Periodic Table > Cobalt
 

Terminology


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


For more information on Murray Robertson’s image see Uses and properties 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 1495 oC, 2723 oF, 1768.15 K 
Period Boiling point 2927 oC, 5300.6 oF, 3200.15 K 
Block Density (kg m-3) 8800 
Atomic number 27  Relative atomic mass 58.933  
State at room temperature Solid  Key isotopes 59Co 
Electron configuration [Ar] 3d74s2  CAS number 7440-48-4 
ChemSpider ID 94547 ChemSpider is a free chemical structure database
 

Uses and properties 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 and properties

 
Image explanation

A goblin or “kobold” (often accused of leading German miners astray in their search for Tin) against a backdrop of early Chinese porcelain using the element as a now familiar blue glaze.

Appearance

A lustrous, silvery metal with a blue cast.

Uses

Cobalt metal is used in electroplating because of its attractive appearance, hardness and resistance to oxidation. It is alloyed with iron, nickel and other metals, and used in jet turbines and gas turbine generators where high temperature strength is important. Cobalt salts have been used for centuries to produce brilliant blue colours in porcelain, glass, pottery and enamels. It can be magnetised like iron and so is used to make magnets, as well as in ceramics and paints. Radioactive cobalt-60 is used in the treatment of cancer and, in some countries, to irradiate food to preserve it.

Biological role

Cobalt is an essential trace element, and forms part of the active site of vitamin B12. The amount needed is very small, and the body contains only about 1 milligram. Cobalt salts in small doses have been found to be effective in correcting mineral deficiencies in certain animals. Cobalt in large doses is carcinogenic. Radioactive artificial cobalt-60 is an important gamma-ray source, and is used extensively as a tracer and radiotherapeutic agent.

Natural abundance

Cobalt is found in the minerals cobaltite, smaltite and erythrite. Important ore deposits are found in Zaire, Morocco and Canada. A huge reserve of several transition metals (including cobalt) can be found in strange nodules on the floors of the deepest oceans. The nodules are manganese minerals that take millions of years to form, and there are many tonnes of cobalt present in this form. 

 
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) 2.000 Covalent radius (Å) 1.18
Electron affinity (kJ mol-1) 63.851 Electronegativity
(Pauling scale)
1.880
Ionisation energies
(kJ mol-1)
 
1st
760.400
2nd
1648.354
3rd
3232.256
4th
4949.694
5th
7670.578
6th
9841.496
7th
12436.950
8th
15225.374
 

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 5.5
Country with largest reserve base DRC
Crustal abundance (ppm) 26.6
Leading producer DRC
Reserve base distribution (%) 36.20
Production concentration (%) 62.90
Total governance factor(production) 6
Top 3 countries (mined)
  • 1) DRC
  • 2) Cuba
  • 3) Australia
Top 3 countries (production)
  • 1) DRC
  • 2) Zambia
  • 3) Australia
 

Oxidation states and 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 and isotopes

 
Common oxidation states 3, 2, 0, -1
Isotopes Isotope Atomic mass Natural abundance (%) Half life Mode of decay
  59Co 58.933 100
 

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 and temperature data – advanced

 
Molar heat capacity
(J mol-1 K-1)
24.81 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)
- - - 2.09
x 10-10
1.00
x 10-6
4.19
x 10-4
3.79
x 10-2
1.15 16 - -
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History

The tomb of Pharaoh Tutankhamen, who ruled from 1361-1352 BC, contained a small glass object coloured deep blue with cobalt. Cobalt blue was known even earlier in China and was used for pottery glazes.


In 1730, chemist Georg Brandt of Stockholm became interested in a dark blue ore from some local copper workings and he eventually proved that it contained a hitherto unrecognised metal and he gave it the name by which its ore was cursed by miners in Germany, where it was sometimes mistaken for a silver ore. He published his results in 1739. For many years his claim to have uncovered a new metal was disputed by other chemists who said his new element was really a compound of iron and arsenic, but eventually it was recognised as an element in its own right.

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Podcasts

Listen to Cobalt Podcast
Transcript :

Chemistry in its Element - Cobalt


  (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 - beauty, blue glass, B12 and the best magnets that money can buy.   So why is this week's element named after a goblin?  

 

Sarah Staniland

 

I always find the question 'what's your favourite element' a difficult one. There are several front runners for vastly varying reasons; however, always a top contender has to be cobalt because it excels in several important character traits: Cobalt has amazing beauty and strength, as well as great cooperation. All together a highly useful metal.

 

Before I even thought about the chemistry of colour I developed a love for blue glass, something I still collect to this day. Only after studying the transition metal chemistry did I realise that this beautiful blue colour comes from cobalt. Cobalt chloride in fact.  

 

However, as far as colours go, cobalt has a few more strings to its bow than just this wonderful blue. Cobalt can also colour glass green, while the hydrated form of Cobalt chloride is a beautiful deep rose colour. As you can imagine this colour change due to the presence of water is highly useful, warranting cobalt chloride an ideal moisture indicator.

 

The array of beautiful colours that cobalt produces were never more prevalent to me than when I went to the cobalt mining region called the Copperbelt in Zambia. In this area the huge multicoloured cobalt minerals deposits tower high, with the shores of dams and streams coloured deep rose with silvery blue veins running through. 

 

Cobalt it is not found pure in Nature but found in sulphur minerals and usually associated with other transition metals. As you can probably guess from the name of the region in Zambia - the Copperbelt, cobalt is mined as a secondary product to copper that is dominant in the ore of this region. Because of this cobalt is normally recovered from the waste of the primary metal extraction. 

 

However these mining hotspots are not the only places on the Earth where high concentrations of cobalt can be found. A huge reserve of several transition metals (including cobalt) can be found in strange nodules on the floors of the deepest oceans. The nodules are manganese minerals that take millions of years to form, and there are many tonnes of cobalt present in this form. 

 

So you can see that cobalt is never found alone but always palled up with other transition metals in their ores, mainly copper and nickel. In fact cobalt metal was not isolated and purified until as late as 1735 by the Swedish scientist G. Brandt. 

 

Cobalt can also sometimes be found in mixed arsenic ores, and it is cobalt's association with arsenic that gives it its name. The word cobalt comes from the German "Kobolds" which means goblin or trouble maker. It was so called in this early mining region because it was very difficult to smelt without oxidising and smelting would release the associated arsenic vapours which would lead to pretty troublesome or even deadly processing conditions for the worker. The Kobolds were blamed and the name stuck.

 

With the exception of the mining region, cobalt is not very abundant, with only trace amounts in the Earths crust (about 2500 times less than iron). However, it is a metal that is essential for life in the trace amounts. Cobalt is the metal at the centre of vitamin B12 which helps regulate cell development and therefore DNA and energy production in the body. 

 

Cobalt has been known and used by people for its beautiful colouring and pigment properties as far back as 2500BC. Egyptian cobalt blue paints and Prussian cobalt oxide necklaces have been dated back to this time while cobalt glass has been found in a Greek vase dated at 100 BC. Cobalt was also used to colour glass in the Chinese Tang dynasty from 618 AD. In fact all the way up until the beginning of the 20th century people have only really exploited cobalt for its beautiful colour.

 

However cobalt is not just a pretty face. Cobalt is a lustrous very hard silvery metal belonging to a group called the "transition metals". It is one of only 3 ferromagnetic transition elements along with iron and nickel. As a metal it is very mechanically hard and tough, and it has a very high melting point (hence the smelting problems) and also remains magnetic to the highest temperature of all the magnetic elements. 

 

When cobalt is combined with other metals its strength allow a range of super alloys to be created. In particular, cobalt's very high melting point and mechanical strength at high temperatures has seen its extensive use in what is termed 'superalloys'. These are alloys that retain mechanical strength at high temperatures. Because of its impressive properties cobalt is an important component in wear resistant and corrosive resistant alloys. And cobalt alloys and coatings are seen everywhere from drills to saws, from aircraft turbines to prosthetic bone replacements. 

 

The fact that cobalt is magnetic has also been exploited with the Japanese invention of cobalt magnetic steel where adding cobalt to steel vastly increases the magnetic hardness. Just a few years after that in the 1930s saw the pivotal invention of Alnico magnets, which as the name suggests, are composed of aluminium, nickel and cobalt. 

 

The fact that cobalt retains its magnetism up to high temperatures is also a very favourable trait when the addition of cobalt to a magnetic material can improve its properties at high temperatures.   More recently the creation of rare-earth magnets have given us much stronger, harder, permanent magnets than Alnico magnets. One such magnetic material, samarium cobalt retains its magnetism up to 800°C. Because it is magnetically and mechanically hard up to very high temperatures, it has found uses in high-speed motors and turbo machinery. More recently cobalt has a major use in newer batteries, magnetic particles for recording and storage information in magnetic tapes and hard drives. 

 

So cobalt; giving joy in an array of beautiful colours, but also ultra strong, hard and magnetic. Cobalt is never alone, it is found associated with different metals in their ore and has its best mechanical properties when palled up with others.

 

Chris Smith

 

Emphasising the importance, of course, of teamwork.   That was Sarah Staniland with the story of Cobalt - she's based at the University of Leeds.   Next week it's the turn of the stuff that amongst other things makes Parker pen nibs write so nicely, but if you haven't heard of it before, then you're probably in good company.  

 

Jonathan Steed 

 

Stop the proverbial "man in the street" and ask him what ruthenium is and the chances are he won't be able to tell you. Compared to the "sexier elements" that are household names like carbon and oxygen, ruthenium is, frankly, a bit obscure. In fact even if your man in the street was wearing a lab coat and walking on a street very close to a university chemistry department he might still be a bit ignorant about this mysterious metal. It wasn't always that way, though. 

 

Chris Smith

 

And you can hear how Ruthenium rose to prominence with Jonathan Steed on next week's Chemistry in its Element.   I'm Chris Smith, thank you for listening and goodbye.

 

(Promo)

 

Chemistry in its elementis 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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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.