Periodic Table > Plutonium
 

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 Actinides  Melting point 640 oC, 1184 oF, 913.15 K 
Period Boiling point 3228 oC, 5842.4 oF, 3501.15 K 
Block Density (kg m-3) 19814 
Atomic number 94  Relative atomic mass 244.064  
State at room temperature Solid  Key isotopes 238Pu, 239Pu, 240Pu 
Electron configuration [Rn] 5f67s2  CAS number 7440-07-5 
ChemSpider ID 22382 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
The image is inspired by Robert Oppenheimer’s quote, following the first atomic bomb test in the Nevada desert. ‘We knew the world would not be the same. A few people laughed, a few people cried. Most people were silent. I remembered the line from the Hindu scripture, the Bhagavad-Gita. Vishnu is trying to persuade the Prince that he should do his duty and to impress him takes on his multi-armed form and says, “Now I am become Death, the destroyer of worlds.” I suppose we all thought that, one way or another.’
Appearance
A radioactive, silvery metal.
Uses
Plutonium was used in several of the first atomic bombs, and is still used in nuclear weapons. The complete detonation of a kilogram of plutonium produces an explosion equivalent to over 10,000 tonnes of chemical explosive.

Plutonium is also a key material in the development of nuclear power. It has been used as a source of energy on space missions, such as the Mars Curiosity Rover and the New Horizons spacecraft on its way to Pluto.
Biological role
Plutonium has no known biological role. It is extremely toxic due to its radioactivity.
Natural abundance
The greatest source of plutonium is the irradiation of uranium in nuclear reactors. This produces the isotope plutonium-239, which has a half-life of 24,400 years.

Plutonium metal is made by reducing plutonium tetrafluoride with calcium.
 
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) 2.430 Covalent radius (Å) 1.8
Electron affinity (kJ mol-1) Unknown Electronegativity
(Pauling scale)
1.300
Ionisation energies
(kJ mol-1)
 
1st
581.439
2nd
1080.635
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 Unknown
Country with largest reserve base Unknown
Crustal abundance (ppm) Unknown
Leading producer Unknown
Reserve base distribution (%) Unknown
Production concentration (%) Unknown
Total governance factor(production) Unknown
Top 3 countries (mined)
  • Unknown
Top 3 countries (production)
  • Unknown
 

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 6, 5, 4, 3
Isotopes Isotope Atomic mass Natural abundance (%) Half life Mode of decay
  238Pu 238.05 - 8.87 y  α 
        4.75 x 1010 sf 
  239Pu 239.052 - 2.410 x 104 α 
        8 x 105 sf 
  240Pu 240.054 - 6.56 x 103 α 
        1.14 x 1011 sf 
  241Pu 241.057 - 14.33 y  β- 
        α 
        > 6 x 1016 sf 
  242Pu 242.059 - 3.75 x 105 α 
        6.77 x 1010 sf 
  244Pu 244.064 - 8.12 x 107 α 
        6.6 x 1010 sf 
 

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)
Unknown 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)
- - - 1.03
x 10-8
6.17
x 10-6
5.94
x 10-4
1.82
x 10-2
0.26 2.2 12.6 53.8
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History

Plutonium was first made in December 1940 at Berkeley, California, by Glenn Seaborg, Arthur Wahl, Joseph Kennedy, and Edwin McMillan. They produced it by bombarding uranium-238 with deuterium nuclei (alpha particles). This first produced neptunium-238 with a half-life of two days, and this decayed by beta emission to form element 94 (plutonium). Within a couple of months element 94 had been conclusively identified and its basic chemistry shown to be like that of uranium.


To begin with, the amounts of plutonium produced were invisible to the eye, but by August 1942 there was enough to see and weigh, albeit only 3 millionths of a gram. However, by 1945 the Americans had several kilograms, and enough plutonium to make three atomic bombs, one of which exploded over Nagasaki in August 1945.

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Podcasts

Listen to Plutonium Podcast
Transcript :

Chemistry in Its Element - Plutonium


  (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 on Chemistry in its Element a substance that most people think is man made but in fact often turns up in the centres of stars.   It also packs a huge nuclear punch when it's in the right sort of warhead and also has the power to be a super conductor.   The only problem is its radio active and that means that when it decays it tends to fall apart.   It is of course Plutonium and here to spell it out is Cambridge University's Ian Farnan.

 

Ian Farnan

 

Plutonium's often billed as the 'most toxic substance known to man'. Just the word plutonium instils a dread in people's minds - And it's the early history of plutonium that established its dark side - and it's a reputation that's been hard to shake-off since. 

 

Glenn Seaborg discovered plutonium at Berkeley in 1940, and in the following spring, when it was found that it could sustain a nuclear chain reaction, he secretly wrote to President Roosevelt, to inform him of that this substance had the potential to be a powerful source of nuclear energy. And from that moment the race was on to produce significant amounts to supply a secret project codenamed the Manhattan Engineering District, the goal of which was to produce a nuclear bomb.

 

Anyone familiar with the iconic image of the mushroom cloud understands the tremendous explosive power of a correctly controlled detonation of plutonium.   The energy density is mind-boggling: a sphere of metal 10 cm in diameter and weighing just 8 Kg is enough to produce an explosion at least as big as the one that devastated Nagasaki in 1945.  

 

But apart from military uses like this, plutonium also has one of the richest chemistries of any element. There are six different forms of plutonium, known as allotropes, that all exist at different temperatures and behave differently. 

 

At room temperature, for instance, the plutonium is very brittle, but heated to around 100 Celsius is transforms to a much more malleable metal. Scientists have found that they can mimic this effect by adding a small amount of gallium, which gives the room temperature metal similar properties to its higher-temperature counterpart, and this makes it much easier to work with.

 

Mixing plutonium with other metals can also produce substances with other interesting properties. For instance, adding some cobalt and gallium can produce a material that behaves as a super-conductor at low temperatures. Its electrons link up into a close-knit arrangement called Cooper pairs, which allow electricity to flow freely with no resistance.

 

But unfortunately this arrangement doesn't last very long. Because plutonium-239 self destructs, undergoing radioactive decay by spitting out a highly energetic alpha-particle to produce Uranium-235. 

 

But as the alpha-particle leaves it causes the uranium nucleus to recoil like a gun that's just been fired, and this damages the structure of the material, disrupting the paired electrons and slowly destroying the superconductivity.  

 

So in this sense plutonium is its own worst enemy. Its radioactivity means that it's very difficult to exploit the richness of its chemistry in many compounds, and as its reputation precedes it, plutonium would also have trouble gaining acceptance as a technological material. 

 

But despite its tarnished reputation, some people quite literally have a place in their hearts for plutonium because one of its isotopes, plutonium­-238, generates so much heat when it decays, that it was used as a long-lasting thermoelectric generator in early heart pacemakers. 

 

Nowadays it's been replaced by better batteries, but it's still popular with space scientists who use it to power probes sent to explore distant planets far from the Sun, like Cassini, that was sent to Saturn, and New Horizons, which is on its way to Pluto.

 

Plutonium's in a part of the periodic table called the actinide series alongside its neighbours thorium and protoactinium. Seaborg christened the actinides, rearranging the periodic table in the process, on the basis of the unusual arrangements of their electrons, which give these substances unusual magnetic properties, as well as the ability to have multiple oxidation states. Plutonium, for instance, has five, giving it the ability to form an unusually wide range of compounds that scientists are only just beginning to get to grips with.

 

Some say that plutonium's an evil element created by man, but it's actually a natural element produced by a process known as nucleosynthesis, which takes place in supernova explosions, when dying stars blow themselves to pieces. 

 

There isn't much of it on the earth naturally, because the majority of its isotopes have such short half-lives. And in the 4.6 billion years since our solar system began to form, most of them have decayed away to infinitesimally tiny amounts. What there is mostly comes from reactors and nuclear tests.

 

There are severe hazards associated with plutonium, but as with most dangerous materials, these can be mitigated by careful handling and rigorous safeguards. 

 

But whatever you think about plutonium, its history, however chequered, has revealed some fascinating chemistry. Although the mushroom cloud remains its best-known image.

 

Chris Smith

 

Ian Farnan, unpacking Plutonium.   Next time on Chemistry in its Element the toxic chemical that saves thousands of lives every year.  

 

Peter Wothers

 

In his list of the then known elements, Lavoisier included the term azote meaning the absence of life, but the compound used to explosively fill car air bags with gas is sodium azide, a compound of just Sodium and Nitrogen. When triggered this compound explosively decomposes freeing the Nitrogen gas, which inflates the bags.   Far from

destroying life, this azotic compound has been responsible for saving thousands.

 

 

Chris Smith

 

Peter Wothers talking nitrogen on what promises to be an explosive edition of Chemistry in its Element next week.   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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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.