Periodic Table > Strontium


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

For more information on Murray Robertson’s image see Uses and properties facts below.


Fact box terminology

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.

Elements are laid out into rows or ‘periods’ so that similar chemical behaviour is observed in columns.

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.

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.

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 Melting point 777 oC, 1430.6 oF, 1050.15 K 
Period Boiling point 1377 oC, 2510.6 oF, 1650.15 K 
Block Density (kg m-3) 2583 
Atomic number 38  Relative atomic mass 87.62  
State at room temperature Solid  Key isotopes 86Sr, 87Sr, 88Sr 
Electron configuration [Kr] 5s2  CAS number 7440-24-6 
ChemSpider ID 4514263 ChemSpider is a free chemical structure database

Uses and properties 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.


The description of the element in its natural form.

Uses and properties

Image explanation
The image is of a highly abstracted metallic ‘mushroom cloud’. It alludes to the presence of strontium in nuclear fallout.
A soft, silvery metal that burns in air and reacts with water.
Strontium is best known for the brilliant reds its salts give to fireworks and flares. It is also used in producing ferrite magnets and refining zinc.

Modern ‘glow-in-the-dark’ paints and plastics contain strontium aluminate. They absorb light during the day and release it slowly for hours afterwards.

Strontium-90, a radioactive isotope, is a by-product of nuclear reactors and present in nuclear fallout. It has a half-life of 28 years. It is absorbed by bone tissue instead of calcium and can destroy bone marrow and cause cancer. However, it is also useful as it is one of the best high-energy beta-emitters known. It can be used to generate electricity for space vehicles, remote weather stations and navigation buoys. It can also be used for thickness gauges and to remove static charges from machinery handling paper or plastic.

Strontium chloride hexahydrate is an ingredient in toothpaste for sensitive teeth.
Biological role
Strontium is incorporated into the shells of some deep-sea creatures and is essential to some stony corals. It has no biological role in humans and is non-toxic. Because it is similar to calcium, it can mimic its way into our bodies, ending up in our bones.

Radioactive strontium-90, which is produced in nuclear explosions and released during nuclear plant accidents, is particularly dangerous because it can be absorbed into the bones of young children.
Natural abundance
Strontium is found mainly in the minerals celestite and strontianite. China is now the leading producer of strontium. Strontium metal can be prepared by electrolysis of the molten strontium chloride and potassium chloride, or by reducing strontium oxide with aluminium in a vacuum.
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) 2.490 Covalent radius (Å) 1.9
Electron affinity (kJ mol-1) 4.63 Electronegativity
(Pauling scale)
Ionisation energies
(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.


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 7.5
Country with largest reserve base China
Crustal abundance (ppm) 320
Leading producer China
Reserve base distribution (%) 91.70
Production concentration (%) 87.00
Total governance factor(production) 8
Top 3 countries (mined)
  • 1) China
  • 2) USA
Top 3 countries (production)
  • 1) China
  • 2) Spain
  • 3) Mexico

Oxidation states and 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


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.

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 and isotopes

Common oxidation states 2
Isotopes Isotope Atomic mass Natural abundance (%) Half life Mode of decay
  84Sr 83.913 0.56
  86Sr 85.909 9.86
  87Sr 86.909 7
  88Sr 87.906 82.58

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 and temperature data – advanced

Molar heat capacity
(J mol-1 K-1)
26.79 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)
x 10-11
x 10-4
1.13 121 - - - - - - -
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In 1787, an unusual rock which had been found in a lead mine at Strontian, Scotland, was investigated by Adair Crawford, an Edinburgh doctor. He realised it was a new mineral containing an unknown ‘earth’ which he named strontia. In 1791, another Edinburgh man, Thomas Charles Hope, made a fuller investigation of it and proved it was a new element. He also noted that it caused the flame of a candle to burn red.

Meanwhile Martin Heinrich Klaproth in Germany was working with the same mineral and he produced both strontium oxide and strontium hydroxide.

Strontium metal itself was isolated in 1808 at the Royal Institution in London by Humphry Davy by means of electrolysis, using the method with which he had already isolated sodium and potassium.

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Listen to Strontium Podcast
Transcript :

Chemistry in Its Element - Strontium



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, vegetarian gladiators, red fireworks and a mineral mistaken for Barium; they are all under Strontium's spotlight. Here's Richard Van Noorden.


Richard Van Noorden

In 1787, an intriguing mineral came to Edinburgh from a Lead mine in a small village on the shores of Loch Sunart, Argyll, in the western highlands of Scotland. At that time, the stuff was thought to be some sort of Barium compound. It was three year's later that Scott's Irish chemist, Adair Crawford, published a paper claiming that the mineral held a new species including a new chemical element. Other chemists, such as Edinburgh's Thomas Hope later prepared a number of compounds with the element, noting that it caused the candle's flame to burn red, while Barium compounds gave a green colour. And in 1808, Humphry Davy in London isolated the soft, silvery metal of the new element using electrolysis. The Scottish village was called Strontian, the mineral found there, strontianite and the new element Strontium. So, it seems there never was an eminent professor, Stront, commemorated by element number 38. 


Today, whenever you see a firework light up in brilliant crimson or a red flare smoking its way around a football stadium, you're looking at the light emitted from electrons transiting between energy levels in nitrate or carbonate salts as Strontium. Strontium is most famous for that red glow in a flame, but as a metal it behaves like its reactive group II neighbours, Beryllium, Magnesium, Calcium and Barium. It's soft and silvery when freshly cut, but this sheen quickly turns yellow when exposed to air, as the metal readily reacts to form oxides; unlike other reactive alkaline earth metals, natural Strontium is always found locked away in mineral compounds. Apart from the previously mentioned strontianite, which we know as Strontium carbonate, there is also the beautiful sky blue celestite, Strontium sulphate, which was discovered in Gloucestershire in 1799, where the locals were using it as gravel for paths in ornamental gardens.


Apart from colouring fireworks, we don't have much call nowadays for Strontium compounds. Strontium carbonate notably is found in cathode ray tubes in old television sets. One of Strontium's isotopes Strontium-90 has a more sinister reputation. It's a radioactive beta emitter, produced by nuclear fission with a half-life of 29 years. Created by nuclear tests from 1945 to the early 1970s, Strontium-90 made its way from the air to grassland, cow stomachs, dairy products and as 1950's studies showed into children's milk teeth. It collects in bones too, being of a similar size to its group II neighbour, Calcium ions. The nuclear reactor accident at Chernobyl in 1986 also threw Strontium-90 into the air. Nowadays, it's used as a radioactive tracer in cancer therapy. Still Strontium's close relation to Calcium has made it a modern treatment for treating osteoporosis as the salt Strontium ranelate, using non-radioactive isotopes, of course. Because Strontium ions are roughly the same size as Calcium ions, they bind tightly to Calcium sensing receptors. It seems that this stimulates the formation of new bones and prevents old bone from being broken down.  


And tracing Strontium isotope levels in bone has allowed analytical chemists to come up with all sorts of conclusions about our past ancestor's diets, knowing that plants tend to be higher in natural Strontium than meat. In 2007, for instance, Austrian researchers hit headlines by comparing Strontium and Zinc levels to support the hypothesis that Roman gladiators were vegetarians who ate mainly barley, beans and dried fruits.


Chris Smith

Chemistry World's Richard Van Noorden wrestling gladiator style with the story of Strontium. Next time, we've heard of running through treacle, but what about this proposition.


Fred Campbell

Could a man walk across a swimming pool filled with Mercury? Don't ask me how the conversation had reached this point, but being surrounded by friends, who would, it is fair to say, describe themselves as science illiterate, I knew it was up to me, the token scientist around the table, to give the definitive answer. "No." I confidently said, adding rather smugly, "it is nowhere near dense enough." The next morning I was rudely awakened by my ringing mobile; not for the first time, I was wrong!


Chris Smith

And you can find out exactly how wrong Fred Campbell was at his dinner party when he unlocks the chemical secrets of quick silver, otherwise known as Mercury on next week's Chemistry in its element. I hope you can join us. I'm Chris Smith, thanks for listening.   Goodbye!




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 web site at chemistryworld dot org forward slash elements.


(End promo)

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Description :
In this experiment you will be observing and interpreting the changes when drops of solutions of various anions are added to drops of solutions of Group 2 element cations.
Description :
A series of short experiments and demonstrations about the chemistry of light, taken from a lecture by Peter Wothers from the University of Cambridge
Description :
In this experiment the pH of various oxides is tested.
Description :
Assessment for Learning is an effective way of actively involving students in their learning.  Each session plan comes with suggestions about how to organise activities and worksheets that may be use...
Description :
Metals in Group 2 of the Periodic Table are less reactive than those in Group 1. This experiment indicates the relative reactivity of elements within the group.
Description :
In this experiment you will be looking to see whether precipitates form when you add drops of solutions of sulphates or carbonates to drops of solutions of Group 1 or 2 metal ions.

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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
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.