Osmium is an extremely hard, brittle, bluish white or gray transition metal in the platinum group metals. It is the densest natural element, being about 0.03 g/cm3 denser than iridium (the second densest natural element) and about twice as dense as lead. Among the platinum family members, osmium has the highest melting point and the lowest vapor pressure.

This precious metal is nearly impossible to fabricate. When alloyed with some of the other metals in the platinum group, such as iridium or platinum, osmium is used in certain applications where extreme hardness and durability are required. A couple examples of these are for electrical contacts and for tips of high quality fountain pens.

Some of the properties osmium possesses are outlined below.

General:

• Chemical Symbol: Os

• Atomic Number: 76

• Category (as an element): Transition Metal

• Group/ Period/ Block (in the Periodic Table): 8/ 6/ d

• Atomic Weight: 190.23 g.mol-1

• Electron Configuration: [Xe] 4f14 5d6 6s2

Physical:

• Density (near room temperature): 22.59 g.cm-3

• Liquid Density (at melting point): 20 g.cm-3

• Melting Point: 3033°C, 5491°F, 3306°K

• Boiling Point: 5012°C, 9054°F, 5285°K

• Heat of Fusion: 57.85 kJ.mol-1

• Heat of Vaporization: 738 kJ.mol-1

Atomic:

• Oxidation States: 8, 7, 6, 5, 4, 3, 2, 1, 0, -1, -2

• Electronegativity: 2.2 (Pauling scale)

• Atomic Radius: 135 picometre

• Covalent Radius: 144±4 picometre

• Ionization Energies: 840 kJ.mol-1 (first), 1600 kJ.mol-1 (second)

The name "osmium" was derived from the Greek word "osme", which means "smell". It was discovered by the English chemists William Hyde Wollaston and Smithson Tennant in London, England in 1803. Wollaston's and Tennant's discovery of the element involved the discovery as well of the other elements in the platinum group.

With an average mass fraction of 0.05 parts-per notation in the continental crust, osmium is known to be one of the least abundant elements in the Earth's crust. It is found in nature in natural alloys or as a pure element. Similar to the other precious metals in the platinum group, osmium can be found in alloys with copper or nickel.

The extreme toxicity and volatility of osmium's oxide makes it nearly impossible for this element to be used in its pure state. For this reason, it is often necessary to alloy osmium with other elements for use in high-wear applications. For example, osmiridium (a natural alloy of osmium and iridium) is alloyed with the other metals in the platinum group and used in instrument pivots and phonograph needles (apart from electrical contacts and fountain pen tips as mentioned earlier). In another example, osmium tetroxide is used to detect fingerprints and to stain fatty tissue for optical and electron microscopy.

Osmium occurs in the platinum-bearing river sands in North America, South America, and in the Ural Mountains in Russia. The latter, in fact, is known to be the site of the second largest alluvial deposit, which today is still mined. The approximate price of commercial osmium (99 percent pure osmium powder) is 100 U.S. dollars per gram.

 

Palladium is a rare precious metal characterized by its lustrous silvery-white appearance. It was discovered by the English chemist William Hyde Wollaston in London, England in 1803, along with his discovery (together with Smithson Tennant, another English chemist) of the other metals in the platinum group. The name "palladium" was coined by Wollaston from the asteroid named "Pallas".

Of the different precious metals in the platinum group (which includes iridium, platinum, osmium, rhodium, and ruthenium), palladium is known to be the least dense. It likewise has the lowest melting point.

Palladium is utilized in many applications because of its unique properties, some of which are provided below.

General:

• Chemical Symbol: Pd

• Atomic Number: 46

• Category (as an element): Transition Metal

• Group/ Period/ Block (in the Periodic Table): 10/ 5/ d

• Atomic Weight: 106.42 g.mol-1

• Electron Configuration: [Kr] 4d10

Physical:

• Density (near room temperature): 12.023 g.cm-3

• Liquid Density (at melting point): 10.38 g.cm-3

• Melting Point: 1554.9°C, 2830.82°F, 1828.05°K

• Boiling Point: 2963°C, 5365°F, 3236°K

• Heat of Fusion: 16.74 kJ.mol-1

• Heat of Vaporization: 362 kJ.mol-1

Atomic:

• Oxidation States: 0, +1, +2, +4, +6

• Electronegativity: 2.2 (Pauling scale)

• Atomic Radius: 137 picometre

• Covalent Radius: 139±6 picometre

• Van der Waals Radius: 163 picometre

• Ionization Energies: 804.4 kJ.mol-1 (first), 1870 kJ.mol-1 (second), 3177 kJ.mol-1 (third)

Palladium is used in the following:

1. Catalytic converters;

2. Jewelry and watch making;

3. Dentistry and surgical instruments;

4. Aircraft spark plugs;

5. Electrical contacts;

6. Connector platings;

7. Manuscript illumination.

Since the late 1930s, palladium has been utilized as a precious metal in jewelry. Because of its naturally white properties, palladium has been used as an alternative to white gold. Along with silver and nickel, palladium is popularly used in making white gold alloys.

According to the British Geological Survey (BGS), the top four palladium-producing countries in the world are Russia, South Africa, Canada, and the United States (in this order). Russia produces at least half of the total amount of palladium produced in the world.

Commercially, palladium is produced from copper-nickel deposits in Siberia, South Africa, and in Ontario in Canada. The precious metal is also found - alloyed with the other metals in the platinum group as well as with gold - in Ethiopia, Australia, North and South America, and in the Ural Mountains in Russia.

The Norilsk Nickel Mining and Metallurgical Company in northern Russia is the largest single producer of palladium in the world. Significant amounts of mineable palladium are also found in two other places: the Lac des Îles igneous complex in northwestern Ontario, Canada and the Stillwater igneous complex in the state of Montana in the United States.

Such is the rarity and preciousness of palladium that many metric tons of ore have to be processed to obtain just a troy ounce of the precious metal. The ISO currency codes of palladium, as a commodity, are XPD and 964. Its price is approximately 150 U.S. dollars per troy ounce.