Osmium


 * Osmium** is a [|chemical element] with the symbol **Os** and [|atomic number] 76. It is a hard, brittle, blue-gray or blue-black [|transition metal] in the [|platinum family] and is the densest natural element, with a [|density] of 22.59 [|g/cm3] (slightly greater than that of [|iridium] and twice that of [|lead]). It is found in nature as an alloy, mostly in platinum ores; its [|alloys] with [|platinum], [|iridium], and other platinum group metals are employed in [|fountain pen] tips, electrical contacts, and other applications where extreme durability and hardness are needed.

Harmful effects: Powdered osmium in air forms the pungent, highly toxic osmium tetr** oxide (OsO4) which can cause lung, skin and eye damage. ** Characteristics: Osmium is a rare, lustrous, very hard, brittle, bluish-white metal. It is the densest of all the elements. (Although osmium's density is very similar to iridiums, osmium's is slightly higher - both measured and calculated. Calculated: Osmium 22.587 ± 0.009 g/cm3 & Iridium: 22.562 ± 0.009 g/cm3 at 20 OC.) Osmium has the highest melting point and the lowest vapor pressure of the platinum group (ruthenium, rhodium, palladium, iridium, and platinum).

Uses of Osmium
Osmium is principally used alloyed with other metals in the platinum group to produce very hard alloys. An alloy of 90% platinum and 10% osmium is used in surgical implants such as pacemakers and replacement heart valves. Osmium tetroxide is used in microscopy as a stain for fatty tissue and in fingerprint detection.
 * almost entirely used to produce very hard alloys with other metals of the platinum group, for fountain pen tips, instrument pivots, and electrical contacts
 * OsO4 is used to detect fingerprints and to stain fatty tissue for microscope slides
 * platinum/osmium 90/10 alloy is used in implants such as pacemakers and replacement valves

Osmium and iridium were discovered at the same time by the British chemist Smithson Tennant in 1803. Osmium and iridium were identified in the black residue remaining after dissolving platinum ore with aqua regia, a mixture of 25% nitric acid (HNO3) and 75% hydrochloric acid (HCl). Today, osmium is primarily recovered during the processing of platinum and nickel ores. Metallic osmium is hard, brittle and very difficult to make. Powdered osmium is easier to make but emits osmium tetroxide (OsO4) when it is exposed to the air. Unfortunately, osmium tetroxide smells bad and is very poisonous. Because of these problems, osmium is primarily used to make very hard alloys. Osmium alloys can be found in ball point pen tips, fountain pen tips, record player needles, electrical contacts and other devices where frictional wear must be minimized.
 * Atomic Number:** 76
 * Atomic Weight:** 190.23
 * Melting Point:** 3306 K (3033°C or 5491°F)
 * Boiling Point:** 5285 K (5012°C or 9054°F)
 * Density:** 22.57 grams per cubic centimeter
 * Phase at Room Temperature:** Solid
 * Element Classification:** Metal
 * Period Number:** 6 **Group Number:** 8 **Group Name:** none
 * What's in a name?** From the Greek word for a smell, **osme**.
 * Say what?** Osmium is pronounced as **OZ-mee-em**.
 * History and Uses:**
 * Estimated Crustal Abundance:** 1.5×10-3 milligrams per kilogram
 * Estimated Oceanic Abundance:** No Data Available
 * Number of Stable Isotopes:** 5 (View all isotope data)
 * Ionization Energy:** 8.7 eV
 * Oxidation States:** +4, +3

Discovery of Osmium
Osmium was discovered in 1803 by Smithson Tennant in the residue left when crude platinum was dissolved by aqua regia (a mixture of hydrochloric acid and nitric acid). Smithson Tennant also discovered [|iridium] at the same time. Osmium's name comes from the Greek word 'osme' meaning a smell associated with toxic osmium tetroxide (OsO4), released by the powdered metal in air.

Isotopes of Osmium
Osmium has 7 naturally occurring isotopes; 6 are stable. Many of these isotopes can live for extremely long periods of time; trillions of years. Each one has specific characteristics that help with the restoration of different particles.


 * Symbol:** Os **Atomic Number:** 76 **Atomic Mass:** 190.23 amu **Melting Point:** 3045.0 °C (3318.15 K, 5513.0 °F) **Boiling Point:** 5027.0 °C (5300.15 K, 9080.6 °F) **Number of Protons/Electrons:** 76 **Number of Neutrons:** 114 **Classification:** Transition Metal **Crystal Structure:** Hexagonal **Density @ 293 K:** 22.4 g/cm3 **Color:** silvery

Atomic Structure

 * [[image:http://www.chemicalelements.com/bohr/b0076.gif width="354" height="353"]] ||  || **Number of Energy Levels:** 6
 * First Energy Level:** **Second Energy Level:** **Third Energy Level:** **Fourth Energy Level:** **Fifth Energy Level:** **Sixth Energy Level:** ||

Isotopes

 * ** Isotope ** || ** Half Life ** ||
 * Os-184 || Stable ||
 * Os-185 || 93.6 days ||
 * Os-186 || 2.0E15 years ||
 * Os-187 || Stable ||
 * Os-188 || Stable ||
 * Os-189 || Stable ||
 * Os-190 || Stable ||
 * Os-190m || 9.9 minutes ||
 * Os-191 || 15.4 days ||
 * Os-191m || 13.1 hours ||
 * Os-192 || Stable ||
 * Os-193 || 30.5 hours ||
 * Os-194 || 6.0 years ||

Facts

 * Date of Discovery:** 1803 **Discoverer:** Smithson Tenant **Name Origin:** From the Greek word //osmë// (odor) **Uses:** tip gold pen points, instrument pivots, electrical light filaments **Obtained From:** ores that contain platinum

76 Os  Osmium 190.23 **What's in a name?** From the Greek word for a smell, **osme**. **Say what?** Osmium is pronounced as **OZ-mee-em**.
 * Density:** 22.57 grams per cubic centimeter
 * Phase at Room Temperature:** Solid
 * Element Classification:** Metal
 * Period Number:** 6 **Group Number:** 8 **Group Name:** none

**Estimated Crustal Abundance:** 1.5×10 -3 milligrams per kilogram **Estimated Oceanic Abundance:** No Data Available **Number of Stable Isotopes:** 5 ( [|View all isotope data] ) **Ionization Energy:** 8.7 eV **Oxidation States:** +4, +3
 * ** [|Electron Shell Configuration] :** ||  ||   || 1s 2 ||   ||   ||   ||   ||   ||   ||   ||
 * 2s 2 ||  || 2p 6 ||   ||   ||   ||   ||   ||
 * 3s 2 ||  || 3p 6 ||   || 3d 10 ||   ||   ||   ||
 * 4s 2 ||  || 4p 6 ||   || 4d 10 ||   || 4f 14 ||   ||
 * 5s 2 ||  || 5p 6 ||   || 5d 6 ||   ||   ||   ||
 * < 6s 2 ||<  ||   ||

Precautions
Finely divided metallic osmium is [|pyrophoric].[|[48]] Osmium reacts with oxygen at room temperature forming volatile osmium tetroxide. Some osmium compounds are also converted to the tetroxide if oxygen is present.[|[48]] This makes osmium tetroxide the main source of contact with the environment. [|Osmium tetroxide] is highly volatile and penetrates skin readily, and is very [|toxic] by inhalation, ingestion, and skin contact.[|[61]] Airborne low concentrations of osmium tetroxide vapor can cause [|lung] congestion and [|skin] or [|eye] damage, and should therefore be used in a fume hood.[|[17]] Osmium tetroxide is rapidly reduced to relatively inert compounds by polyunsaturated vegetable oils, such as [|corn oil].[|[62]]

Price
Osmium is usually sold as a 99% pure powder. Like other precious metals, it is measured by [|troy weight] and by [|grams]. Its price in 2010 was about $400 per Troy ounce (or about $13 per gram), depending on the quantity and its supplier.