Terminology

Allotropes
Some elements exist in several different structural forms, these are called allotropes.

For more information on Murray Robertson’s image see Uses/Interesting Facts below.

Carbon

Discovery date	Prehistoric
Discovered by	-
Origin of the name	The name is derived from the Latin ‘carbo’, charcoal
Allotropes	diamond, graphite, graphene, amorphous, fullerene

12.011

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	14	Melting point	3825 ^oC, 6917 ^oF, 4098.15 K
Period	2	Boiling point	Sublimes
Block	p	Density (kg m^-3)	35.13 (diamond); 2.267 (graphite)
Atomic number	6	Relative atomic mass	12.011
State at room temperature	Solid	Key isotopes	¹²C, ¹³C, ¹⁴C
Electron configuration	[He] 2s²2p²	CAS number	7440-44-0:1333-86-4
ChemSpider ID	4575370	ChemSpider is a free chemical structure database

Interesting Facts 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 / Interesting Facts

Image explanation

Carbon is often referred to as the "King of the Elements" due to is extensive uses, its importance in life applications such as DNA, and also because this element can come in various forms, each form providing a unique function. The three crowns represent the three states of Carbon in nature, plus the suggestion of a heraldic motif, emphasise Carbon’s regal status in the Periodic Table.

Appearance

There are a number of pure forms of this element including graphite and diamond. In 1985, a new one was discovered consisting of ‘footballs’ of carbon atoms, now known as fullerenes. The element itself is used as coke in steel making to reduce iron oxide to iron, as carbon black in printing, and as charcoal in sugar refining. However, carbon is also the basis of all life since it is part of DNA and proteins etc. The human body contains about 16 kilogrammes of carbon in one form or another. Carbon is also important environmentally as carbon dioxide; it is about 350 parts per million of the atmosphere, and plants take it in as they grow. Carbon dioxide is also the gas formed when natural gas, oil and coal are burned.

Uses

Carbon is unique among the elements in the vast member and variety of compounds it can form. With hydrogen, oxygen, nitrogen and other elements it forms very large numbers of compounds, carbon atom often being linked to another carbon atom. This ability to form chains is unique to carbon, and it is thought to be an important reason for the dependence of life. It is also an indispensable source of such varied everyday products as Nylon and petrol, perfume and plastics, shoe polish, DDT and TNT.

Biological role

Carbon is the basis of all life as part and the human body contains about 16 kilogrammes of carbon in one form or another. Carbon is a major component of the DNA molecule. There are several million known carbon compounds, many thousands of which are vital to organic and life processes. Carbon is also important environmentally as carbon dioxide; it is about 350 parts per million of the atmosphere, and plants take it in as they grow.

Natural abundance

Carbon is found in abundance in the sun, stars, comets and atmospheres of most planets. Graphite is found naturally in many locations. Diamond is found in the form of microscopic crystals in some meteorites. Natural diamonds are found in the mineral kimberlite, sources of which are in South Africa, Arkansas and elsewhere. Diamonds are now also being recovered from the ocean floor off the Cape of Good Hope. About 30% of all industrial diamonds used in the United States are made synthetically. Carbon is found in combination in hydrocarbons (methane gas, oil and coal), and carbonates (limestone and dolomite). The element itself is used as coke in steel making to reduce iron oxide to iron, as carbon black in printing, and as charcoal in sugar refining.

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, E_d in eV. χ_A - χ_B =(eV)-1/2sqrt(E_d(AB)-[E_d(AA)+E_d(BB)]/2), with χ_H set as 2.2 (where several isotopes exist, a value is presented for the most prevalent isotope).

1^st 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)	1.700	Covalent radius (Å)	0.75
Electron affinity (kJ mol^-1)	121.733	Electronegativity (Pauling scale)	2.550
Ionisation energies (kJ mol^-1)	1^st 1086.453 2^nd 2352.629 3^rd 4620.467 4^th 6222.711 5^th 37830.615 6^th 47277.133 7^th - 8^th -

Bonding and Enthalpies terminology

Covalent Bonds
The strengths of several common covalent bonds.

Bonding / Enthalpies

Covalent bonds

C–C 347 kJ mol ^-1	C=C 612 kJ mol ^-1	C≡C 838 kJ mol ^-1
C–H 413 kJ mol ^-1	C–H 435 kJ mol ^-1	C–F 467 kJ mol ^-1
C–F 452 kJ mol ^-1	C–F 485 kJ mol ^-1	C–Cl 346 kJ mol ^-1
C–Cl 327 kJ mol ^-1	C–Br 290 kJ mol ^-1	C–Br 285 kJ mol ^-1
C–I 228 kJ mol ^-1	C–I 234 kJ mol ^-1	C–N 286 kJ mol ^-1
C=N 615 kJ mol ^-1	C≡N 887 kJ mol ^-1	C–O 358 kJ mol ^-1
C–O 336 kJ mol ^-1	C=O 805 kJ mol ^-1	C=O 695 kJ mol ^-1
C=O 736 kJ mol ^-1	C=O 749 kJ mol ^-1	C≡O 1077 kJ mol ^-1
C–Si 307 kJ mol ^-1

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

Coal

Scarcity factor	4.5
Country with largest reserve base	USA
Crustal abundance (ppm)	200
Leading producer	China
Reserve base distribution (%)	27.50
Production concentration (%)	46.10
Total governance factor(production)	8

Top 3 countries (mined)	1) USA 2) Russia 3) China
Top 3 countries (production)	1) China 2) USA 3) India

Diamond

Scarcity factor	4.0
Country with largest reserve base	DRC
Crustal abundance (ppm)	200
Leading producer	Russia
Reserve base distribution (%)	33.50
Production concentration (%)	28.60
Total governance factor(production)	7

Top 3 countries (mined)	1) DRC 2) Australia 3) Botswana
Top 3 countries (production)	1) Russia 2) DRC 3) Botswana

Graphite

Scarcity factor	7.0
Country with largest reserve base	China
Crustal abundance (ppm)	200
Leading producer	China
Reserve base distribution (%)	63.60
Production concentration (%)	81.80
Total governance factor(production)	8

Top 3 countries (mined)	1) China 2) Czech Republic 3) India
Top 3 countries (production)	1) China 2) Bosnia-Herzegovina 3) Brazil

Oxidation states/ 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.

Oxidation States / Isotopes

Common oxidation states	4,3,2,1,0,-1,- 2,-3,-4
Isotopes	Isotope	Atomic mass	Natural abundance (%)	Half life	Mode of decay
	¹²C	12	98.93	-	-
	¹³C	13.003	1.07	-	-
	¹⁴C	14.003	-	5717 y	β-

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 / Temperature - Advanced

Molar heat capacity
(J mol^-1 K^-1)

6.155 (diamond); 8.517 (graphite)

Young's modulus (GPa)

1050 (diamond)

Shear modulus (GPa)

478 (diamond)

Bulk modulus (GPa)

542 (diamond);33 (graphite)

Vapour pressure

Temperature (K)

400

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1400

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2000

2200

2400

Pressure (Pa)

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Video

Videos of the elements. Additional videos will be coming in 2012.

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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.
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.

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