With Nonmetals

Helium. Argon. The collision of PH3 with electronically excited He (2 S, 2 S) yields PHJ [1]. An ab initio MO calculation of the potential energy surface between PH3 and Ar suggested the formation of a van der Waals complex H3P- Ar with an internuclear distance r(P - Ar)= 3.75 A. An interaction energy of about -1.7 kJ/mol was calculated [2]. This value represents a lower limit because the basis set used for Ar was not optimal the actual interaction can be assumed to be stronger by 13 to 18% [3]. 

Hydrogen. The reaction of PH3 with atomic H proceeds with an intense, greenish yellow chemiluminescence and yields Hg and red phosphorus as stable products see Phosphor C, 1965, p. 35. The unstable intermediates PH2 [4 to 6], PH [4,7], P [8], and probably P2 [9] were identified spectroscopically the corresponding deuterated species were obtained with the reactant PD3. Bands of PHD were found in reactions with PH3/PD3 mixtures [5, 6]. The initial hydrogen abstraction from PH3 by H yields PH2 and can be used for preparative purposes 

A barrier height of 51 kJ/mol for the identity reaction H3P+H H + H2PH was estimated from the empirical Morse function of the H2P-H bond and geometrical parameters of the activated complex [14]. The reaction of recoil tritium atoms with PH3 yields PH2T and HT, see Section 1.3.1.5.1.5, p. 215. 

The formation of PH4 from PH3 and H in low-temperature matrices upon y irradiation is described in Section 1.4.1, p. 312. An ab initio MO calculation at the UHF/4-31G level predicted that PH3 and H individually are energetically more favorable than PH4 by 135 kJ/mol [15] see also Section 1.4.1, p. 313. The differences between the total energies of the reactants and the products for the formation of PHg from PH3 and H2 (+188 kJ/mol) or 2H (-246 kJ/mol) were obtained from ab initio MO calculations including configuration interactions but neglecting the differences in zero-point vibrational energies [16] see also Chapter 1.5, p. 321. 

Halogens. The reaction of PH3 with F atoms was investigated in flow reactors. The green emission observed in this reaction [17] is less intense than the one resulting from the reaction with F2 [18] (see below). The products are HF, which is vibrationally and rotationally excited [17, 19], PH2, PH, P, P2 as well as PF, PF2 [20], and PF3 [21]. Fluorinated products probably result from secondary reactions (P+F2, P2+F, etc.) [22]. The reaction of PH3 with F atoms is a convenient source of PH2 [10, 23, 24] see also Section 1.2.1.1, p. 48. 

---

Interstitial Compounds. Tungsten forms hard, refractory, and chemically stable interstitial compounds with nonmetals, particularly C, N, B, and Si. These compounds are used in cutting tools, stmctural elements of kilns, gas turbines, jet engines, sandblast nozzles, protective coatings, etc (see also Refractories Refractory coatings). 

Reaction with Nonmetals. Bromine oxidi2es sulfur and a number of its compounds. 

Table 2. Some Sulfide Compounds with Nonmetal—Metal Transitions...

The metals are found toward the left side of the periodic table and the nonmetals are at the right side. A compound containing elements from the opposite sides of the periodic table can be expected to form a conducting solution when dissolved in water. Notice from our examples that hydrogen reacts with nonmetals to form compounds that give conducting solutions in water. In this sense, hydrogen acts like a metallic element. 

The oxidation number of hydrogen is +1 in combination with nonmetals and —1 in combination with metals. 

Elements at the right of the p block have characteristically high electron affinities they tend to gain electrons to complete closed shells. Except for the metalloids tellurium and polonium, the members of Groups 16/VI and 17/VII are nonmetals (Fig. 1.62). They typically form molecular compounds with one another. They react with metals to form the anions in ionic compounds, and hence many of the minerals that surround us, such as limestone and granite, contain anions formed from non-metals, such as S2-, CO,2-, and S042-. Much of the metals industry is concerned with the problem of extracting metals from their combinations with nonmetals. 

The elements show increasing metallic character down the group (Table 14.6). Carbon has definite nonmetallic properties it forms covalent compounds with nonmetals and ionic compounds with metals. The oxides of carbon and silicon are acidic. Germanium is a typical metalloid in that it exhibits metallic or nonmetallic properties according to the other element present in the compound. Tin and, even more so, lead have definite metallic properties. However, even though tin is classified as a metal, it is not far from the metalloids in the periodic table, and it does have some amphoteric properties. For example, tin reacts with both hot concentrated hydrochloric acid and hot alkali ... 

Carbon forms ionic carbides with the metals of Groups 1 and 2, covalent carbides with nonmetals, and interstitial carbides with d-block metals. Silicon compounds are more reactive than carbon compounds. They can act as Lewis acids. 

Zi 5 Describe the reactions of the alkali metals with water and with nonmetals. 

B Aluminum forms an amphoteric oxide in which it has the oxidation state +3 therefore, aluminum is the element. 14.3B Hydrogen is a nonmetal and a diatomic gas at room temperature. It has an intermediate electronegativity (x — 2.2), so it forms covalent bonds with nonmetals and forms anions in combination with metals. In contrast, Group 1 elements are solid metals that have low electronegativities and form cations in combination with nonmetals. 

A common feature of metal atoms is that they are generally larger in size in comparison with nonmetal atoms. A characteristic of nonmetals is that their atoms have the ability to attach electrons to themselves, leading to the formation of anions. The opposite is true for the metals and as told they alter to cationic forms when their removable electrons leave them. 

In substitution reactions, hydrogen in its compounds with nonmetals often acts like a metal hence, it is listed among the metals in Table 7.1. 

Metals are located at the left side of the periodic table and therefore, in comparison with nonmetals, have (a) fewer outer shell electrons, (b) lower electronegativities, (c) more negative standard reduction potentials and (d) less endothermic ionization energies. 

Reacts with nonmetals to form ionic solid... 

When reacting with nonmetal, metal acts as a reducing agent... 

Finally, we need to consider compounds containing the nonmetal hydrogen. Remember that hydrogen is an exception. In simple binary compounds with nonmetals, we treat hydrogen as a metal. As a metal in the first column, it should have a +1 charge. Thus, H2S is hydrogen sulfide. 

Hydrogen is capable of forming compounds with all elements except the noble gases. In compounds with nonmetals, hydrogen usually behaves like a metal instead of a nonmetal. Therefore, when hydrogen combines with a nonmetal, it usually has a +1 oxidation number. When hydrogen combines with a metal, it usually has a —1 oxidation number. Hydrogen compounds with the transition metals are usually nonstoichiometric. Nonstoichiometric compounds have no definite formula. 

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. 

In naming compounds, don t confuse metal and nonmetal type binary compounds. Prefixes are used only with nonmetal types. 

The periodic table can give us many clues as to the type of reaction that is taking place. One general rule, covered in more detail in the Bonding chapter, is that nonmetals react with other nonmetals to form covalent compounds, and that metals react with nonmetals to... 

Metals react with nonmetals to form ionic bonds, and nonmetals react with other non-metals to form covalent bonds. 

As for all elements, the distribution of Mo in the environment depends critically on chemical speciation, including oxidation state (Bertine and Turekian 1973 Morford and Emerson 1999). However, Mo is somewhat unusual in both respects. In terms of ligand coordination. Mo is one of a small number of transition metals that commonly form oxy anions and coordinate only weakly with other environmentally common ligands such as Cl" or OH". Other such metals include Cr and W, which sit above and below Mo, respectively, in Group VI of the Periodic Table, as well as Tc, Re, Os and U. Hence, Mo chemistry has some analogies with these metals, as well as with nonmetals such as S, Se, P and As which also form oxyanions. 

Metals give up valence electrons (thus are electropositive) or share electrons with nonmetals. The most active metals are the ones on the left side of the table that have the least number of valence electrons. 

Sodium is the sixth most abundant of the Earths elements. Since it is a highly electropositive metal and so reactive with nonmetals, it is not found in its pure elemental form on Earth. Rather, it is found in numerous compounds in relatively abundant quantities. About 2.83% of the Earths crust consists of sodium in compounds. 

Zinc is a whitish metal with a bluish hue. As an electropositive metal, it readily gives up its two outer electrons located in the N shell as it combines with nonmetal elements. Zinc foil will ignite in moist air, and zinc shavings and powder react violently with acids. Zinc s melting point is 419.58°C, its boiling point is 907°C, and its density is 7.14 g/cm. ... 

Molybdenum is in the middle of the triad elements of group 6. These three metals (from periods 4, 5, and 6) are chromium, molybdenum, and tungsten, which, in their pure states, are relatively hard, but not as hard as iron. They are silvery-white as pure metals, and they have similar oxidation states. Their electronegativity is also similar—Cr = 1.6, Mo = 1.8, and W = 1.7—which is related to their reactivity with nonmetals. 

Selenium burns with a blue flame that produces selenium dioxide (SeO ). Selenium will react with most metals as well as with nonmetals, including the elements in the halogen group... 

Following are two examples of polonium s +2 and +4 oxidation states, in which the element mostly forms compounds with nonmetals. 

Bromine combines with nonmetals according to the lowest positive oxidation state of the nonmetal. For example,... 

Neptunium has an affinity for combining with nonmetals (as do all transuranic elements) such as oxygen, the halogens, sulfur, and carbon. 

As with most other transuranic elements of the actinide series, fermium has an oxidation state of +3, as well as possibly a +2 oxidation state. Thus, this ion can combine with nonmetals, such as oxygen and the halogens, as do many of the other elements in this series. Two examples follow ... 

---