What is Osmium

Osmium (pronounced as OZ-mee-em) belongs to the family of transition metals and denoted by the chemical symbol Os. It has thirty-four isotopes out of which seven occur naturally with osmium-92 having an abundance of 40.78% in the earth’s crust ^{[1, 3]}. It is also available in the form of powder, bars, balls, and coins for several commercial purposes.

Where is Osmium Found

The element is found in iridomine and platinum-bearing sands of America and Urals. It is also obtained as a by-product from nickel ores ^{[1, 4]}.

History

Origin of its Name: Its name is derived from the Greek word ‘osme’ which means ‘smell’.

When and Where was it Discovered: In 1803, the English chemist Smithson Tennant first synthesized osmium.

How was Osmium Discovered

In 1803, when Tennant added platinum to a mixture of nitric and hydrochloric acids called aqua regia, he noticed that a major portion of the metal failed to dissolve in the solution. Although many researchers assumed the residue contained graphite earlier, he conducted a further analysis to find out. After a series of treatments with acids and alkalis, he was successful in isolating two different elements, and named them iridium and osmium, respectively ^[1].

Position of the Element on the Periodic Table ^[1]

Group	8
Period	6
Block	d

Properties and Characteristics of Osmium ^{[1, 2, 3]}

General Properties
Relative atomic mass/mass number/molar mass	190.23
Atomic mass/weight	190.23 atomic mass units [8]
Physical Properties
Color/appearance	Bluish-white
Luster	Metallic
Odor	Unknown
Malleability	Yes
Ductility	Yes
Melting point/freezing point	3033°C (5491°F)
Boiling point	5088°C (9046°F)
Density	22.5872 g/cm3
State at normal room temperature (solid/liquid/gas)	Solid
Hardness	7 Mohs
Electrical conductivity	Unknown
Magnetic Properties
Magnetic ordering	Paramagnetic
Magnetic susceptibility	+9.9·10−6 cm3/mol at 298 K
Chemical Properties
Flammability		Yes
Oxidation number		Unknown
Oxidation state/Oxidation number		−2, (−1), +1, +2, +3, +4, +5, +6, +7, +8

Atomic Data of Osmium ^{[1, 2, 3]}

What is Osmium Used for

• Addition of the metal to alloys increases hardness making them useful in the manufacture of ballpoint and fountain pens, jewelry like rings, electrical contacts, record player needles, instrument pivots, and other devices prone to frequent wear and tear ^{[1, 2]}.
• Alloys containing 10% of osmium and 90% of platinum are used pacemakers and replacement heart valves ^[3].
• It plays the role of an efficient catalyst in several chemical reactions ^[1].

Dangers and Health Hazards of Osmium

The pure metal does not pose any harmful effects unless exposed to air as it undergoes reaction to form osmium tetraoxide, a poisonous and highly reactive compound, causing lung congestion, skin irritation, and eye problems^{[6, 7]}.

Interesting Facts

• It is the densest element, approximately two times denser than lead ^[1].
• Osmium is the most stable among all the elements  ^[5].

Osmium Price

Pure osmium generally costs between $12,000 and $14,000 per kilogram ($300 and $500 per troy ounce). Osmium-187 is a more expensive and useful isotope, costing somewhere between $15,0000 and $25,0000.

References
1. http://www.rsc.org/periodic-table/element/76/osmium
2. https://education.jlab.org/itselemental/ele076.html
3. https://www.chemicool.com/elements/osmium.html
4. https://www.thoughtco.com/osmium-facts-606570
5. http://www.softschools.com/facts/periodic_table/osmium_facts/346/
6. https://www.webelements.com/osmium/biology.html
7. http://nj.gov/health/eoh/rtkweb/documents/fs/1441.pdf
8. http://hobart.k12.in.us/ksms/PeriodicTable/osmium.htm