Compounds and Complex Ions

Our goal in this chapter is to familiarize you with some properties of the elements, as well as the periodic trends that you can observe in these properties. You might want to review briefly the periodic trends we discussed in Chapter 8. We will also discuss coordination compounds and complex ions. Again— Practice, Practice, Practice. 

All the remaining halogens have unfilled d orbitals available and the covalency of the element can be expanded. Compounds and complex ions are formed both with other halogens and with oxygen in which the halogen can achieve a formal oxidation state as high as + 7. for example chlorine has formal oxidation states of +1 in the chlorate(I) anion CIO + 5 in the chlorate(V) anion CIO 3, and + 7 in the chlorate(VII) anion CIO4. ... 

Although few authors have said so in as many words, coordination compounds and complex ions are at the heart of every stage of the cycle. These include minerals, species in fluids ranging from aqueous solutions to silicate melts, complexes in sediments and asphalts, and chelates intimately involved in life processes and their decomposition products. 

The more common +2 oxidation state is found in the blue aqueous ion, Cu(H20)62+, and in numerous solid compounds and complex ions. The addition... 

Pearson s Hard-Soft-Acid-Base (HSAB) priciple is that hard add-base combinations form readily and are generally ionic compounds. The other group of stable compounds and complex ions involves the interaction between soft acid and soft bases. For these, the bonding is primarily covalent with interpenetrating orbitals. The combinations hard acid with soft base, or vice versa, have little stability. 

The series of ten elements from scandium to zinc is known as the First Transition Series. Most of these show distinctive properties such as variable valency, coloured compounds, and complex ion formation. 

All of the elements can be found naturally as ions, most often as 2- ions (except for Po). Oxidation states of -i2, -i4, and +6 also can be fonnd for members S - Po when combined with O, F, or Cl. The difference in oxidation states can be explained by the electronic structure of the elements. Oxygen is able to use only s and p orbitals for bonding. The larger members of the group use d orbitals in the hybridization and thus can participate in the use of an expanded octet. This is shown in compounds and complex ions such as SOF4, SF4, Se04 -, TeFg —. 

Notes on the addition reactions of nitric oxide. Nitric oxide is an odd molecule, with an odd number of electrons. Probably because of this fact it is unusually active in forming coordination compounds. Examples of such coordination compounds and complex ions are (FeNO)++, [Co(NH3)6NO]++, CuNOCls-, FeNOCls, AINOCI3, Fe(CN)BNO", and the nitrosyl carbonyls, such as Co(CO)3NO. Many of these complexes are unstable and decompose on heating. They appear to be formed by the donation of either one or three electrons from the NO molecule thus in the nitroprusside ion, Fe(CN)5NO , produced by the action of nitric acid on a ferrocyanide, the nitric oxide is considered to contribute three electrons to the iron atom, leaving the latter in the ferrous rather than the ferric condition. Likewise the existence... 

Define inorganic complex, coordination compound, and complex ion. 

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