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 18  Melting point −248.59°C, −415.46°F, 24.56 K 
Period Boiling point −246.046°C, −410.883°F, 27.104 K 
Block Density (g cm−3) 0.000825 
Atomic number 10  Relative atomic mass 20.180  
State at 20°C Gas  Key isotopes 20Ne 
Electron configuration [He] 2s22p6  CAS number 7440-01-9 
ChemSpider ID 22377 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 images of Las Vegas and the neon ‘dollar’ symbol reflect the use of the gas in neon lighting for advertising.
Appearance
A colourless, odourless gas. Neon will not react with any other substance.
Uses
The largest use of neon is in making the ubiquitous ‘neon signs’ for advertising. In a vacuum discharge tube neon glows a reddish orange colour. Only the red signs actually contain pure neon. Others contain different gases to give different colours.

Neon is also used to make high-voltage indicators and switching gear, lightning arresters, diving equipment and lasers.

Liquid neon is an important cryogenic refrigerant. It has over 40 times more refrigerating capacity per unit volume than liquid helium, and more than 3 times that of liquid hydrogen.
Biological role
Neon has no known biological role. It is non-toxic.
Natural abundance
Neon is the fifth most abundant element in the universe. However, it is present in the Earth’s atmosphere at a concentration of just 18 parts per million. It is extracted by fractional distillation of liquid air. This gives a fraction that contains both helium and neon. The helium is removed from the mixture with activated charcoal.
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History

In 1898, William Ramsay and Morris Travers at University College London isolated krypton gas by evaporating liquid argon. They had been expecting to find a lighter gas which would fit a niche above argon in the periodic table of the elements. They then repeated their experiment, this time allowing solid argon to evaporate slowly under reduced pressure and collected the gas which came off first. This time they were successful, and when they put a sample of the new gas into their atomic spectrometer it startled them by the brilliant red glow that we now associate with neon signs. Ramsay named the new gas neon, basing it on neos, the Greek word for new.
 
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) 1.54 Covalent radius (Å) 0.62
Electron affinity (kJ mol−1) Not stable Electronegativity
(Pauling scale)
Unknown
Ionisation energies
(kJ mol−1)
 
1st
2080.662
2nd
3952.325
3rd
6121.99
4th
9370.66
5th
12177.41
6th
15237.93
7th
19999.086
8th
23069.539
 

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
Isotopes Isotope Atomic mass Natural abundance (%) Half life Mode of decay
  20Ne 19.992 90.48
  21Ne 20.994 0.27
  22Ne 21.991 9.25
 

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.


Supply risk

Relative supply risk Unknown
Crustal abundance (ppm) 0.005
Recycling rate (%) Unknown
Substitutability Unknown
Production concentration (%) Unknown
Reserve distribution (%) Unknown
Top 3 producers
  • Unknown
Top 3 reserve holders
  • Unknown
Political stability of top producer Unknown
Political stability of top reserve holder Unknown
 

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)
1030 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 Neon Podcast
Transcript :

Chemistry in its element: neon


(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, we meet the element that made the red light district what it is today, well sort of; what you're sure to see is a blaze of neon signs and with the story of how they came to be, here's Victoria Gill.

Victoria Gill

This could be the most captivating element of the periodic table. It's the gas that can give you your name or any word you like, in fact, in light. Neon gas filled the first illuminated science, which were produced almost a Century ago and since then, it has infiltrated language and culture. The word conjures up images of colourful or sometimes rather seedy, glowing science, many of which now don't contain the gas itself. Only the red glow is pure neon, almost every other colour is now produced using argon, mercury and phosphorus in varying proportions, which gives more than a 150 possible colours. Nevertheless, it's neon that's now a generic name for all the glowing tubes that allow advertisers and even many artists to draw and write with light and it was that glow that gave its presence away for the first time. 

Before it was isolated, the space it left in the periodic table was the source of years of frustration. With his discovery of Argon in 1894 and the isolation of helium that followed in 1895, the British chemist, Sir William Ramsay had found the first and the third members of the group of inert gases. To fill the gap, he needed to find the second. Finally, in 1898 at University College, London, Ramsay and his colleague, Morris Travers modified an experiment they tried previously, they allowed solid argon surrounded by liquid air to evaporate slowly under reduced pressure and collected the gas that came off first. When they put the sample of their newly discovered gas into an atomic spectrometer, heating it up, they were startled by its glowing brilliance. Travers wrote of this discovery, "the blaze of crimson light from the tube told its own story and was a sight to dwell upon and never forget." The name neon comes from the Greek, neos meaning new. It was actually Ramsey's thirteen year old son, who suggested the name for the gas, saying he would like to call it novum from the Latin word for new. His father liked the idea, but preferred to use the Greek. So a new element in name and nature, finally took its place in the periodic table. And initially its lack of reactivity meant there were no obvious uses for Neon. 

It took a bit of imagination from the French engineer, chemist and inventor, Georges Claude, who early in the 20th Century first applied an electric discharge to a sealed tube of neon gas. The red glow it produced, gave Claude the idea of manufacturing a source of light in an entirely new way. He made glass tubes of Neon, which could be used just like light bulbs. Claude displayed the first neon lamp to the public on December 11th, 1910 at an exhibition in Paris. His striking display turned heads but unfortunately sold no neon tubes. People simply didn't want to illuminate their homes with red light; but Claude wasn't deterred. He patented his invention in 1915 and during his quest to find a use for it he discovered that by bending the tubes, he could make letters that glowed. The use of neon tubes for advertising signs began in 1923, when his company Claude Neon, introduced the gas filled tubular signs to the United States. He sold two to a Packard car dealership in Los Angeles. The first neon signs were dubbed 'liquid fire' and people would stop in the street to stare at them, even in daylight, they glow visibly. These days neon is extracted from liquid air by fractional distillation and just a few tons a year of the abundantly available gas is enough to satisfy any commercial needs. And of course there are now many sources of illuminated signs, screens and displays that give us far more impressive scrolling letters and moving pictures that we associate with the bright colourful lights of say Times Square in New York City.

So Neon might have lost some of its unique lustre here on Earth, but further away, it has helped reveal some secretes of the most important glowing object for our planet, the Sun. Solar particles or solar wind also contain Neon in the ratio of two neon isotopes in Moon rock samples, rocks that get blasted by the solar wind for billions of years had until recently baffled scientists. This is because the ratio of the two isotopes varied according to the depths in the rock; with more neon-22 than neon-20 at lower depths. So did this mean that the sun had once been significantly more active than it is today, shooting out higher energy particles that could penetrate deeper into the rocks? This question was finally answered when scientists studied a piece of metallic glass that had been exposed to the solar wind for just two years on the Genesis spacecraft, which crashed to Earth in 2004. When scientists measured the distribution of Neon in the glass samples, exposed to solar wind, they found the top layer also contained more neon-20 than the underlying layer. The underlying layer was similar to the moon rock. Since the activity of the sun was very unlikely to have changed during the two-year mission, it seems that a type of space erosion was causing the discrepancy, micrometeoroids or the particles simply removed some of the original neon from the top surface of the lunar rock.

So may be you should stop and dwell upon the next neon sign you see and just appreciate a truly unique glow.

Chris Smith

So, an element that's as at home in outer space, as it is advertising a brand name here on Earth. That was Victoria Gill with the story of neon. Next time, to the chemical that ironed out the wrinkles in steel making.

Ron Caspi

When Sir Henry Bessemer invented the process of steel making in 1856, his steel broke up when hot rolled or forged; the problem was solved later that year, when Robert Foster Mushet, another Englishman, discovered that adding small amounts of manganese to the molten iron solves the problem. Since manganese has a greater affinity for sulfur than does iron, it converts the low-melting iron sulfide in steel to high-melting manganese sulfide.

Chris Smith

But how did it work, Ron Caspi will be here next week with the story of manganese, the element that makes photosynthesis feasible and gave us an alternative to green glass. That's on next week's Chemistry in its element; I hope you can join us. I'm Chris Smith, thank you for listening and goodbye!

(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.