General Introduction of Scandium, Titanium.

Introduction of Scandium

These four elements are sometimes grouped with the 14 lanthanides and called collectively the ‘rare earth’. This is a misnomer because the scandium group are the d-block element and the lanthanide is f-block elements. In addition, the scandium group is by no means rare ,except or actinium which is radioactive. The trend in properties in the family Sc, Y, La, and Ac are quite regular, and similar to the trend in groups 1 and 2. There are few important industrial uses of the elements or their compounds apart from Mischmetal, which is used in the metallurgical industrials.

Oxidation state.

The elements always exist in the oxidation state (+III), and occur as M3+ ions. The formation of M3+ requires the removal of the two s and one p electron. Thus the ions have a d0 configuration, and d-d spectra are impossible. As a result, the ions, and their configuration, and d-spectra are diamagnetic. The sum of the first three ionisation energy for scandium is a little less than the sum for aluminium. The properties of scandium are similar in some ways to those of aluminium.

The introduction of Titanium.

Titanium is the generally important element. Vast quantities of TiO₂ are used as a pigment and filler, and Ti metal is important for its strength, low density, and corrosion resistance. TiCl₃ is important as a Ziegler-Natta catalyst for making polyethene and other polymers. Zirconium is used to make the cladding for fuel rods in water cooled nuclear reaction. Hafnium is used to make control rods for certain reactors.

The introduction of Vanadium.

Vanadium is commercially important as the alloy ferrovanadium which to make alloy steels. V₂O₅ is well known and is an important catalyst, and V metal is also used as the catalyst. The vanates have an extensive solution chemistry. Niobium and tantalum are only used in small quantities. However, there is great theoretical interest in the cluster compounds they form in their low oxidation states.

The introduction of Chromium group.

Chromium metal is produced on a large scale, and is extensively in ferrous and non-ferrous alloys, and for electroplating. The metals molybdenum and tungsten are produced in appreciable amounts. Sodium dichromate is also used in large amount. CrO₃ and Cr₂O₃ are both used commercially.

Tungsten and Molybdate ions from extensive series of iso and hetero polyacid. Chromium II acetate has an unusual structure with a quadruple bond. The lower halide MOX₂ and WX₂ form interesting cluster compounds based on the octahedral [M6X8]⁴⁺ metal cluster. MO is important in the fixation of dinitrogen.

The introduction of Manganese.

Manganese is produced in very large amounts, most of which is used in the steel industry. Large quantities of MnO₂ are also produced and are used mainly for making ‘dry’ batteries and in the brick industry. KMnO₄ is an important oxidising agent. Mn(+III) forms a basic acetate with an unusual structure. Mn is biologically important and is necessary for photosynthesis. The elements technetium and rhenium are rarely encountered. They differ from manganese in that they have little cationic chemistry, their high oxidation state is much more stable, and the oxidation state (+II), (+III), and (+IV) from cluster compounds and compounds with metal-metal bonds.

The introduction of Iron group.

Iron is used in the large amount in the quantities than any other metal, and steel making is of immense importance throughout the world. Iron is also the most importance transition element in plants and animals.In biological importance is an electron carrier in plants and animals. (cytochrome and ferredoxins., as haemoglobin the oxygen carrier in the blood of mammals as myoglobin for oxygen storage, for iron scavenging and storage (ferritin and transferrin) and in nitrogenase (the enzymes in nitrogen-fixing bacteria ). Iron forms several unusual complexes, including ferrocene.

Nickel.

Nickel is moderately abduent and is produced in large quantity. It is used in large quantity in a wide variety of alloys, both ferrous and non-ferrous. It is predominantly divalent and ionic in simple compounds and exists as Ni(+II) in the most of its complexes. These are commonly square planer or octahedral. Palladium and platinum are both rare and expensive. They are noble and not very reactive. They are both used as catalysts. The most common oxidation states are Pd(+II), and Pt(+II), and Pt(+IV) . These are not ionic.

The introduction of Copper.

The element all have one s electron outside a completed d shell. They show only slight similarities in properties and considerable difference . All these metals have the same crystal structure . They conduct electricity and heat particularly well, and they tend to be noble as unreactive. The only ions which exist in solution a part of complexes are Cu(+II), Ag (+I) and Au(+III). Copper is produced on a large scale and 11 million tonnes were used in 1992. Mostly as the metal and in alloys. Copper is biologically important in various oxidase enzymes as an oxygen carrier in invertebrates and in photosynthesis. There is a great interest in various mixed oxides of copper which act as the superconductor.

Reference:

F.A.Cotton and Wilkinson G. Basic inorganic Chemistry. John,Wiley and Sons (Asia), 2007.

Lee., J.D. Concise Inorganic Chemistry. fifth edition. New Delhi: Oxford University Press., 2008.

Sharma, M.L and P.N Chaudhary. A textbook of B.S.C chemistry. Kathmandu Nepal: Ekta Books Thapathali Kathmandu, 2011.