Periodic Table > Nitrogen
 

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 15  Melting point −210.0°C, −346.0°F, 63.2 K 
Period Boiling point −195.795°C, −320.431°F, 77.355 K 
Block Density (g cm−3) 0.001145 
Atomic number Relative atomic mass 14.007  
State at 20°C Gas  Key isotopes 14
Electron configuration [He] 2s22p3  CAS number 7727-37-9 
ChemSpider ID 20473555 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 wheat sheaf symbol and lightning reflect the importance of nitrogen to living things. Nitrogen is important for plant growth and can be ‘fixed’ by lightning or added to soils in fertilisers.
Appearance
A colourless, odourless gas.
Uses
Nitrogen is important to the chemical industry. It is used to make fertilisers, nitric acid, nylon, dyes and explosives. To make these products, nitrogen must first be reacted with hydrogen to produce ammonia. This is done by the Haber process. 150 million tonnes of ammonia are produced in this way every year.

Nitrogen gas is also used to provide an unreactive atmosphere. It is used in this way to preserve foods, and in the electronics industry during the production of transistors and diodes. Large quantities of nitrogen are used in annealing stainless steel and other steel mill products. Annealing is a heat treatment that makes steel easier to work.

Liquid nitrogen is often used as a refrigerant. It is used for storing sperm, eggs and other cells for medical research and reproductive technology. It is also used to rapidly freeze foods, helping them to maintain moisture, colour, flavour and texture.
Biological role
Nitrogen is cycled naturally by living organisms through the ‘nitrogen cycle’. It is taken up by green plants and algae as nitrates, and used to build up the bases needed to construct DNA, RNA and all amino acids. Amino acids are the building blocks of proteins.

Animals obtain their nitrogen by consuming other living things. They digest the proteins and DNA into their constituent bases and amino acids, reforming them for their own use.

Microbes in the soil convert the nitrogen compounds back to nitrates for the plants to re-use. The nitrate supply is also replenished by nitrogen-fixing bacteria that ‘fix’ nitrogen directly from the atmosphere.

Crop yields can be greatly increased by adding chemical fertilisers to the soil, manufactured from ammonia. If used carelessly the fertiliser can leach out of the soil into rivers and lakes, causing algae to grow rapidly. This can block out light preventing photosynthesis. The dissolved oxygen soon gets used up and the river or lake dies.
Natural abundance
Nitrogen makes up 78% of the air, by volume. It is obtained by the distillation of liquid air. Around 45 million tonnes are extracted each year. It is found, as compounds, in all living things and hence also in coal and other fossil fuels.
 
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) 1.55 Covalent radius (Å) 0.71
Electron affinity (kJ mol−1) Not stable Electronegativity
(Pauling scale)
3.04
Ionisation energies
(kJ mol−1)
 
1st
1402.328
2nd
2856.092
3rd
4578.156
4th
7475.057
5th
9444.969
6th
53266.835
7th
64360.16
8th
-
 
Glossary

Bond enthalpy (kJ mol−1)
A measure of how much energy is needed to break all of the bonds of the same type in one mole of gaseous molecules.

Bond enthalpies

 
Covalent bond Enthalpy (kJ mol−1) Found in
N–N 163 N2H4
N=N 418 C6H14N2
N≡N 944.7 N2
C–N 304.6 general
C=N 615 general
C≡N 889.5 general
H–N 390.8 NH3
 

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) 19
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


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 5, 4, 3, 2, -3
Isotopes Isotope Atomic mass Natural abundance (%) Half life Mode of decay
  14N 14.003 99.636
  15N 15.000 0.364
 

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)
1040 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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History

Nitrogen in the form of ammonium chloride, NH4Cl, was known to the alchemists as sal ammonia. It was manufactured in Egypt by heating a mixture of dung, salt and urine. Nitrogen gas itself was obtained in the 1760s by both Henry Cavendish and Joseph Priestley and they did this by removing the oxygen from air. They noted it extinguished a lighted candle and that a mouse breathing it would soon die. Neither man deduced that it was an element. The first person to suggest this was a young student Daniel Rutherford in his doctorate thesis of September 1772 at Edinburgh, Scotland.
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Podcasts

Listen to Nitrogen Podcast
Transcript :

Chemistry in its element: nitrogen


(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 blowing up airbags, asphyxiating animals and getting to the bottom of gunpowder because Cambridge chemist Peter Wothers has been probing the history of nitrogen.

Peter Wothers

Nitrogen gas makes up about 80% of the air we breathe. It's by far the most abundant element in its group in the periodic table and yet it is the last member of its family to be discovered. The other elements in its group, phosphorus, arsenic, antimony and bismuth, had all been discovered, used and abused at least 100 years before nitrogen was known about. It wasn't really until the 18th Century that people focussed their attention on the chemistry of the air and the preparation properties of different gases. We can only really make sense of the discovery of nitrogen by also noting the discovery of some of these other gases. 

Robert Boyle noted in 1670 that when acid was added to iron filings, the mixture grew very hot and belched up copious and stinking fumes. So inflammable it was that upon the approach of a lighted candle to it, it would readily enough take fire and burn with a bluish and somewhat greenish flame. Hydrogen was more carefully prepared and collected by the brilliant but reclusive millionaire scientist Henry Cavendish about a 100 years later. Cavendish called the gas inflammable air from the metals in recognition of this most striking property. He also studied the gas we know call carbon dioxide, which had first been prepared by the Scottish chemist, Joseph Black in the 1750s. Black called carbon dioxide fixed air, since it was thought to be locked up or fixed in certain minerals such as limestone. It could be released from its stony prison by the action of heat or acids. 

Carbon dioxide was also known by the name mephitic air the word mephitic meaning noxious or poisonous. This name obviously came from its property of destroying life, since it rapidly suffocates any animals immersed in it. This is where the confusion with nitrogen gas begins, since pure nitrogen gas is also suffocating to animals. If the oxygen in an enclosed quantity of air is used up, either by burning a candle in it or by confining an animal, most of the oxygen is converted to carbon dioxide gas which mixes with the nitrogen gas present in the air. This noxious mixture no longer supports life and so was called mephitic. 

The crucial experiment in the discovery of nitrogen was when it was realized that there are at least two different kinds of suffocating gases in this mephitic air. This was done by passing the mixture of gases through a solution of alkali, which absorbed the carbon dioxide but left behind the nitrogen gas. Cavendish prepared nitrogen gas by this means. He passed air back and forth over heated charcoal which converted the oxygen in the air to carbon dioxide. The carbon dioxide was then dissolved in alkali leaving behind the inert nitrogen gas, which he correctly observed was slightly less dense than common air. Unfortunately, Cavendish didn't publish his findings. He just communicated them in a letter to fellow scientist, Joseph Priestley, one of the discoverers of oxygen gas. Consequently, the discovery of nitrogen is usually accredited to one of Joseph Black's students, the Scottish scientist, Daniel Rutherford, who's also the uncle of the novelist and poet, Sir Walter Scott. Rutherford published his findings, which was similar to those of Cavendish in his doctoral thesis entitled, "An Inaugural Dissertation on the Air called Fixed or Mephitic" in 1772. 

So what about the name, nitrogen? In the late 1780s, chemical nomenclature underwent a major revolution under the guidance of the French chemist, Antoine Lavoisier. It was he and his colleagues, who suggested many of the names we still use today including the word hydrogen, which comes from the Greek meaning water former and oxygen from the Greek for acid producer, since Lavoisier mistakenly thought that oxygen was the key component of all acids. However, in his list of the then known elements, Lavoisier included the term azote or azotic gas for what we now call nitrogen. This again stems from Greek words, this time meaning the absence of life, once again focussing on its mephitic quality. It was not long before it was pointed out that there are many mephitic gases, in fact no gas other than oxygen can support life. The name nitrogen was therefore proposed from the observation, again first made by Cavendish that if the gases sparked with oxygen, and then the resulting nitrogen dioxide gases passed through alkali, nitre, otherwise known as saltpetre or potassium nitrate is formed. The word nitrogen therefore means nitre former. The derivatives of the word, azote still survive today. The compound used to explosively fill car air bags with gas is sodium azide, a compound of just sodium and nitrogen. When triggered this compound explosively decomposes freeing the nitrogen gas, which inflates the bags. Far from destroying life, this azotic compound has been responsible for saving thousands.

Chris Smith

Cambridge University's Peter Wothers telling the story of the discovery of nitrogen. Next time on Chemistry in its element, how chemists like Mendeleev got to grips with both the known and the unknown.

Mark Peplow

While other scientists had tried to create ways of ordering the known elements, Mendeleev created the system that could predict the existence of elements, not yet discovered. When he presented the table to the world in 1869, it contained four prominent gaps. One of these was just below manganese and Mendeleev predicted that element with atomic weight 43 would be found to fill that gap, but it was not until 1937 that a group of Italian scientists finally found the missing element, which they named technetium.

Chris Smith

And you can hear Mark Peplow telling technetium's tale in next week's edition of 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 :
Some reactions of nitrogen dioxide
Description :
In the beaker are test-tubes containing different gases - carbon dioxide, dinitrogen oxide, oxygen, chlorine and hydrogen. You may remove a test-tube only once and when you do so you must identify the...
Description :
In this demonstration solid white ammonium chloride is formed because of gaseous diffusion.
Description :
Diffusion of gases – a safer alternative to bromine
Description :
Explore chemistry & industrial processes with 15 tutorials, all available on the Alchemy website.
Description :
Increasing levels of carbon dioxide in the atmosphere cause a rise in global temperature. This worksheet looks at some data from other greenhouse gases to see if they have the same effect.
 

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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.