Oxidation-reduction reactions nonmetals

Oxidation-reduction reactions may affect the mobility of metal ions by changing the oxidation state. The environmental factors of pH and Eh (oxidation-reduction potential) strongly affect all the processes discussed above. For example, the type and number of molecular and ionic species of metals change with a change in pH (see Figures 20.5-20.7). A number of metals and nonmetals (As, Be, Cr, Cu, Fe, Ni, Se, V, Zn) are more mobile under anaerobic conditions than aerobic conditions, all other factors being equal.104 Additionally, the high salinity of deep-well injection zones increases the complexity of the equilibrium chemistry of heavy metals.106... 

Metals react with nonmetals. These reactions are oxidation-reduction reactions. (See Chapters 4 and 18). Oxidation of the metal occurs in conjunction with reduction of the nonmetal. In most cases, only simple compounds will form. For example, oxygen, 02, reacts with nearly all metals to form oxides (compounds containing O2-). Exceptions are the reaction with sodium where sodium peroxide, Na202, forms and the reaction with potassium, rubidium, and cesium where the superoxides, K02, Rb02, and Cs02 form. 

Chemically, nonmetals are usually the opposite of metals. The nonmetallic nature will increase towards the top of any column and toward the right in any row on the periodic table. Most nonmetal oxides are acid anhydrides. When added to water, they will form acids. A few nonmetals oxides, most notably CO and NO, do not react. Nonmetal oxides that do not react are neutral oxides. The reaction of a nonmetal oxide with water is not an oxidation-reduction reaction. The acid that forms will have the nonmetal in the same oxidation state as in the reacting oxide. The main exception to this is N02, which undergoes an oxidation-reduction (disproportionation) reaction to produce HN03 and NO. When a nonmetal can form more than one oxide, the higher the oxidation number of the nonmetal, the stronger the acid it forms. 

Chapter 13. For now we will be satisfied with some general guidelines to help us keep track of electrons in oxidation-reduction reactions. The nonmetals with the highest attraction for shared electrons are in the upper right-hand corner of the periodic table. They are fluorine, oxygen, nitrogen, and chlorine. The relative ability of these atoms to attract shared electrons is... 

This is an oxidation-reduction reaction in which chlorine oxidizes sodium to form Na+ and Cl- ions. In the reactions between metals and nonmetals it is typical for the nonmetal to behave as the oxidizing agent and the metal to behave as the reducing agent, as shown by the following reactions ... 

In combination reactions, two substances, either elements or compounds, react to produce a single compotmd. One type of combination reaction involves two elements. Most metals react with most nonmetals to form ionic compounds. The products can be predicted from the charges expected for cations of the metal and anions of the nonmetal. For example, the product of the reaction between aluminum and bromine can be predicted from the following charges 3-1- for aluminum ion and 1— for bromide ion. Since there is a change in the oxidation numbers of the elements, this type of reaction is an oxidation-reduction reaction ... 

Thus the reaction of a metal with a nonmetal to form an ionic compound involves the transfer of one or more electrons from the metal (which forms a cation) to the nonmetal (which forms an anion). This tendency to transfer electrons from metals to nonmetals is the third driving force for reactions that we listed in Section 8.1. A reaction that involves a transfer of electrons is called an oxidation-reduction reaction. 

Why can metal-nonmetal reactions always be assumed to be oxidation-reduction reactions ... 

There are many examples of oxidation-reduction reactions in which a metal reacts with a nonmetal to form an ionic compound. Consider the reaction of magnesium metal with oxygen,... 

So far we have emphasized electron transfer (oxidation-reduction) reactions that involve a metal and a nonmetal. Electron transfer reactions can also take place between two nonmetals. We will not discuss these reactions in detail here. All we will say at this point is that one sure sign of an oxidation-reduction reaction between nonmetals is the presence of oxygen, 0 g), as a reactant or product. In fact, oxidation got its name from oxygen. Thus the reactions... 

When a metal reacts with a nonmetal, an ionic compound is formed. The ions are formed when the metal transfers one or more electrons to the nonmetal, the metal atom becoming a cation and the nonmetal atom becoming an anion. Therefore, a metal-nonmetal reaction can always be assumed to be an oxidation-reduction reaction, which involves electron transfer. 

Two nonmetals can also undergo an oxidation-reduction reaction. 

Reactions between metals and nonmetals involve a transfer of electrons from the metal to the nonmetal which is called an oxidation-reduction reaction. 

Reactions Between Nonmetals Although we can identify reactions between metals and nonmetals as redox reactions, it is more difficult to decide whether a given reaction between nonmetals is a redox reaction. In fact, many of fhe mosf significanf redox reactions involve only nonmetals. For example, combustion reactions such as methane burning in oxygen are oxidation-reduction reactions. 

For each of the following oxidation-reduction reactions of metals and nonmetals, identify the element that is oxidized and the element that is being reduced. 

Two nonmetals can also undergo an oxidation-reduction reaction. At this point we can recognize these cases only by looking for O2 as a reactant or product. When two nonmetals react, the compound formed is not ionic. 

OBJECTIVE To learn about metal-nonmetal oxidation-reduction reactions. 

Reduction is the gain of electrons, and in the conversion of chlorine to chloride ions (Cl ) in this reaction, each chlorine atom has been reduced by the gain of a single electron. Reactions in which one reactant is oxidized and another is reduced are known as oxidation-reduction reactions, usually referred to as redox reactions. For example, every reaction in which a metallic element combines with a nonmetallic element is a redox reaction in which the metal is oxidized and the nonmetal is reduced. 

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