The Group 5A Elements

Salts containing Bi3+ or Sb3+ ions, such as Sb2(S04)3 and Bi(N03)3, are quite common. When these salts are dissolved in water, the resulting hydrated cations are very acidic. For example, the reaction of the BiJ+ ion with water can be represented as 

The Group 5A elements can form molecules or ions that involve three, five, or six covalent bonds to the Group 5A atom. Examples involving three 

TABLE 19.1 Selected Physical Properties, Sources, and Methods of Preparation for the Group 5A Elements  

Phosphorus 2.2 Phosphate rock [Ca3(P04)2], fluorapatite [Cas(P04)3F] 2Ca3(P04)2 + 6Si02 6CaSi03 + P4Ok) P4O10 + 10C 4P + 10CO 

Arsenic 2.2 Arsenopyrite (Fe3As2, FeS) Heating arsenopyrite in the absence of air 

Bismuth and antimony tend to be metallic, readily losing electrons to form cations. Although these elements have five valence electrons, so much energy is required to remove all five that no ionic compounds containing Bi or Sb ions are known. 

Antimony 2.1 Stibnite (Sb2S3) Roasting Sb2S3 in air to form Sb203 and then reduction with carbon 

Bismuth 2.0 Bismite (Bi203), bismuth glance (61283) Roasting 61283 in air to form Bi203 and then reduction with carbon 

The Group 5A elements can form molecules or ions that involve three, five, or six covalent bonds to the Group 5A atom. Examples involving three single bonds are NH3, PH3, NF3, and ASCI3. Each of these molecules has a lone pair of electrons (and thus can behave as a Lewis base) and a pyramidal shape as predicted by the VSEPR model (see Fig. 20.8). 

All the Group 5A elements except nitrogen can form molecules with five covaleut bonds (of general formula MX5). Nitrogeu cannot form such molecules because of its small size. The MX5 molecules have a trigonal bipyramidal shape (see Fig. 20.9) 

Unless otherwise noted, all art on this page is Cengage Learning 2014. 

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The reason for such a behaviour of arsenic acid is that arsenic is a member of the group 5A elements in the periodic table. Phosphorus and antimony are also group 5 elements and are known to be chemically similar to arsenic. On this basis [8,9], the antimonic acids were found to be poor cassiterite collectors. The alkyl phosphonic acids were not selective collectors. The ethylphenylene phosphonic acid was found to produce similar or better results compared to /7-tolyl arsonic acid. The structural formula for phosphonic acid (Figure 21.5) is similar to that of /7-tolyl arsonic acid but arsenic was replaced with phosphoms. The styrene phosphonic acid radicals are C6H5-CH-CH and p-ethylphenylene CH3-CH2-C6H4. 

Which explanation is incorrect regarding the group 5A elements. 

Look at their positions in the periodic table. The group 4A element germanium has four valence-shell electrons and thus has four relatively low ionization energies, whereas the group 5A element arsenic has five valence-shell electrons and has five low ionization energies. 

The valence electron configuration of the group 5A elements is ns2 np3. They exhibit a maximum oxidation state of +5 in compounds such as HNO3 and PF5/ in which they share all five valence electrons with a more electronegative element. They show a minimum oxidation state of —3 in compounds such as NH3 and PH3/ where they share three valence electrons with a less electronegative element. The —3 state also occurs in ionic compounds such as Li3N and Mg3N2, which contain the N3- anion. 

Identify the group 5A element(s) that best fits each of the following descriptions ... 

Give the chemical formula for each of the following compounds, and indicate the oxidation state of the group 5A element ... 

The two heaviest members of Group 6A can lose electrons to form cations. Although they do not lose all six valence electrons because of the high energies that would be required, tellurium and polonium appear to exhibit some chemistry involving their 4+ cations. However, the chemistry of these Group 6A cations is much more limited than that of the Group 5A elements bismuth and antimony. 

FIGURE 8.18 The Group 5A elements. Molecular nitrogen is a colorless, odorless gas. 

The Group 2A Elements The Group 3A Elements The Group 4A Elements The Group 5A Elements The Chemistry of Nitrogen... 

The Group 5A element in Table 20.13 that should have the most metallic character. 

The electron affinities of the group 5A elements are also interesting. Because these elements have half-filled p subsheUs, the added electron must be put in an orbital that is already occupied, resulting in larger electron—electron repulsions. Consequently, these elements have electron affinities that are either positive (N) or less negative than the electron affinities of their neighbors to the left (P, As, Sb). RecaU that in Section 7.4 we saw a discontinuity in the trends for first ionization energy for the same reason. 

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