Glossary


Allotropes
Some elements exist in several different structural forms, called allotropes. Each allotrope has different physical properties.


For more information on the Visual Elements image see the Uses and properties section below.

 

Glossary


Group
A vertical column in the periodic table. Members of a group typically have similar properties and electron configurations in their outer shell.


Period
A horizontal row in the periodic table. The atomic number of each element increases by one, reading from left to right.


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 (s), principal (p), diffuse (d), and fundamental (f).


Atomic number
The number of protons in an atom.


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


Melting point
The temperature at which the solid–liquid phase change occurs.


Boiling point
The temperature at which the liquid–gas phase change occurs.


Sublimation
The transition of a substance directly from the solid to the gas phase without passing through a liquid phase.


Density (g cm−3)
Density is the mass of a substance that would fill 1 cm3 at room temperature.


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.


Isotopes
Atoms of the same element with different numbers of 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.


Fact box

Group Actinides  Melting point 1627°C, 2961°F, 1900 K 
Period Boiling point Unknown 
Block Density (g cm−3) Unknown 
Atomic number 103  Relative atomic mass [262]  
State at 20°C Solid  Key isotopes 262Lr 
Electron configuration [Rn] 5f147s27p1  CAS number 22537-19-5 
ChemSpider ID 28934 ChemSpider is a free chemical structure database
 

Glossary


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.


Appearance

The description of the element in its natural form.


Biological role

The role of the element in humans, animals and plants.


Natural abundance

Where the element is most commonly found in nature, and how it is sourced commercially.

Uses and properties

Image explanation
The element is named after Ernest Lawrence, who invented the cyclotron particle accelerator. This was designed to accelerate sub-atomic particles around a circle until they have enough energy to smash into an atom and create a new atom. This image is based on the abstract particle trails produced in a cyclotron.
Appearance
A radioactive metal of which only a few atoms have ever been created.
Uses
Lawrencium has no uses outside research.
Biological role
Lawrencium has no known biological role.
Natural abundance
Lawrencium does not occur naturally. It is produced by bombarding californium with boron.
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History

This element had a controversial history of discovery. In 1958, the Lawrence Berkeley Laboratory (LBL) bombarded curium with nitrogen and appeared to get element 103, isotope-257. In 1960, they bombarded californium with boron hoping to get isotope-259 but the results were inconclusive. In 1961, they bombarded curium with boron and claimed isotope-257.

In 1965, the Soviet Union’s Joint Institute for Nuclear Research (JINR) successfully bombarded americium with oxygen and got isotope-256. They also checked the LBL’s work, and claimed it was inaccurate. The LBL then said their product must have been isotope-258. The International Unions of Pure and Applied Chemistry awarded discovery to the LBL.
 
Glossary

Atomic radius, non-bonded
Half of the distance between two unbonded atoms of the same element when the electrostatic forces are balanced. These values were determined using several different methods.


Covalent radius
Half of the distance between two atoms within a single covalent bond. Values are given for typical oxidation number and coordination.


Electron affinity
The energy released when an electron is added to the neutral atom and a negative ion is formed.


Electronegativity (Pauling scale)
The tendency of an atom to attract electrons towards itself, expressed on a relative scale.


First ionisation energy
The minimum energy required to remove an electron from a neutral atom in its ground state.

Atomic data

Atomic radius, non-bonded (Å) 2.46 Covalent radius (Å) 1.61
Electron affinity (kJ mol−1) Unknown Electronegativity
(Pauling scale)
Unknown
Ionisation energies
(kJ mol−1)
 
1st
472.8
2nd
-
3rd
-
4th
-
5th
-
6th
-
7th
-
8th
-
 

Glossary


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. Uncombined elements have an oxidation state of 0. The sum of the oxidation states within a compound or ion must equal the overall charge.


Isotopes

Atoms of the same element with different numbers of neutrons.


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

Oxidation states and isotopes

Common oxidation states 3
Isotopes Isotope Atomic mass Natural abundance (%) Half life Mode of decay
  262Lr 262.110 - 3.6 h  EC 
       
 
sf 
 

Glossary

Data for this section been provided by the British Geological Survey.


Relative supply risk

An integrated supply risk index from 1 (very low risk) to 10 (very high risk). This is calculated by combining the scores for crustal abundance, reserve distribution, production concentration, substitutability, recycling rate and political stability scores.


Crustal abundance (ppm)

The number of atoms of the element per 1 million atoms of the Earth’s crust.


Recycling rate

The percentage of a commodity which is recycled. A higher recycling rate may reduce risk to supply.


Substitutability

The availability of suitable substitutes for a given commodity.
High = substitution not possible or very difficult.
Medium = substitution is possible but there may be an economic and/or performance impact
Low = substitution is possible with little or no economic and/or performance impact


Production concentration

The percentage of an element produced in the top producing country. The higher the value, the larger risk there is to supply.


Reserve distribution

The percentage of the world reserves located in the country with the largest reserves. The higher the value, the larger risk there is to supply.


Political stability of top producer

A percentile rank for the political stability of the top producing country, derived from World Bank governance indicators.


Political stability of top reserve holder

A percentile rank for the political stability of the country with the largest reserves, derived from World Bank governance indicators.


 

Glossary


Specific heat capacity (J kg−1 K−1)

Specific heat capacity is the amount of energy needed to change the temperature of a kilogram of a substance by 1 K.


Young's modulus

A measure of the stiffness of a substance. 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

A measure of how difficult it is to deform a material. It is given by the ratio of the shear stress to the shear strain.


Bulk modulus

A measure of how difficult it is to compress a substance. It is given by the ratio of the pressure on a body to the fractional decrease in volume.


Vapour pressure

A 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

Specific heat capacity
(J kg−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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Podcasts

Listen to Lawrencium Podcast
Transcript :

Chemistry in its element: lawrencium


(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 it's our final chemical element, and it doesn't seem to know its place. Eric Scerri.

Eric Scerri

Element 103 in the periodic table is called lawrencium. It was first synthesised in 1961 at what was then called the Lawrence Radiation Laboratory, situated close to San Francisco. The synthesis was carried out by a team of scientists led by Albert Ghiorso. The element was named after Ernest Lawrence, the inventor of the cyclotron particle accelerator that was used in the synthesis of many transuranium elements.

Starting in 1969 the chemical properties of lawrencium began to be explored. In the gas phase the element forms a trichloride. Studies of its aqueous phase also show that it displays trivalency. You might think that these experiments and others like it would have settled the precise position of lawrencium in the periodic table, but this has not been the case.

In recent years there has been an ongoing debate concerning the placement of lawrencium, and also element 71 or lutetium. Some periodic tables place lutetium and lawrencium one above the other, as the last of the lanthanides and the actinides respectively.

However, on a significant number of more recent periodic tables you will find lutetium and lawrencium classified as transition metals and placed directly underneath scandium and yttrium in group 3 of the periodic table. How can such disagreement still persist at the end of the first decade of the 21st century?

The answer is that electronic configurations of atoms are not sufficient to settle this question, just as they do not fully settle the question of where hydrogen and helium should be placed in the periodic table, a point I will return to later.

The elements placed directly under scandium and yttrium in older periodic tables are lanthanum and actinium, but on the basis of electronic configurations lutetium and lawrencium have as much right to occupy these two places.

The trouble began when yet another element, ytterbium, the one before lutetium, was assigned a revised electronic configuration of 4f14 6s2 as its two outer most orbitals. The configuration of lutetium did not change and since it consisted of 4f14 5d1 6s2 this meant that lutetium could now be considered as the first element in the third row of the d-block, and ytterbium as the final member of the lanthanide series.

One possible resolution comes from considering the long-form or 32 column wide periodic table, as compared with the more usual 18 element wide or medium-long form. If one tries to construct the long-form table it is lutetium and lawrencium that fall more naturally under scandium and yttrium in group 3. If one insists on placing lanthanum and actinium in group 3 the atomic number ordering becomes highly irregular.

But this fact has not convinced everyone and nor have the numerous chemical and physical similarities that exist when lutetium and lawrencium are considered as homologues of scandium and yttrium. To make matters worse, the configuration of this week's element, lawrencium, has now been revised as a result of some calculations that include quantum relativistic effects. Although it has not been possible to make even indirect observations of this configuration, the calculations strongly suggest that the most energetic electron in the atom of lawrencium is in a 7p orbital and not 6d orbital as previously believed.

The official governing body, the International Union of Pure and Applied Chemistry has so far refused to take sides on the question of which elements make up group 3. They maintain that they only preside over questions regarding the discovery of new elements and the assigning of new names to elements.

Meanwhile the debate has been waged rather vigorously in the pages of the Journal of Chemical Education where several authors, including myself, have aired their opposing views. It is strange to think that even today the placement of not just one, but two elements remains in doubt. And this is not to mention the related debates in which some experts argue, rather plausibly, that hydrogen should be placed at the top of the halogen group and helium should be moved to the head of the alkaline earth metals.

Clearly the periodic table, and the elements, still hold many surprises in store for us.

Meera Senthilingam

So although that's it for the chemicals currently found in the periodic table, there may still be changes and additions to look out for in the future. That was UCLA scientist and author with the undecided chemistry of lawrencium.

Now that's it for this series of Chemistry in its element, bringing you the discovery, tales and chemistry of course of the chemical elements. But don't fear, we're back next week with a whole new series looking into the exciting and complex world of chemical compounds. So join us then to find out more. But until the new series, thank you for listening. I'm Meera Senthilingam.

(Promo)

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

(End promo)
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Resources

Learn Chemistry: Your single route to hundreds of free-to-access chemistry teaching resources.
 

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References

Visual Elements images and videos
© Murray Robertson 1998-2017.

 

Data

W. M. Haynes, ed., CRC Handbook of Chemistry and Physics, CRC Press/Taylor and Francis, Boca Raton, FL, 95th Edition, Internet Version 2015, accessed December 2014.
Tables of Physical & Chemical Constants, Kaye & Laby Online, 16th edition, 1995. Version 1.0 (2005), accessed December 2014.
J. S. Coursey, D. J. Schwab, J. J. Tsai, and R. A. Dragoset, Atomic Weights and Isotopic Compositions (version 4.1), 2015, National Institute of Standards and Technology, Gaithersburg, MD, accessed November 2016.
T. L. Cottrell, The Strengths of Chemical Bonds, Butterworth, London, 1954.

 

Uses and properties

John Emsley, Nature’s Building Blocks: An A-Z Guide to the Elements, Oxford University Press, New York, 2nd Edition, 2011.
Thomas Jefferson National Accelerator Facility - Office of Science Education, It’s Elemental - The Periodic Table of Elements, accessed December 2014.
Periodic Table of Videos, accessed December 2014.

 

Supply risk data

Derived in part from material provided by the British Geological Survey © NERC.

 

History text

Elements 1-112, 114, 116 and 117 © John Emsley 2012. Elements 113, 115, 117 and 118 © Royal Society of Chemistry 2017.

 

Podcasts

Produced by The Naked Scientists.

 

Periodic Table of Videos

Created by video journalist Brady Haran working with chemists at The University of Nottingham.