Group 16 elements sulfide ions

The charges on the cations are equal to the numbers of valence electrons originally in the atoms, and the charges on the anions are equal to 8 minus the number of valence electrons. The numbers of valence electrons for these elements are easily determined from their periodic group numbers. The two lithium ions in the compound of part (c) are not bonded to each other because they are both positive and repel each other. They should not be written with a subsaipt (except in the formula for the compound, Li2S, in which they are both bonded to the sulfide ion). If we want to show that two hthium ions are present, we must write 2 Li. ... 

The second group of metal ions consists of those elements whose sulfides are so insoluble that H2S in 0.3 M HCl will precipitate them ... 

The first group of ions consists of those precipitated by HCI. The separation of the next two groups is based on the differences in solubilities of the metal sulfides.The fourth group consists of ions of the alkaline earth elements, which are precipitated as carbonates or phosphates.The final group of ions is in the filtrate after these precipitations. 

At room temperature bismuthine rapidly decomposes into its elements. The rate of decomposition increases markedly at higher temperatures (8). Bismuthine decomposes when bubbled through silver nitrate or alkafl solutions but is unaffected by light, hydrogen sulfide, or 4 sulfuric acid solution. There is no evidence for the formation of BiH, though the phenyl derivative, (C H BU, is known. The existence of BiH would not be anticipated on the basis of the trend found with other Group 15 (V) "onium" ions. 

A detailed discussion of individual halides is given under the chemistry of each particular element. This section deals with more general aspects of the halides as a class of compound and will consider, in turn, general preparative routes, structure and bonding. For reasons outlined on p. 805, fluorides tend to differ from the other halides either in their method of synthesis, their structure or their bond-type. For example, the fluoride ion is the smallest and least polarizable of all anions and fluorides frequently adopt 3D ionic structures typical of oxides. By contrast, chlorides, bromides and iodides are larger and more polarizable and frequently adopt mutually similar layer-lattices or chain structures (cf. sulfides). Numerous examples of this dichotomy can be found in other chapters and in several general references.Because of this it is convenient to discuss fluorides as a group first, and then the other halides. 

Am. In each ease, the answer is BuS. Part (ft) gives the ions and their charges, and so is perhaps easiest to answer. Part (know that periodic group IIA elements always form 2-t- ions in all their compounds and that sulfur forms a 2- ion in its compounds with metals. It is also necessary to remember that the metal is named first. In part (< ). the fact that there is only one compound of these two elements is deduced by the fact that the barium is stated with no Roman numeral, and that sulfide is a specific ion with a specific (2-) charge. 

Sulfide compounds are formed by all of the Group IVA elements, and lead is found as the sulfide in its principle ore galena that has Pb2+ and S2 ions in a sodium chloride lattice (see Chapter 3). A chain structure is shown by SiS2 in which each Si is surrounded by four S atoms in an approximately tetrahedral environment ... 

Those in which the metal atoms are in somewhat higher oxidation states (+2 to +4) and the ligands are typically halide, sulfide, or oxide ions and some others of the same ilk as those in mononuclear Werner complexes. Clusters of this type are most common among the early transition elements, groups 5-7. 

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