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.

Phosphorus

Discovery date	1669
Discovered by	Hennig Brandt
Origin of the name	The name is derived from the Greek 'phosphoros', meaning bringer of light.
Allotropes	White P, Red P, Black P, P₂

30.974

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	15	Melting point	44.15 ^oC, 111.47 ^oF, 317.3 K
Period	3	Boiling point	280.5 ^oC, 536.9 ^oF, 553.65 K
Block	p	Density (kg m^-3)	1820 (yellow)
Atomic number	15	Relative atomic mass	30.974
State at room temperature	Solid	Key isotopes	³¹P
Electron configuration	[Ne] 3s²3p³	CAS number	7723-14-0
ChemSpider ID	4575369	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

The image represents a polyhedral model of white phosphorus. The tetrahedron represents the bonding in the molecule. Click through to the alchemical symbol for Phosphorus and other elements.

Appearance

There are several forms of phosphorus. White phosphorus is manufactured industrially, glows in the dark, is spontaneously flammable when exposed to air above 30°C and is a deadly poison. Red phosphorus, made by gently heating white phosphorus to about 250°C in the absence of air, does not glow, is stable and is not poisonous. This is the material, mixed with powdered glass, stuck on the side of boxes of safety matches on which the matches must be struck to light them. Phosphorus itself is essential to all forms of life since it is part of DNA, although there are many phosphorus compounds that are essential in the living cell. We take in about 1 gramme of phosphate a day, and we store about 750 grammes in our bodies, since our bones are mainly calcium phosphate. In the environment and in living things, phosphorus is present as phosphate, which consists of one phosphorus atom at the centre of four oxygen atoms. Phosphates are used in fertilisers and detergents and in metal coatings to prevent corrosion. However, excess phosphates in rivers and lakes cause an over-growth of slimy green algae, which robs the water of its life-supporting oxygen.

Uses

Many fertilisers contain a high proportion of phosphorus and are manufactured from concentrated phosphoric acids. Worldwide demand for fertilisers has greatly increased in recent years as their importance to agriculture and farming has grown. Phosphorus is also important in the production of steel. Phosphates are ingredients of some detergents, but are increasingly being omitted nowadays due to concern that high phosphate levels in natural water supplies cause the growth of undesirable algae. Phosphates are also used in the production of special glasses and fine chinaware.

Biological role

Phosphorus is the basis of life as part of the DNA molecule. We take in about 1 gramme of phosphate a day, and we store about 750 grammes in our bodies, since our bones are mainly calcium phosphate. In the environment and in living things, phosphorus is present as phosphate, which consists of one phosphorus atom at the centre of four oxygen atoms. However, excess phosphates in rivers and lakes cause an over-growth of slimy green algae, which robs the water of its life-supporting oxygen. White phosphorus is very toxic and contact with skin can cause severe burns.

Natural abundance

Phosphorus is not found uncombined in nature, but is widely distributed in combination with minerals. An important source is phosphate rock, which contains the apatite minerals and is found in large quantities in the USA and elsewhere. There are several forms of phosphorus. White phosphorus is manufactured industrially by several methods, glows in the dark, is spontaneously flammable when exposed to air above 30°C and is a deadly poison. Red phosphorus, made by gently heating white phosphorus to about 250°C in the absence of air, does not glow, is stable and is not poisonous. Usually phosphate rock is heated in the presence of carbon and silica in a furnace, which produces phosphorus as a vapour which is then collected under water. It can then be converted to red phosphorus by heating for several days.

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)	1.800	Covalent radius (Å)	1.09
Electron affinity (kJ mol^-1)	72.075	Electronegativity (Pauling scale)	2.190
Ionisation energies (kJ mol^-1)	1^st 1011.811 2^nd 1907.465 3^rd 2914.115 4^th 4963.578 5^th 6273.963 6^th 21267.377 7^th 25430.619 8^th 29871.836

Bonding and Enthalpies terminology

Covalent Bonds
The strengths of several common covalent bonds.

Bonding / Enthalpies

Covalent bonds

H–P 321 kJ mol ^-1	N≡P 582 kJ mol ^-1	P–P 198 kJ mol ^-1
P≡P 485 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

Scarcity factor	5.0
Country with largest reserve base	Morocco
Crustal abundance (ppm)	567
Leading producer	China
Reserve base distribution (%)	44.70
Production concentration (%)	38.50
Total governance factor(production)	9

Top 3 countries (mined)	1) Morocco 2) China 3) USA
Top 3 countries (production)	1) China 2) Mexico 3) Morocco

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	5, 3, -3
Isotopes	Isotope	Atomic mass	Natural abundance (%)	Half life	Mode of decay
	³¹P	30.974	100	-	-

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)

23.824

Young's modulus (GPa)

Unknown

Shear modulus (GPa)

Unknown

Bulk modulus (GPa)

10.9 (red); 4.9 (white)

Vapour pressure

Temperature (K)

400

600

800

1000

1200

1400

1600

1800

2000

2200

2400

Pressure (Pa)

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Podcasts

Chemistry World podcast

Chemistry World podcast transcript

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Video

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

Terms & Conditions

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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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