Periodic Table > Osmium
 

Terminology


Allotropes
Some elements exist in several different structural forms, these are called allotropes.


For more information on Murray Robertson’s image see Uses/Interesting Facts below.

 

Fact Box Terminology


Group
Elements appear in columns or ‘groups’ in the periodic table. Members of a group typically have similar properties and electron configurations in their outer shell.


Period
Elements are laid out into rows or ‘periods’ so that similar chemical behaviour is observed in columns.


Block
Elements are organised into blocks by the orbital type in which the outer electrons are found. These blocks are named for the characteristic spectra they produce: sharp, principal, diffuse, and fundamental.


Atomic Number
The number of protons in the nucleus.


Atomic Radius/non -bonded (Å)
based on Van der Waals forces (where several isotopes exist, a value is presented for the most prevalent isotope). These values were calculated using a multitude of methods including crystallographic data, gas kinetic collision cross sections, critical densities, liquid state properties, for more details please refer to the CRC Handbook of Chemistry and Physics.


Electron Configuration
The arrangements of electrons above the last (closed shell) noble gas.


Isotopes
Elements are defined by the number of protons in its centre (nucleus), whilst the number of neutrons present can vary. The variations in the number of neutrons will create elements of different mass which are known as isotopes.


Melting Point (oC)
The temperature at which the solid-liquid phase change occurs.


Melting Point (K)
The temperature at which the solid-liquid phase change occurs.


Melting Point (oF)
The temperature at which the solid-liquid phase change occurs.


Boiling Point (oC)
The temperature at which the liquid-gas phase change occurs.


Boiling Point (K)
The temperature at which the liquid-gas phase change occurs.


Boiling Point (oF)
The temperature at which the liquid-gas phase change occurs.


Sublimation
Elements that do not possess a liquid phase at atmospheric pressure (1 atm) are described as going through a sublimation process.


Density (kgm-3)
Density is the weight of a substance that would fill 1 m3 (at 298 K unless otherwise stated).


Relative Atomic Mass
The mass of an atom relative to that of Carbon-12. This is approximately the sum of the number of protons and neutrons in the nucleus. Where more than one isotope exists the value given is the abundance weighted average.


Key Isotopes (% abundance)
An element must by definition have a fixed number of protons in its nucleus, and as such has a fixed atomic number, however variants of an element can exist with differing numbers of neutrons, and hence a different atomic masses (e.g. 12C has 6 protons and 6 neutrons and 13C has 6 protons and 7 neutrons).


CAS number
The Chemical Abstracts Service registry number is a unique identifier of a particular chemical, designed to prevent confusion arising from different languages and naming systems (where several isotopes exist, a value is presented for the most prevalent isotope).

Fact Box

 
Group Melting point 3033 oC, 5491.4 oF, 3306.15 K 
Period Boiling point 5008 oC, 9046.4 oF, 5281.15 K 
Block Density (kg m-3) 22580 
Atomic number 76  Relative atomic mass 190.23  
State at room temperature Solid  Key isotopes 192Os 
Electron configuration [Xe] 4f145d66s2  CAS number 7440-04-2 
ChemSpider ID 22379 ChemSpider is a free chemical structure database
 

Interesting Facts terminology


Image Explanation

Murray Robertson is the artist behind the images which make up Visual Elements. This is where the artist explains his interpretation of the element and the science behind the picture.


Natural Abundance

Where this element is most commonly found in nature.


Biological Roles

The elements role within the body of humans, animals and plants. Also functionality in medical advancements both today and years ago.


Appearance

The description of the element in its natural form.

Uses / Interesting Facts

 
Image explanation
Imagery suggesting the use of the element in making high quality pen nibs.
Appearance
A shiny silver metal that resists corrosion, and is the densest of all the elements and twice as dense as lead. It is as rare as gold and, like gold, can be found as the free metal. It is little used except in a few alloys and in industry as a catalyst.
Uses
Osmium is almost entirely used to produce very hard alloys for fountain pen tips, instrument pivots, needles and electrical contacts.
Biological role
Osmium has no known biological role, but is very toxic, and can cause lung, skin and eye damage.
Natural abundance
Osmium occurs in the uncombined state and in the mineral osmiridium, but commercial recovery is from the wastes of nickel refining.
 
Atomic Data Terminology

Atomic radius/non -bonded (Å)
Based on Van der Waals forces (where several isotopes exist, a value is presented for the most prevalent isotope). These values were calculated using a multitude of methods including crystallographic data, gas kinetic collision cross sections, critical densities, liquid state properties,for more details please refer to the CRC Handbook of Chemistry and Physics.


Electron affinity (kJ mol-1)
The energy released when an additional electron is attached to the neutral atom and a negative ion is formed (where several isotopes exist, a value is presented for the most prevalent isotope). *


Electronegativity (Pauling scale)
The degree to which an atom attracts electrons towards itself, expressed on a relative scale as a function bond dissociation energies, Ed in eV. χA - χB =(eV)-1/2sqrt(Ed(AB)-[Ed(AA)+Ed(BB)]/2), with χH set as 2.2 (where several isotopes exist, a value is presented for the most prevalent isotope).


1st Ionisation energy (kJ mol-1)
The minimum energy required to remove an electron from a neutral atom in its ground state (where several isotopes exist, a value is presented for the most prevalent isotope).


Covalent radius (Å)
The size of the atom within a covalent bond, given for typical oxidation number and coordination (where several isotopes exist, a value is presented for the most prevalent isotope). ***

Atomic Data

 
Atomic radius, non-bonded (Å) 2.160 Covalent radius (Å) 1.36
Electron affinity (kJ mol-1) 106.096 Electronegativity
(Pauling scale)
2.200
Ionisation energies
(kJ mol-1)
 
1st
814.162
2nd
-
3rd
-
4th
-
5th
-
6th
-
7th
-
8th
-
 

Mining/Sourcing Information

Data for this section of the data page has been provided by the British Geological Survey. To review the full report please click here or please look at their website here.


Key for numbers generated


Governance indicators

1 (low) = 0 to 2

2 (medium-low) = 3 to 4

3 (medium) = 5 to 6

4 (medium-high) = 7 to 8

5 (high) = 9


Reserve base distribution

1 (low) = 0 to 30 %

2 (medium-low) = 30 to 45 %

3 (medium) = 45 to 60 %

4 (medium-high) = 60 to 75 %

5 (high) = 75 %

(Where data are unavailable an arbitrary score of 2 was allocated. For example, Be, As, Na, S, In, Cl, Ca and Ge are allocated a score of 2 since reserve base information is unavailable. Reserve base data are also unavailable for coal; however, reserve data for 2008 are available from the Energy Information Administration (EIA).)


Production Concentration

1 (low) = 0 to 30 %

2 (medium-low) = 30 to 45 %

3 (medium) = 45 to 60 %

4 (medium-high) = 60 to 75 %

5 (high) = 75 %


Crustal Abundance

1 (low) = 100 to 1000 ppm

2 (medium-low) =10 to 100 ppm

3 (medium) = 1 to 10 ppm

4 (medium-high) = 0.1 to 1 ppm

5 (high) = 0.1 ppm

(Where data are unavailable an arbitrary score of 2 was allocated. For example, He is allocated a score of 2 since crustal abundance data is unavailable.)


Explanations for terminology


Crustal Abundance (ppm)

The abundance of an element in the Earth's crust in parts-per-million (ppm) i.e. The number of atoms of this element per 1 million atoms of crust.


Sourced

The country with the largest reserve base.


Reserve Base Distribution

This is a measure of the spread of future supplies, recording the percentage of a known resource likely to be available in the intermediate future (reserve base) located in the top three countries.


Production Concentrations

This reports the percentage of an element produced in the top three countries. The higher the value, the larger risk there is to supply.


Total Governance Factor

The World Bank produces a global percentile rank of political stability. The scoring system is given below, and the values for all three production countries were summed.


Relative Supply Risk Index

The Crustal Abundance, Reserve Base Distribution, Production Concentration and Governance Factor scores are summed and then divided by 2, to provide an overall Relative Supply Risk Index.

Supply Risk

 
Scarcity factor 8.5
Country with largest reserve base South Africa
Crustal abundance (ppm) 3.7E-05
Leading producer South Africa
Reserve base distribution (%) 87.50
Production concentration (%) 58.80
Total governance factor(production) 7
Top 3 countries (mined)
  • 1) South Africa
  • 2) Russia
  • 3) USA
Top 3 countries (production)
  • 1) South Africa
  • 2) Russia
  • 3) USA
 

Oxidation states/ Isotopes


Key for Isotopes


Half Life
  y years
  d days
  h hours
  m minutes
  s seconds
Mode of decay
  α alpha particle emission
  β negative beta (electron) emission
  β+ positron emission
  EC orbital electron capture
  sf spontaneous fission
  ββ double beta emission
  ECEC double orbital electron capture

Terminology


Common Oxidation states
The oxidation state of an atom is a measure of the degree of oxidation of an atom. It is defined as being the charge that an atom would have if all bonds were ionic. Free atoms have an oxidation state of 0, and the sum of oxidation numbers within a substance must equal the overall charge.


Important Oxidation states
The most common oxidation states of an element in its compounds.


Isotopes
Elements are defined by the number of protons in its centre (nucleus), whilst the number of neutrons present can vary. The variations in the number of neutrons will create elements of different mass which are known as isotopes.

Oxidation States / Isotopes

 
Common oxidation states 8, 6, 4, 3, 2, 0, -2
Isotopes Isotope Atomic mass Natural abundance (%) Half life Mode of decay
  184Os 183.952 0.02
  186Os 185.954 1.59 2 x 1015 α 
  187Os 186.956 1.96
  188Os 187.956 13.24
  189Os 188.958 16.15
  190Os 189.958 26.26
  192Os 191.961 40.78
 

Pressure and Temperature - Advanced Terminology


Molar Heat Capacity (J mol-1 K-1)

Molar heat capacity is the energy required to heat a mole of a substance by 1 K.


Young's modulus (GPa)

Young's modulus is a measure of the stiffness of a substance, that is, it provides a measure of how difficult it is to extend a material, with a value given by the ratio of tensile strength to tensile strain.


Shear modulus (GPa)

The shear modulus of a material is a measure of how difficult it is to deform a material, and is given by the ratio of the shear stress to the shear strain.


Bulk modulus (GPa)

The bulk modulus is a measure of how difficult to compress a substance. Given by the ratio of the pressure on a body to the fractional decrease in volume.


Vapour Pressure (Pa)

Vapour pressure is the measure of the propensity of a substance to evaporate. It is defined as the equilibrium pressure exerted by the gas produced above a substance in a closed system.

Pressure / Temperature - Advanced

 
Molar heat capacity
(J mol-1 K-1)
24.7 Young's modulus (GPa) Unknown
Shear modulus (GPa) Unknown Bulk modulus (GPa) Unknown
Vapour pressure  
Temperature (K)
400 600 800 1000 1200 1400 1600 1800 2000 2200 2400
Pressure (Pa)
- - - - - - - 1.85
x 10-10
3.46
x 10-8
2.49
x 10-6
8.75
x 10-5
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History

In 1803, Smithson Tennant added platinum to dilute aqua regia, which is a mixture of nitric and hydrochloric acids, and observed that not all the metal went into solution. Earlier experimenters had assumed that the residue was graphite, but he suspected it was something else, and he began to investigate it. By a combination of acid and alkali treatments he eventually separated it into two new metal elements, which he named iridium and osmium, naming the latter on account of the strong odour it gave off. Its name is derived from osme the Greek word for smell. Although it was recognised as a new metal, little use was made of it because it was rare and difficult to work with, although it was extremely hard wearing and for several years it was used for pen nibs and gramophone needles.

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Podcasts

Listen to Osmium Podcast
Transcript :

Chemistry in Its Element - Osmium


  (Promo)

You're listening to Chemistry in its element brought to you by Chemistry World, the magazine of the Royal Society of Chemistry 

(End promo)

 

Chris Smith

 

Hello this week the illuminating story of the chemical that christened a light bulb company and helps us to find fingerprints but in the wrong hands can stink to high heaven.   To tell the story of the densest element we know here's science broadcaster Quentin Cooper.    

 

Quentin Cooper

Given the whole periodic table to choose from, how to pick a particular element to talk about rather than any other?     They've all got their charms and quirks - well, except maybe bismuth.I've never had much time for bismuth - but the deal was I had to single out one.   And then it came to me.   A real light-bulb moment.    Osmium.   Under-appreciated under-exploited osmium -   if any element needs a change of PR this is the one.    It's brittle, prone to ponginess and arguably the dunce of the periodic table.   Even the man who discovered osmium treated it rather sniffily.     Perhaps in part that's because Smithson Tennant, an English chemist, was also the first to establish that diamond is a form of carbon.so this was never going to match up to that glittering career highlight.   What also didn't help was that his discovery of osmium around 1803 came as part of a job lot - he isolated another element, alongside it: also a metal it was hard and yellowy-white and some of its compounds had a kind of rainbow sheen when they caught the light so he gave it a nice shiny name - iridium as in iridescent.    No such luck for the bluish-silver substance he found at the same time : it reeked - or at least some of its compounds did.   Tennant described the "pungent and penetrating smell"  as one of the new element's "most distinguishing characters".    So he called it osmium - osme being the Greek for odour.    Not very nice.but at least apposite: as a powder even at room temperature it gives off osmium tetroxide, which is so corrosively pungent it can damge the eyes, lungs and skin..although strangely that doesn't prevent it sometimes being used - with extreme care - to help detect fingerprints.. 

So osmium is not just an element, it's a smellement, and it's also way beyond lead and gold and platinum as probably the most immensely dense of the whole bunch.     I say probably because it depends how you measure it - and while some rate it as densest others argue it's just pipped by the very thing it was discovered with, iridium.       Down the decades as tests have been refined, the right to wear the dense-is cap has repeatedly shifted between the two.. making the only safe option to declare them joint-winners of the prestigious title of densest element in the periodic table.     Given the two share both discovery and a date with density it's perhaps no surprise to find they also rub along in nature and occur as an alloy, wittily known as osmiridium - something you'll find in upmarket fountain pen nibs and odd bits of surgical equipment.      Osmium itself also plays a part in some catalysts, and is used for staining specimens in microscopy.   

None of these is what you might call a bulk application - which may account for why it's estimated that the current annual amount of osmium now produced right around the world weighs less than a large tiger.    Or about 100 kilograms if you prefer conventional units.    Time was, though, when osmium was considerably more sought after.    Not because of its density or smelly compounds, but because of its high melting point.    Very high - over 3 thousand degrees C.      After Thomas Edison produced the first commercial electric light in 1879, the race was on to improve on his design - for starters there was the filament - the bit that glows to produce the light but, crucially, doesn't melt.     There had to be something better than Edison's use of bamboo - I mean, bamboo, really.what was he thinking?    Lots of possibilities were explored, but - largely thanks to the work of the Austrian chemist Carl Auer Von Welsbach - the top two elements-as-filaments ended up being osmium and tungsten.which has an even higher melting point.     These days it's tungsten that's the clear favourite, but in 1906 when a name was needed for a new German company making these improved lights, they simply went with a verbal alloy of the two.    Os from Osmium and ram from Wolfram - the German name for Tungsten.hence Osram - now one of the largest lighting manufacturers in the world.and hence my bright light-bulb moment when it came to picking osmium.       

Chris Smith

 

Quentin Cooper who was turning the spotlight for us this week onto Osmium.   Thanks Quentin.   Next time we're meeting the metal that can sooth this burning issue. 

Andrea Sella

 

A few weeks ago I had a stupid accident in the lab; I wont go into the details; I am not terribly proud about what happened. But the result is I suffered from some superficial burns on my face and neck. I was seen to by a specialist nurse who nodded at me and then handed me tub of ointment. 'Its flammacerium', she said, 'apply it twice a day'. 'Flama what', I replied, 'cerium', she said. I was delighted. 'Cerium, it can not be serious, it's my favorite element'.   

Chris Smith

And that's Andrea Sella who will be introducing the chemical that can quite literally get right under your skin but at the same time clean up car emissions and also polish the mirrors of telescopes.   That's the science of Cerium in next week's Chemistry in it's Element, I hope you can join us.    I'm Chris Smith, thank you for listening, see you next time.   

(Promo)

 

Chemistry in its element is brought to you by the Royal Society of Chemistry and produced by thenakedscientists dot com. There's more information and other episodes of Chemistry in its element on our website at chemistryworld dot org forward slash elements. 

 

(End promo)

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Resources

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References

 
Images:  Visual Elements © Murray Robertson 2011
Mining and Sourcing data:  British Geological Survey – natural environment research council.
Text:  John Emsley Nature’s Building Blocks: An A-Z Guide to the Elements, Oxford University Press, 2nd Edition, 2011.
Additional information for platinum, gold, neodymium and dysprosium obtained from Material Value Consultancy Ltd www.matvalue.com
Data: CRC Handbook of Chemistry and Physics, CRC Press, 92nd Edition, 2011.
G. W. C. Kaye and T. H. Laby Tables of Physical and Chemical Constants, Longman, 16th Edition, 1995.
Members of the RSC can access these books through our library.