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For more information on the Visual Elements image see the Uses and properties section below. < Move to Rubidium Move to Yttrium > Strontium  Discovery date1790 Discovered byAdair Crawford Origin of the nameStrontium is named after Strontian, a small town in Scotland. Allotropes Sr Strontium 38 87.62
Glossary Group Period Block Atomic number Electron configuration Melting point Boiling point Sublimation Density (g cm−3) Relative atomic mass Isotopes CAS number Fact boxFact boxGroup2 Melting point777°C, 1431°F, 1050 K Period5 Boiling point1377°C, 2511°F, 1650 K Blocks Density (g cm−3)2.64 Atomic number38 Relative atomic mass87.62 State at 20°CSolid Key isotopes86Sr, 87Sr, 88Sr Electron configuration[Kr] 5s2 CAS number7440-24-6 ChemSpider ID4514263ChemSpider 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 propertiesUses and propertiesImage explanation The image is of a highly abstracted metallic ‘mushroom cloud’. It alludes to the presence of strontium in nuclear fallout. Appearance A soft, silvery metal that burns in air and reacts with water. Uses 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. Help text not available for this section currently HistoryHistoryElements and Periodic Table History 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.
Glossary Atomic radius, non-bonded Covalent radius Electron affinity Electronegativity (Pauling scale) First ionisation energy Atomic dataAtomic dataAtomic radius, non-bonded (Å)2.49Covalent radius (Å)1.90Electron affinity (kJ mol−1)4.631Electronegativity 1st 549.47 2nd 1064.243 3rd 4138.26 4th 5500 5th 6908.4 6th 8760.9 7th 10227 8th 11800.2
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 yyears ddays hhours mminutes ssecondsMode of decay αalpha particle emission βnegative beta (electron) emission β+positron emission ECorbital electron capture sfspontaneous fission ββdouble beta emission ECECdouble orbital electron capture Oxidation states and isotopesOxidation states and isotopesCommon oxidation states2IsotopesIsotopeAtomic massNatural abundance (%)Half lifeMode of decay 84Sr83.9130.56- - 86Sr85.9099.86- - 87Sr86.9097- - 88Sr87.90682.58- -
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. 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 riskSupply riskRelative supply risk8.6Crustal abundance (ppm)320Recycling rate (%)<10SubstitutabilityUnknownProduction concentration (%)83Reserve distribution (%)100Top 3 producers
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 – advancedPressure and temperature data – advancedSpecific heat capacity Help text not available for this section currently PodcastsPodcastsListen to Strontium Podcast Transcript : Chemistry in its element: strontium(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, 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! (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) Help text not available for this section currently VideoVideoClick here to view videos about Strontium View videos about Help Text ResourcesResourcesLearn Chemistry: Your single route to hundreds of free-to-access chemistry teaching resources.
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How many electrons does strontium have?2,8,18,8,2Strontium / Electrons per shellnull
Which element has 6 unpaired electrons?Cr has the 6 unpaired electrons in its ground state.
How many unpaired electrons does SN have?Thus the no. of unpaired electrons in the ground state of Sn is 2.
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How many unpaired electrons does strontium have
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