Periodic Table > Fluorine
 

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.

 

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 17  Melting point -219.67 oC, -363.406 oF, 53.48 K 
Period Boiling point -188.11 oC, -306.598 oF, 85.04 K 
Block Density (kg m-3) 1140 (73 K) 
Atomic number Relative atomic mass 18.998  
State at room temperature Gas  Key isotopes 19
Electron configuration [He] 2s22p5  CAS number 7782-41-4 
ChemSpider ID 4514530 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
Image reflects the highly reactive nature of the element.
Appearance

Vey pale yellow green dangerously reactive gas.

Source

Uses

Fluorine salts, known as fluorides, were used for centuries in welding metals and for frosting glass before the element itself was isolated.  There was no commercial production of fluorine until World War II, when the production of the atom bomb and other nuclear energy projects made it necessary to produce large quantities. The element is used to make uranium hexafluoride, needed by the nuclear power industry to separate uranium isotopes, and sulfur hexafluoride, the insulating gas for high-power electricity transformers. It is also used in many fluorochemicals, including high-temperature plastics, especially Teflon. Hydrofluoric acid is used for etching the glass of light bulbs and in similar applications, Fluorine gas is the most reactive of all the elements and quickly attacks all metals - steel wool bursts into flames when exposed to it. CFC’s (Fluoro-chloro-carbons) were once used as aerosol propellants, and refrigerants and for ‘blowing’ expanded polystyrene, however their inertness enabled them to diffuse into the stratosphere where they were responsible for the destructing of ozone. Now banned they have been replaced by hydro-fluoro-carbons.

Biological role

Fluoride is an essential ion for animals, strengthening teeth and bones. The presence of fluorides below 2ppm in drinking water is believed to prevent dental cavities, but above this concentration may cause mottled enamel in children while they are acquiring permanent teeth. It is added to drinking water in some areas and to toothpaste. The average human body contains about 3 milligrams; too much fluoride is toxic. Elemental fluorine is highly toxic.

Natural abundance

Fluorine occurs chiefly in the minerals fluorite, fluorspar and cryolite, but is rather widely distributed in other minerals. It is the 13th most abundant element in the earth’s crust.

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


1st 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) 1.470 Covalent radius (Å) 0.6
Electron affinity (kJ mol-1) 328.147 Electronegativity
(Pauling scale)
3.980
Ionisation energies
(kJ mol-1)
 
1st
1681.045
2nd
3374.167
3rd
6050.436
4th
8407.706
5th
11022.746
6th
15164.115
7th
17867.719
8th
92038.367
 
Bonding and Enthalpies terminology

Covalent Bonds
The strengths of several common covalent bonds.

Bonding / Enthalpies

 
Covalent bonds
F–F  158  kJ mol -1 H–F  568  kJ mol -1 C–F  467  kJ mol -1
C–F  452  kJ mol -1 C–F  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 4.5
Country with largest reserve base China
Crustal abundance (ppm) 553
Leading producer China
Reserve base distribution (%) n/a
Production concentration (%) 54.90
Total governance factor(production) 8
Top 3 countries (mined)
  • 1) China
  • 2) South Africa
  • 3) Mexico
Top 3 countries (production)
  • 1) China
  • 2) Mexico
  • 3) Mongolia
 

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.


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.

Oxidation States / Isotopes

 
Common oxidation states -1
Isotopes Isotope Atomic mass Natural abundance (%) Half life Mode of decay
  19F 18.998 100
 

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)
31.304 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

The early chemists were aware that metal fluorides contained an unidentified element similar to chlorine, but they could not isolate it. (The French scientist, André Ampère coined the name fluorine in 1812.) Even the great Humphry Davy was unable to produce the element, and he became ill by trying to isolate it from hydrofluoric acid.


The British chemist George Gore in 1869 passed an electric current through liquid HF but found that the gas which was liberated reacted violently with his apparatus. He thought it was fluorine but was unable to collect it and prove it. Then in 1886 the French chemist Henri Moissan obtained it by the electrolysis of potassium bifluoride (KHF2) dissolved in liquid HF.

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Podcasts

Listen to Fluorine Podcast
Transcript :

Chemistry in its element - fluorine


  (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

 

This week, a strong acid it's not, but deadly it definitely is.

 

Kira J. Weissman

The 37-year old technician spilled only a few hundred milliliters or so in his lap during a routine palaeontology experiment.   He took the normal precaution in such situations, quickly dowsing himself with water from a laboratory hose, and even plunged into a nearby swimming pool while the paramedics were en route.   But a week later, doctors removed a leg, and a week after that, he was dead.   The culprit: hydrofluoric acid (colloquially known as HF), and the unfortunate man was not its first victim.  

 

Unlike its close relatives, hydrochloric and hydrobromic acid, HF is a weak acid.   This, coupled with its small molecular size, allows it to penetrate the skin and migrate rapidly towards the deeper tissue layers.   Once past the epidermis, HF starts to dissociate, unleashing the highly-reactive fluoride ion.   Free fluoride binds tightly to both calcium and magnesium, forming insoluble salts which precipitate into the surrounding tissues.   Robbed of their co-factors, critical metabolic enzymes can no longer function, cells begin to die, tissues to liquefy and bone to corrode away.   And if calcium loss is rapid enough, muscles such as the heart stop working.   Burns with concentrated HF involving as little as 2.5% of the body surface area - the size of the sole of the foot, for example - have been fatal.   

                                                                                        

HF has a long history of destructive behaviour, claiming the lives of several chemists in the 1800s, including the Belgian Paulin Louyet, and the Frenchman Jérôme Nicklès.   These brave scientists were battling to be the first to isolate elemental fluorine (F2) from its various compounds, using electrolysis.   However, it was Nicklès' countrymen, Henri Moissan, who succeeded in 1886.   To achieve this feat, Moissan not only had to contend with HF - the preferred electrolyte in such experiments - but fluorine itself, a violently reactive gas.   His key innovation was to construct an apparatus out of platinum, one of the few metals capable of resisting attack, while cooling the electrolytic solution down to -50 °C to limit corrosion.   Moissan's feat earned him the 1906 Nobel Prize in chemistry, but the celebration was short-lived.   Another victim of fluorine's toxic effects, he died only two months later.   Yet Moissan's method lived on, and is used today to produce multi-ton quantities of fluorine from its ore fluorspar.

 

Ironically, while elemental fluorine is decidedly bad for your health, fluorine atoms turns up in some 20% of all pharmaceuticals.   The top-selling anti-depressant Prozac, the cholesterol-lowering drug Lipitor, and the antibacterial Cipro, all have fluorine to thank for their success.   How is this possible?   Because the flip side of fluorine's extreme reactivity is the strength of the bonds it forms with other atoms, notably including carbon.   This property makes organofluorine compounds some of the most stable and inert substances known to man.   Fluorine's special status also stems from the 'fluorine factor', the ability of this little atom to fine-tune the chemical properties of an entire molecule.   For example, replacing hydrogen with fluorine can protect drugs from degradation by metabolic enzymes, extending their active lifetimes inside the body.   Or the introduced fluorine can alter a molecule's shape so that it binds better to its target protein.   Such precise chemical tinkering can now be carried out in pharmaceutical labs using an array of safe, commercially-available fluorinating agents, or the tricky transformations can simply be out-sourced to someone else.

 

Most of us also have fluorine to thank for our beaming smiles.   The cavity-fighting agents in toothpaste are inorganic fluorides such as sodium fluoride and sodium monofluorophosphate.   Fluoride not only decreases the amount of enamel-dissolving acid produced by plaque bacteria, but aids in the tooth rebuilding process, insinuating itself into the enamel to form an even harder surface which resists future attack.   And the list of medical applications doesn't stop there.   Being put to sleep is a little bit less worrisome thanks to fluorinated anaesthetics such as isoflurane and desflurane, which replaced flammable and explosive alternatives such as diethyl ether and chloroform.   Fluorocarbons are also one of the leading candidates in development as artificial blood, as oxygen is more soluble in these materials than most other solvents.   And radioactive fluorine (18F rather than the naturally-occurring 19F) is a key ingredient in positron emission tomography (or PET), a whole-body imaging technique that allows cancerous tumours to be discovered before they spread.  

 

Fluorochemicals are also a mainstay of industry.   One of the most famous is the polymer polytetrafluoroethylene, better known as Teflon, which holds the title of world's most slippery solid.   Highly thermostable and water proof, it's used as a coating for pots and pans, in baking sprays, and to repel stains on furniture and carpets.   Heating and stretching transforms Teflon into Gore-tex, the porous membrane of sportswear fame.   Gore-tex's pores are small enough to keep water droplets out, while allowing water vapour (that is, sweat) to escape.    So you can run on a rainy day, and still stay dry.   Fluorine plays another important role in keeping you cool, as air-conditioning and household refrigeration units run on energy-efficient fluorocarbon fluids.   And fluorine's uses are not limited to earth.   When astronauts jet off into space they put their trust in fluoroelastomers, a type of fluorinated rubber.   Fashioned into O-rings and other sealing devices, these materials ensure that aircraft remain leak-free even under extreme conditions of heat and cold.   And when accidents do happen, space travellers can rely on fluorocarbon-based fire extinguishers to put the flames out.  

Fluorine has long been known as the 'tiger of chemistry'.   And while the element certainly retains its wild side, we can reasonably claim to have tamed it.   As only a handful of naturally-occurring organofluorine compounds have ever been discovered, some might argue that we now make better use of fluorine than even Nature herself.

Chris Smith

So Teflon is acknowledged as the world's most slippery thing and I bet there are one or two politicians knocking around who are thanking fluorine for that.   Thank you also to Kira Weismann from Zaarland University in Germany.   Next week.ouch

Steve Mylon

I cannot imagine that this is all someone would be saying if they were unfortunate enough to be stricken with the disease of the same name.   The ouch-ouch disease.

The disease results from excessive cadmium poisoning and was first reported in a small town about 200 miles north west of Tokyo.   Rice grown in cadmium contaminated soils had more than 10 times the cadmium content than normal rice.   The ouch-ouch-ness of this disease resulted from weak and brittle bones subject to collapse due to high porosity. 

 

Chris Smith

And you can find out about the ouch-ouch factor with Steve Mylon when he uncovers the story of Cadmium on next week's Chemistry in Its Element.   I'm Chris Smith, thank you for listening and goodbye.

(Promo)

 

Chemistry in its elementis brought to you by the Royal Society of Chemistry and produced by thenakedscientists dot com. There's more information and other episodes of Chemistry in its element on our website at chemistryworld dot org forward slash elements. 

 

(End promo)

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Resources

Description :
The Group 7 elements are called the halogens. This experiment involves some reactions of the halogens.
Description :
How does reactivity change upon descending the group?
Description :
Studying the physical characteristics of the group 7 non-metals known as the halogens
Description :
Each of the halogens forms a monovalent (singly-charged) anion. In this experiment you will be looking at the similarities and differences in some of the properties of these halide ions.
Description :
Demonstrating how the more reactive fluorine displaces the less reactive halogens
Description :
The halogens are elements of Group 7 of the Periodic table. This experiment illustrates some of the trends and similarities within the compounds of this group.
 

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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.
Additional information for platinum, gold, neodymium and dysprosium obtained from Material Value Consultancy Ltd www.matvalue.com
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.