Periodic Table > Mendelevium
 

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 827 oC, 1520.6 oF, 1100.15 K 
Period Boiling point Unknown 
Block Density (kg m-3) Unknown 
Atomic number 101  Relative atomic mass 258.098  
State at room temperature Solid  Key isotopes 258Md, 260Md 
Electron configuration [Rn] 5f137s2  CAS number 7440-11-1 
ChemSpider ID 22385 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, and based on, a photograph of Dimitri Mendeleev and an early version of the periodic table.
Appearance
A radioactive metal, of which only a few atoms have ever been created.
Uses
Mendelevium is used only for research.
Biological role
Mendelevium has no known biological role.
Natural abundance
Mendelevium does not occur naturally. It is made by bombarding einsteinium with alpha particles (helium ions).
 
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) 2.460 Covalent radius (Å) 1.73
Electron affinity (kJ mol-1) Unknown Electronegativity
(Pauling scale)
Unknown
Ionisation energies
(kJ mol-1)
 
1st
634.873
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 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 3
Isotopes Isotope Atomic mass Natural abundance (%) Half life Mode of decay
  258Md 258.098 - 51.5 d  α 
        sf 
  260Md 260.104 - ~ 27.8 d  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)
- - - - - - - - - - -
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History

Seventeen atoms of mendelevium were made in 1955 by Albert Ghiorso, Bernard Harvey, Gregory Chopin, Stanley Thompson, and Glenn Seaborg. They were produced during an all-night experiment using the cyclotron at Berkeley, California. In this, a sample of einsteinium-253 was bombarded with alpha-particles (helium nuclei) and mendelevium-256 was detected. This had a half-life of around 78 minutes. Further experiments yielded several thousand atoms of mendelevium, and today it is possible to produce millions of them. The longest lived isotope is mendelevium-260 which has a half-life of 28 days.

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Podcasts

Listen to Mendelevium Podcast
Transcript :

Chemistry in its element - mendelevium


(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) 

Meera Senthilingam 

This week's element pays tribute to the creator of the periodic table. Here's Hayley Birch:

Hayley Birch

In 1933, Albert Einstein was visiting a friend at the University of California, Los Angeles, when he was introduced to an aspiring scientist by the name of Glenn Theodore Seaborg. Seaborg was studying chemistry and was only an undergraduate, but Einstein took the time to talk to him and encourage him in his scientific endeavours. 

This meeting seems to have had a profound effect on the young Seaborg, who went on, like Einstein, to become a Nobel Prize winner and wrote in a tribute many years later that he had been much impressed by the great man's modesty and kindness. He also remarked upon Einstein's dedication to peace and was perhaps inspired by him in his own attitude to war. Despite playing a central role in the creation of the atomic bomb by helping to separate plutonium from uranium, he is said to have remained a pacifist and believed that nuclear energy should be used only for good. 

By what appears to have been pure coincidence, it was on the day of Einstein's death - the 18 April 1955 - that the American Physical Society received a paper from Seaborg and his colleagues at the University of California, Berkeley, announcing the discovery of a new radioactive element that was to become known as mendelevium. At its most stable atomic weight of 258, it is considered one of the 'superheavy'-weights of the periodic table. Like most of the heavier elements, it's so large that it has trouble sticking itself together and usually decays after just a couple of hours - which is why Seaborg and his colleagues had to create it synthetically. 

Considering his contribution to the Manhattan project, mendelevium was certainly not Seaborg's most significant achievement. It was not even his first element: he was part of a team based at the Radiation Laboratory that had already announced the discovery of americium and curium, as well as berkelium and californium, named after his own university. Four years previously he had been awarded the Nobel Prize, along with Edwin McMillan, for these very achievements, lumped together under what they called the trans-uranium elements - because they had atomic numbers higher than uranium. 

At atomic number 101, mendelevium was a different type of element: the first of the trans-fermium elements. But to make it, Seaborg employed the same piece of equipment - the particle accelerator that had been used to chemically identify plutonium after it was discovered by Enrico Fermi during the Second World War. The '60-inch Cyclotron', as it was called, was built according to the design of Ernest Lawrence, another of Seaborg's colleagues from the Manhattan project, and had already been in operation for well over a decade. When it was finally decommissioned in 1962, it was hailed as the 'most productive atom-smasher in history'. 

To make their synthetic element, Seaborg's team began with a tiny amount of another element, one which had first shown up in the fallout of a nuclear test carried out by the US in 1952. This other element was later to become einsteinium but it appears in the mendelevium paper as simply '99', accompanied by its isotope number, 253. The team used the cyclotron to smash helium ions into their 'element 99' and produce just a few atoms - 17, to be precise - of mendelevium. Even since its discovery, so little mendelevium has ever been produced that scientists haven't had a chance to find a use for it. 

In the Physical Review paper announcing their discovery, Seaborg and his colleagues paid tribute to yet another great scientist. As they wrote: "We would like to suggest the name mendelevium... in recognition of the pioneering role of the great Russian chemist, Dmitri Mendeleev, who was the first to use the periodic system of the elements to predict the chemical properties of undiscovered elements." 

And perhaps there is no more fitting time in this  series to pay our own tribute to Mendeleev, who is, after all, the man responsible for the Periodic Table on which the Chemistry in its Element podcast is based. Brought up in Russia, Mendeleev was the sort of person who, it seems, was incapable of sticking to one discipline and as well as serving as the director of the Russian institute for weights and measures, had a hand in developing the Russian oil industry. Given all this, it's perhaps less surprising than it ought to be that he conceived of the Periodic Table on the same day that he was supposed to be inspecting a cheese factory. 

And so, in mendelevium, Mendeleev got his element and, eventually, so did Seaborg, whom element 106 is named for. 

 

Meera Senthilingham

 

So, both Mendeleev and Seaborg got their elements in the end. That was science writer Hayley Birch, bringing us the atom-smashing chemistry of mendelevium.

Now, next week, continuing along the lines of smashing atoms, we go one step further and experience elemental warfare.

Simon Cotton

In the days of the Cold War, America and Russia rivalled each other in all sorts of ways. Never mind thermonuclear bombs and intercontinental ballistic missiles to deliver them, they competed in putting men and women into space; who could win the most medals in the Olympic Games; and in making new chemical elements. In the case of element 105, the controversy went on for nearly 30 years and was part of the so-called 'Transfermium Wars', when no blood was spilt but a great deal of ink was.

In the Red corner, the Soviet team at the Joint Institute for Nuclear Research at Dubna, near Moscow, led by Georgy Flerov. In the Blue corner, the American team at the University of California at Berkeley, led by Albert Ghiorso.

Meera Senthilingham

And to find out which side came through with the chemistry (and name) of element 105, Dubnium, join Simon Cotton for next week's chemistry in its element. Until then, I'm Meera Senthilingham and thank you for listening.

(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.