Iridium chemical properties

Platinum metah—includes unreactive transition elements located in groups 8, 9, and 10 of periods 5 and 6. They have similar chemical properties. They are ruthenium, rhodium, palladium, osmium, iridium, and platinum. 

Platinum is the main metal in the platinum group, which consists of metals in both period 5 and period 6. They are ruthenium (Ru), rhodium (Ro), and palladium (Pd) in period 5 and osmium (Os), iridium (Ir), and platinum (Pt) in period 6. All six of these metals share some of the same physical and chemical properties. Also, the other metals in the group are usually found in platinum ore deposits. 

Polyhydroxy compounds are oxidized by such metal ions as vanadium(V), chromium(VI), cerium(IV), iridium(IV), and gold(III), among others. These oxidations were found to be catalyzed by acids.171 173 Vanadium(V) and chromium(VI) are closely related in their chemical properties, but the reduction of V(V) is difficult compared with that of Cr(VI) because of its lower redox potential [V(V)-V(IV) = 1.00 V Cr(VI)-Cr(III) = 1.20 V], However, the redox potential increases at lower pH values, facilitating the oxidation of sugars. 

Chemical Properties.—Iridium is not attacked by fluorine in the cold, but on warming to dull redness, vapours of the fluoride are evolved.7 Also, when employed as anode in the preparation of fluorine,8 it is rapidly attacked. Chlorine at red heat unites with iridium to form the trichloride a mixture of chlorine and carbon monoxide at 240° C. has no action on the metal9 although platinum is attacked by it. 

A study of the chemical properties of iridium and its compounds shows that, whilst closely resembling platinum in many respects, it forms a fitting link between that element and osmium. With an atomic weight intermediate in value between 190-9 (at. wt. of osmium) and 195-2 (at. wt. of platinum), iridium falls into a suitable position in the Periodic Table where these analogies are recognised. 

Occurrouoo and History of Iridium—Preparation—Purilieation -Physical and Chemical Properties—Atomic Weight—Usos—Alloys. 

Iridium is a third-row d-block metal and is the heaviest element in group 9. It is a hard, lustrous, silvery metal, discovered by Tennant in 1803 the name iridium derives from the Latin iris (rainbow). The element occurs as a native platinum alloy and in osmiridium (a native alloy of osmium, 15-40%, and iridium, 50-80%). Selected physical and chemical properties of Ir are given in Table 1. It is considered both as a platinum metal and as a precious metal. At room temperature, Ir is particularly resistant to corrosion. 

In its chemical properties, the oxyfluoride behaves as a derivative of five-positive platinum. Potassium hexafluoroplatinatc(v) (Found F, 32-0. KPtF, requires F, 32-7%) is formed when the oxyfluoride vapour is passed over hot potassium fluoride and when potassium fluoride is mixed with the oxy-fluoridc in iodine pentafluoride solution. Potassium hexafluoroplatinatc(v) has a rhombohedral unit cell with a = 4-97 A, a = 97-5°, and is isomorphous with its ruthenium, osmium, and iridium analogues. Dissolution of the oxyfluoride in chlorine trifluoride and in iodine p>entafluoride yields 1 1 platinum penta-fluoridc-solvent adducts. 

There are characteristic chemical properties of cosmic dust that have been involved in the study of sediment accumulation rates. The platinum group elements, such as iridium and osmium, offer good examples. Attempts to use iridium in this way have had the important result of indicating a giant meteorite impact at the Cretaceous-Tertiary boundary (Alvarez et ai, 1980) but it has not been proven important in determining chronometry. 

Osmium is an element in Group 8 (VIIIB) of the periodic table. The periodic table is a chart showing how chemical elements are related to one another. Osmium is also a member of the platinum family. This family consists of five other elements ruthenium, rhodium, palladium, iridium, and platinum. These elements often occur together in Earth s cmst. They also have similar physical and chemical properties, and they are used in alloys. 

The lanthanide contraction, however, has also effects for the rest of the transition metals in the lower part of the periodic system. The lanthanide contraction is of sufficient magnitude to cause the elements which follow in the third transition series to have sizes very similar to those of the second row of transition elements. Due to this, for instance hafnium (Hf ) has a 4" -ionic radius similar to that of zirconium, leading to similar behavior of these elements. Likewise, the elements Nb and Ta and the elements Mo and W have nearly identical sizes. Ruthenium, rhodium and palladium have similar sizes to osmium iridium and platinum. They also have similar chemical properties and they are difficult to separate. The effect of the lanthanide contraction is noticeable up to platinum (Z = 78), after which it no longer noticeable due to the so-called Inert Pair Effect (Encyclopedia Britannica 2015). The inert pair effect describes the preference of post-transition metals to form ions whose oxidation state is 2 less than the group valence. 

Elements which are similar as regards their chemical properties have atomic weights which are either of nearly the same value (platinum, iridium, osmium), or which increase regularly (potassium, rubidium, caesium). 

Chemical Properties. Iridium is not attacked by acids or alkali even under oxidizing conditions (aqua re-... 

Using only very small quantities of the substances, Seaborg and his collaborators succeeded in obtaining a considerable amount of information about the chemical properties of the transuranium elements. They have found that, whereas uranium is similar to tungsten in its properties, in that it has a pronounced tendency to assume oxidation state +6, the succeeding elements are not similar to rhenium, osmium, iridium, and platinum, but show an increasing tendency to form ionic compounds in which their oxidation number is +3. This behavior is similar to that of the rare-earth metals. 

THE NOBLE METALS, or precious metals, consist of gold, silver, and the platinum group metals (PGM)— platinum, palladium, iridium, rhodium, osmium, and ruthenium. These metals are known for their stability in corrosive environments, physical beauty, and unique physical and chemical properties. They command a premium price because of their low abundance in nature. The noble metals are used in many applications with great success and often with few, if any, substitutable materials. 

---