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 14  Melting point 327.462°C, 621.432°F, 600.612 K 
Period Boiling point 1749°C, 3180°F, 2022 K 
Block Density (g cm−3) 11.3 
Atomic number 82  Relative atomic mass 207.2  
State at 20°C Solid  Key isotopes 208Pb 
Electron configuration [Xe] 4f145d106s26p2  CAS number 7439-92-1 
ChemSpider ID 4509317 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
Lead has been known to, and used by, humans for many centuries. This long history is reflected in the image by the use of an early alchemical symbol for lead and carved Ancient Roman characters.
Appearance
A dull, silvery-grey metal. It is soft and easily worked into sheets.
Uses
This easily worked and corrosion-resistant metal has been used for pipes, pewter and paint since Roman times. It has also been used in lead glazes for pottery and, in this century, insecticides, hair dyes and as an anti-knocking additive for petrol. All these uses have now been banned, replaced or discouraged as lead is known to be detrimental to health, particularly that of children.

Lead is still widely used for car batteries, pigments, ammunition, cable sheathing, weights for lifting, weight belts for diving, lead crystal glass, radiation protection and in some solders.

It is often used to store corrosive liquids. It is also sometimes used in architecture, for roofing and in stained glass windows.
Biological role
Lead has no known biological role. It can accumulate in the body and cause serious health problems. It is toxic, teratogenic (disturbs the development of an embryo or foetus) and carcinogenic.

Daily intake of lead from all sources is about 0.1 milligrams. The average human body stores about 120 milligrams of lead in the bones.
Natural abundance
Lead is chiefly obtained from the mineral galena by a roasting process. At least 40% of lead in the UK is recycled from secondary sources such as scrap batteries and pipes.
 
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) 2.02 Covalent radius (Å) 1.45
Electron affinity (kJ mol−1) 35.121 Electronegativity
(Pauling scale)
1.8
Ionisation energies
(kJ mol−1)
 
1st
715.596
2nd
1450.414
3rd
3081.481
4th
4083.26
5th
6638.2
6th
-
7th
-
8th
-
 

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 6.2
Crustal abundance (ppm) 11
Recycling rate (%) >30
Substitutability Unknown
Production concentration (%) 44
Reserve distribution (%) 34
Top 3 producers
  • 1) China
  • 2) Australia
  • 3) USA
Top 3 reserve holders
  • 1) Australia
  • 2) China
  • 3) Russia
Political stability of top producer 24.1
Political stability of top reserve holder 74.5
 

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 4, 2
Isotopes Isotope Atomic mass Natural abundance (%) Half life Mode of decay
  204Pb 203.973 1.4
  206Pb 205.974 24.1
  207Pb 206.976 22.1
  208Pb 207.977 52.4 > 2 x 1019 sf 
 

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)
130 Young's modulus (GPa) 16.1
Shear modulus (GPa) 5.59 Bulk modulus (GPa) 45.8
Vapour pressure  
Temperature (K)
400 600 800 1000 1200 1400 1600 1800 2000 2200 2400
Pressure (Pa)
- 5.54
x 10-7
0.00618 1.64 68.1 - - - - - -
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History

Lead has been mined for more than 6,000 years, and the metal and its compounds have been used throughout history. Small lead nuggets have been found in pre-Columbian Peru, Yucatan, and Guatemala.

The Greeks mined lead on a large scale from 650 onwards and not only knew how to obtain the metal but how to covert this to white lead. Because of its superb covering power, this was the basis of paints for more than 2000 years, until the middle of the last century.

The Romans employed lead on a large scale, mining it mainly in Spain and Britain, and using it also for water pipes, coffins, pewter tableware, and to debase their silver coinage. While its mining declined in the Dark Ages it reappeared in Medieval times and found new uses, such as pottery glazes, bullets, and printing type. In the last century it was a fuel additive.
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Podcasts

Listen to Lead Podcast
Transcript :

Chemistry in its element: lead


(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're sinking to new depths as we meet the metal that spawned the plumb line, a rock group, plumbing and even poisoning, not to mention a generation of alchemists who tried in vain to turn this substance into gold. It is of course lead, and here to swing it for us is science writer Phil Ball.

Phil Ball

Lead is the Eeyore of metals - slow, dull and heavy. In its Latin form, plumbum, it enters our vocabulary by virtue of its soft and ponderous character: we once plumbed depths with a suspended grey blob of the stuff, emphatically commanded by gravity, while plumbers have long since traded their malleable lead pipes for plastic. Everything associated with lead tends towards over-burdened gloom: in the ancient scheme of metal symbolism, lead was linked to Saturn, the melancholy planet, personified by the old god also called Cronos who castrated his father and swallowed his children. Even the spark of glamour the metal gets from association with the world's greatest rock band stems from the Eeyorish prediction that they would sink like a lead balloon or zeppelin.

Yes, lead is the original heavy metal, the most notorious offender in that toxic group. Lead damages the brain and the kidneys, it can cause anaemia and a form of gout with the doleful title of saturnine gout. Even the Romans knew about lead poisoning - the doctor Cornelius Celsus warned about the bad effects of lead white, used in paint and cosmetics, while the engineer Vitruvius recommended earthenware pipes over lead ones. Yet we were slow to learn. Lead white, a form of lead carbonate, remained the artist's best white pigment right up until the nineteenth century, when it was replaced by zinc white. As paint manufacture became industrialized, lead white spread sickness and death among factory workers: a report in the Transactions of the Royal Society in the seventeenth century listed vertigo, dizziness, blindness, stupidity and paralytic affections among the conditions it caused.

And as late as in 2007 the toy manufacturer Mattel was forced to recall millions of toys made in China that had been coloured with lead paint. Meanwhile, a toxic trickle of lead from solder and the electrodes of batteries leaches slowly from landfill sites throughout the world. In 2006 the European Union effectively banned lead from most consumer electronics, but it remains in use elsewhere.

To alchemists, lead was the lowliest of metals - in a sense, it was where all metals started. In talk of base metals, which alchemy tried to turn to silver and gold, there was none so base as lead. The alchemists believed that lead slowly matured into other metals in the ground. But alchemy also offered lead a chance to shake off its grey and graceless image. It does not take much to draw splendid colours out of lead. The ancient technologists blanched the dull metal by placing lead strips in pots with vinegar, and shutting them away in a shed full of animal dung. The vinegar fumes and gas from fermenting dung conspired to corrode lead into lead white. Heat this gently, and it turns yellow: a form of lead oxide known as litharge or, in the Middle Ages, massicot. Heat it some more, and it goes bright red, as you form a different kind of oxide. Both of these substances were used by artists - red lead was, for a long time, their finest red, used for painting many a bright robe in the Middle Ages. It was the signature colour of Saint Jerome.

To the alchemists, those colour changes weren't just a way to make pigments. They signified some more profound alteration taking place in the metal, bringing it close to the colour of gold. It's no wonder, then, that their experiments often began with lead. They came no closer to making real gold, but they started to explore the processes of chemical transformation.

Lead, however, seems habituated to revealing its true and dirty colours. Exposed to air, it may go on taking up oxygen until it turns black. Red lead has become chocolate brown on paintings throughout the world, from Japan to India to Switzerland. In urban galleries there is another danger, as the sulfurous fumes of pollution react with red lead to from black lead sulphide. There seems to be no getting away from it: lead has a glum and melancholy heart.

Chris Smith

Phil Ball plumbing the depths of the scientific story of lead. The next edition of Chemistry in its element promises to be a record breaker.

Mark Peplow

You can learn a lot about someone by meeting their family and the same is true for the element. That's how we come to know so much about astatine. Often trumpeted as the rarest naturally occurring element in the world, it's been estimated that the top kilometre of the earth's crust contains less than 50 mg of astatine making it Guinness world record's rarest element.

Chris Smith

And you can hear Mark Peplow telling the tale of the world's rarest chemical in next week's Chemistry in its element. 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.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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  Help Text

Resources

Description :
We discover how to extract lead from lead(II) oxide. We mix lead(II) oxide with charcoal powder and then heat the mixture using a Bunsen burner. It glows bright red as a reaction occurs and after a fe...
Description :
An introduction to the common elements found in the Earth's crust. This can be used to underpin topics on useful materials from the Earth and on the extraction of metals.
Description :
Gives information about the most common elements in the Earth’s crust and the other the chemical composition of some minerals.
Description :
Solder can be made by heating together the metals lead and tin. The hardness, melting point and density of the alloy can be compared to lead.
Description :
This extraction experiment consists of two competition reactions. A metal oxide is reacted with charcoal. If the charcoal (carbon) is more reactive it will remove the oxygen from the metal oxide and l...
Description :
The halogens are elements of Group 7 of the Periodic table. This experiment illustrates some of the trends within the compounds of this group. It is ideal for discussing ionic equations, making predic...
 

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References

 
Visual Elements images and videos
© Murray Robertson 2011.

 

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 3.0), 2010, National Institute of Standards and Technology, Gaithersburg, MD, accessed December 2014.
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

© John Emsley 2012.

 

Podcasts

Produced by The Naked Scientists.

 

Periodic Table of Videos

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