that lowered temperatures do not affect the rates unfavorably. In order to obtain the maximum of selective oxidation and the minimum of overoxidation, periodate oxidations should be performed at as low a temperature as is practicable in relation to the solvent system used and the solubility of the reactants therein. 

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