Strontium

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Strontium, 38Sr
Strontium destilled crystals.jpg
Strontium
Pronunciation
Appearancesilvery white metallic; with a pale yellow tint [1]
Standard atomic weight Ar°(Sr)
Strontium in the periodic table
Hydrogen Helium
Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon
Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon
Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton
Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine Xenon
Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury (element) Thallium Lead Bismuth Polonium Astatine Radon
Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson
Ca
↑
Sr
↓
Ba
rubidium ← strontium → yttrium
Atomic number (Z)38
Group group 2 (alkaline earth metals)
Period period 5
Block   s-block
Electron configuration [ Kr ] 5s2
Electrons per shell2, 8, 18, 8, 2 [4]
Physical properties
Phase at  STP solid
Melting point 1050  K ​(777 °C,​1431 °F)
Boiling point 1650 K​(1377 °C,​2511 °F)
Density (near r.t.)2.64 g/cm3
when liquid (at m.p.)2.375 g/cm3
Heat of fusion 7.43  kJ/mol
Heat of vaporization 141 kJ/mol
Molar heat capacity 26.4 J/(mol·K)
Vapor pressure
P (Pa)1101001 k10 k100 k
at T (K)796882990113913451646
Atomic properties
Oxidation states +1, [5] +2 (a strongly basic oxide)
Electronegativity Pauling scale: 0.95
Ionization energies
  • 1st: 549.5 kJ/mol
  • 2nd: 1064.2 kJ/mol
  • 3rd: 4138 kJ/mol
Atomic radius empirical:215  pm
Covalent radius 195±10 pm
Van der Waals radius 249 pm
Strontium spectrum visible.png
Spectral lines of strontium
Other properties
Natural occurrence primordial
Crystal structure ​ face-centered cubic (fcc)
Cubic-face-centered.svg
Thermal expansion 22.5 µm/(m⋅K)(at 25 °C)
Thermal conductivity 35.4 W/(m⋅K)
Electrical resistivity 132 nΩ⋅m(at 20 °C)
Magnetic ordering paramagnetic
Molar magnetic susceptibility −92.0×10−6 cm3/mol(298 K) [6]
Young's modulus 15.7 GPa
Shear modulus 6.03 GPa
Poisson ratio 0.28
Mohs hardness 1.5
CAS Number 7440-24-6
History
Namingafter the mineral strontianite, itself named after Strontian, Scotland
Discovery William Cruickshank (1787)
First isolation Humphry Davy (1808)
Isotopes of strontium
Main isotopes [7] Decay
abun­dance half-life (t1/2) mode pro­duct
82Sr synth 25.36 d ε 82Rb
83Srsynth1.35 dε 83Rb
β+ 83Rb
γ –
84Sr0.56% stable
85Srsynth64.84 dε 85Rb
γ–
86Sr9.86%stable
87Sr7%stable
88Sr82.6%stable
89Srsynth50.52 d β− 89Y
90Sr trace 28.90 yβ− 90Y
Symbol category class.svg  Category: Strontium
| references

Strontium is a chemical element; it has symbol Sr and atomic number 38. An alkaline earth metal, strontium is a soft silver-white yellowish metallic element that is highly chemically reactive. The metal forms a dark oxide layer when it is exposed to air. Strontium has physical and chemical properties similar to those of its two vertical neighbors in the periodic table, calcium and barium. It occurs naturally mainly in the minerals celestine and strontianite, and is mostly mined from these.

Contents

Both strontium and strontianite are named after Strontian, a village in Scotland near which the mineral was discovered in 1790 by Adair Crawford and William Cruickshank; it was identified as a new element the next year from its crimson-red flame test color. Strontium was first isolated as a metal in 1808 by Humphry Davy using the then newly discovered process of electrolysis. During the 19th century, strontium was mostly used in the production of sugar from sugar beets (see strontian process). At the peak of production of television cathode-ray tubes, as much as 75% of strontium consumption in the United States was used for the faceplate glass. [8] With the replacement of cathode-ray tubes with other display methods, consumption of strontium has dramatically declined. [8]

While natural strontium (which is mostly the isotope strontium-88) is stable, the synthetic strontium-90 is radioactive and is one of the most dangerous components of nuclear fallout, as strontium is absorbed by the body in a similar manner to calcium. Natural stable strontium, on the other hand, is not hazardous to health.

Characteristics

Oxidized dendritic strontium Strontium 1.jpg
Oxidized dendritic strontium

Strontium is a divalent silvery metal with a pale yellow tint whose properties are mostly intermediate between and similar to those of its group neighbors calcium and barium. [9] It is softer than calcium and harder than barium. Its melting (777 °C) and boiling (1377 °C) points are lower than those of calcium (842 °C and 1484 °C respectively); barium continues this downward trend in the melting point (727 °C), but not in the boiling point (1900 °C). The density of strontium (2.64 g/cm3) is similarly intermediate between those of calcium (1.54 g/cm3) and barium (3.594 g/cm3). [10] Three allotropes of metallic strontium exist, with transition points at 235 and 540 °C.[ citation needed ]

The standard electrode potential for the Sr2+/Sr couple is −2.89 V, approximately midway between those of the Ca2+/Ca (−2.84 V) and Ba2+/Ba (−2.92 V) couples, and close to those of the neighboring alkali metals. [11] Strontium is intermediate between calcium and barium in its reactivity toward water, with which it reacts on contact to produce strontium hydroxide and hydrogen gas. Strontium metal burns in air to produce both strontium oxide and strontium nitride, but since it does not react with nitrogen below 380 °C, at room temperature it forms only the oxide spontaneously. [10] Besides the simple oxide SrO, the peroxide SrO2 can be made by direct oxidation of strontium metal under a high pressure of oxygen, and there is some evidence for a yellow superoxide Sr(O2)2. [12] Strontium hydroxide, Sr(OH)2, is a strong base, though it is not as strong as the hydroxides of barium or the alkali metals. [13] All four dihalides of strontium are known. [14]

Due to the large size of the heavy s-block elements, including strontium, a vast range of coordination numbers is known, from 2, 3, or 4 all the way to 22 or 24 in SrCd11 and SrZn13. The Sr2+ ion is quite large, so that high coordination numbers are the rule. [15] The large size of strontium and barium plays a significant part in stabilising strontium complexes with polydentate macrocyclic ligands such as crown ethers: for example, while 18-crown-6 forms relatively weak complexes with calcium and the alkali metals, its strontium and barium complexes are much stronger. [16]

Organostrontium compounds contain one or more strontium–carbon bonds. They have been reported as intermediates in Barbier-type reactions. [17] [18] [19] Although strontium is in the same group as magnesium, and organomagnesium compounds are very commonly used throughout chemistry, organostrontium compounds are not similarly widespread because they are more difficult to make and more reactive. Organostrontium compounds tend to be more similar to organoeuropium or organosamarium compounds due to the similar ionic radii of these elements (Sr2+ 118 pm; Eu2+ 117 pm; Sm2+ 122 pm). Most of these compounds can only be prepared at low temperatures; bulky ligands tend to favor stability. For example, strontium dicyclopentadienyl, Sr(C5H5)2, must be made by directly reacting strontium metal with mercurocene or cyclopentadiene itself; replacing the C5H5 ligand with the bulkier C5(CH3)5 ligand on the other hand increases the compound's solubility, volatility, and kinetic stability. [20]

Because of its extreme reactivity with oxygen and water, strontium occurs naturally only in compounds with other elements, such as in the minerals strontianite and celestine. It is kept under a liquid hydrocarbon such as mineral oil or kerosene to prevent oxidation; freshly exposed strontium metal rapidly turns a yellowish color with the formation of the oxide. Finely powdered strontium metal is pyrophoric, meaning that it will ignite spontaneously in air at room temperature. Volatile strontium salts impart a bright red color to flames, and these salts are used in pyrotechnics and in the production of flares. [10] Like calcium and barium, as well as the alkali metals and the divalent lanthanides europium and ytterbium, strontium metal dissolves directly in liquid ammonia to give a dark blue solution of solvated electrons. [9]

Isotopes

Natural strontium is a mixture of four stable isotopes: 84Sr, 86Sr, 87Sr, and 88Sr. [10] On these isotopes, 88Sr is the most abundant, makes up about 82.6% of all natural strontium, though the abundance varies due to the production of radiogenic 87Sr as the daughter of long-lived beta-decaying 87 Rb. [21] This is the basis of rubidium–strontium dating. Of the unstable isotopes, the primary decay mode of the isotopes lighter than 85Sr is electron capture or positron emission to isotopes of rubidium, and that of the isotopes heavier than 88Sr is electron emission to isotopes of yttrium. Of special note are 89Sr and 90Sr. The former has a half-life of 50.6 days and is used to treat bone cancer due to strontium's chemical similarity and hence ability to replace calcium. [22] [23] While 90Sr (half-life 28.90 years) has been used similarly, it is also an isotope of concern in fallout from nuclear weapons and nuclear accidents due to its production as a fission product. Its presence in bones can cause bone cancer, cancer of nearby tissues, and leukemia. [24] The 1986 Chernobyl nuclear accident contaminated about 30,000 km2 with greater than 10 kBq/m2 with 90Sr, which accounts for about 5% of the 90Sr which was in the reactor core. [25]

History

Flame test for strontium FlammenfarbungSr.png
Flame test for strontium

Strontium is named after the Scottish village of Strontian (Scottish Gaelic : Sròn an t-Sìthein), where it was discovered in the ores of the lead mines. [26]

In 1790, Adair Crawford, a physician engaged in the preparation of barium, and his colleague William Cruickshank, recognised that the Strontian ores exhibited properties that differed from those in other "heavy spars" sources. [27] This allowed Crawford to conclude on page 355 "... it is probable indeed, that the scotch mineral is a new species of earth which has not hitherto been sufficiently examined." The physician and mineral collector Friedrich Gabriel Sulzer analysed together with Johann Friedrich Blumenbach the mineral from Strontian and named it strontianite. He also came to the conclusion that it was distinct from the witherite and contained a new earth (neue Grunderde). [28] In 1793 Thomas Charles Hope, a professor of chemistry at the University of Glasgow studied the mineral [29] [30] and proposed the name strontites. [31] [32] [33] He confirmed the earlier work of Crawford and recounted: "... Considering it a peculiar earth I thought it necessary to give it an name. I have called it Strontites, from the place it was found; a mode of derivation in my opinion, fully as proper as any quality it may possess, which is the present fashion." The element was eventually isolated by Sir Humphry Davy in 1808 by the electrolysis of a mixture containing strontium chloride and mercuric oxide, and announced by him in a lecture to the Royal Society on 30 June 1808. [34] In keeping with the naming of the other alkaline earths, he changed the name to strontium. [35] [36] [37] [38] [39]

The first large-scale application of strontium was in the production of sugar from sugar beet. Although a crystallisation process using strontium hydroxide was patented by Augustin-Pierre Dubrunfaut in 1849 [40] the large scale introduction came with the improvement of the process in the early 1870s. The German sugar industry used the process well into the 20th century. Before World War I the beet sugar industry used 100,000 to 150,000 tons of strontium hydroxide for this process per year. [41] The strontium hydroxide was recycled in the process, but the demand to substitute losses during production was high enough to create a significant demand initiating mining of strontianite in the Münsterland. The mining of strontianite in Germany ended when mining of the celestine deposits in Gloucestershire started. [42] These mines supplied most of the world strontium supply from 1884 to 1941. Although the celestine deposits in the Granada basin were known for some time the large scale mining did not start before the 1950s. [43]

During atmospheric nuclear weapons testing, it was observed that strontium-90 is one of the nuclear fission products with a relatively high yield. The similarity to calcium and the chance that the strontium-90 might become enriched in bones made research on the metabolism of strontium an important topic. [44] [45]

Occurrence

The mineral celestine (SrSO4) Celestine Poland.jpg
The mineral celestine (SrSO4)

Strontium commonly occurs in nature, being the 15th most abundant element on Earth (its heavier congener barium being the 14th), estimated to average approximately 360  parts per million in the Earth's crust [46] and is found chiefly as the sulfate mineral celestine (SrSO4) and the carbonate strontianite (SrCO3). Of the two, celestine occurs much more frequently in deposits of sufficient size for mining. Because strontium is used most often in the carbonate form, strontianite would be the more useful of the two common minerals, but few deposits have been discovered that are suitable for development. [47] Because of the way it reacts with air and water, strontium only exists in nature when combined to form minerals. Naturally occurring strontium is stable, but its synthetic isotope Sr-90 is only produced by nuclear fallout.

In groundwater strontium behaves chemically much like calcium. At intermediate to acidic pH Sr2+ is the dominant strontium species. In the presence of calcium ions, strontium commonly forms coprecipitates with calcium minerals such as calcite and anhydrite at an increased pH. At intermediate to acidic pH, dissolved strontium is bound to soil particles by cation exchange. [48]

The mean strontium content of ocean water is 8 mg/L. [49] [50] At a concentration between 82 and 90 μmol/L of strontium, the concentration is considerably lower than the calcium concentration, which is normally between 9.6 and 11.6 mmol/L. [51] [52] It is nevertheless much higher than that of barium, 13 μg/L. [10]

Production

Strontium producers in 2014 World Strontium Production 2014.svg
Strontium producers in 2014

The three major producers of strontium as celestine as of 2015 are China (150,000  t), Spain (90,000 t), and Mexico (70,000 t); Argentina (10,000 t) and Morocco (2,500 t) are smaller producers. Although strontium deposits occur widely in the United States, they have not been mined since 1959. [53]

A large proportion of mined celestine (SrSO4) is converted to the carbonate by two processes. Either the celestine is directly leached with sodium carbonate solution or the celestine is roasted with coal to form the sulfide. The second stage produces a dark-coloured material containing mostly strontium sulfide. This so-called "black ash" is dissolved in water and filtered. Strontium carbonate is precipitated from the strontium sulfide solution by introduction of carbon dioxide. [54] The sulfate is reduced to the sulfide by the carbothermic reduction:

SrSO4 + 2 C → SrS + 2 CO2

About 300,000 tons are processed in this way annually. [55]

The metal is produced commercially by reducing strontium oxide with aluminium. The strontium is distilled from the mixture. [55] Strontium metal can also be prepared on a small scale by electrolysis of a solution of strontium chloride in molten potassium chloride: [11]

Sr2+ + 2
e−
 → Sr
2 Cl− → Cl2 + 2
e−

Applications

Most of the world's production of strontium used to be consumed in the production of cathode-ray tube (CRT) displays. The glass contained strontium and barium oxide to block X-rays. Monitor.arp.jpg
Most of the world's production of strontium used to be consumed in the production of cathode-ray tube (CRT) displays. The glass contained strontium and barium oxide to block X-rays.

Consuming 75% of production, the primary use for strontium was in glass for colour television cathode-ray tubes, [55] where it prevented X-ray emission. [56] [57] This application for strontium has been declining because CRTs are being replaced by other display methods. This decline has a significant influence on the mining and refining of strontium. [47] All parts of the CRT must absorb X-rays. In the neck and the funnel of the tube, lead glass is used for this purpose, but this type of glass shows a browning effect due to the interaction of the X-rays with the glass. Therefore, the front panel is made from a different glass mixture with strontium and barium to absorb the X-rays. The average values for the glass mixture determined for a recycling study in 2005 is 8.5% strontium oxide and 10% barium oxide. [58]

Because strontium is so similar to calcium, it is incorporated in the bone. All four stable isotopes are incorporated, in roughly the same proportions they are found in nature. However, the actual distribution of the isotopes tends to vary greatly from one geographical location to another. Thus, analyzing the bone of an individual can help determine the region it came from. [59] [60] This approach helps to identify the ancient migration patterns and the origin of commingled human remains in battlefield burial sites. [61]

87Sr/86Sr ratios are commonly used to determine the likely provenance areas of sediment in natural systems, especially in marine and fluvial environments. Dasch (1969) showed that surface sediments of Atlantic displayed 87Sr/86Sr ratios that could be regarded as bulk averages of the 87Sr/86Sr ratios of geological terrains from adjacent landmasses. [62] A good example of a fluvial-marine system to which Sr isotope provenance studies have been successfully employed is the River Nile-Mediterranean system. [63] Due to the differing ages of the rocks that constitute the majority of the Blue and White Nile, catchment areas of the changing provenance of sediment reaching the River Nile Delta and East Mediterranean Sea can be discerned through strontium isotopic studies. Such changes are climatically controlled in the Late Quaternary. [63]

More recently, 87Sr/86Sr ratios have also been used to determine the source of ancient archaeological materials such as timbers and corn in Chaco Canyon, New Mexico. [64] [65] 87Sr/86Sr ratios in teeth may also be used to track animal migrations. [66] [67]

Strontium aluminate is frequently used in glow in the dark toys, as it is chemically and biologically inert. [68]

Strontium salts are added to fireworks in order to create red colors. Ignis Brunensis 2010-05-22 (5).jpg
Strontium salts are added to fireworks in order to create red colors.

Strontium carbonate and other strontium salts are added to fireworks to give a deep red colour. [69] This same effect identifies strontium cations in the flame test. Fireworks consume about 5% of the world's production. [55] Strontium carbonate is used in the manufacturing of hard ferrite magnets. [70] [71]

Strontium chloride is sometimes used in toothpastes for sensitive teeth. One popular brand includes 10% total strontium chloride hexahydrate by weight. [72] Small amounts are used in the refining of zinc to remove small amounts of lead impurities. [10] The metal itself has a limited use as a getter, to remove unwanted gases in vacuums by reacting with them, although barium may also be used for this purpose. [11]

The ultra-narrow optical transition between the [Kr]5s21S0 electronic ground state and the metastable [Kr]5s5p 3P0 excited state of 87Sr is one of the leading candidates for the future re-definition of the second in terms of an optical transition as opposed to the current definition derived from a microwave transition between different hyperfine ground states of 133Cs. [73] Current optical atomic clocks operating on this transition already surpass the precision and accuracy of the current definition of the second. [74]

Radioactive strontium

89Sr is the active ingredient in Metastron, [75] a radiopharmaceutical used for bone pain secondary to metastatic bone cancer. The strontium is processed like calcium by the body, preferentially incorporating it into bone at sites of increased osteogenesis. This localization focuses the radiation exposure on the cancerous lesion. [23]

RTGs from Soviet-era lighthouses Soviet RTG.jpg
RTGs from Soviet-era lighthouses

90Sr has been used as a power source for radioisotope thermoelectric generators (RTGs). 90Sr produces approximately 0.93 watts of heat per gram (it is lower for the form of 90Sr used in RTGs, which is strontium fluoride). [76] However, 90Sr has one third the lifetime and a lower density than 238Pu, another RTG fuel. The main advantage of 90Sr is that it is cheaper than 238Pu and is found in nuclear waste. The Soviet Union deployed nearly 1000 of these RTGs on its northern coast as a power source for lighthouses and meteorology stations. [77] [78]

Biological role

Strontium
Hazards
GHS labelling:
GHS-pictogram-flamme.svg GHS-pictogram-exclam.svg
Danger
H261, H315
P223, P231+P232, P370+P378, P422 [79]
NFPA 704 (fire diamond)
NFPA 704.svgHealth 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformFlammability 0: Will not burn. E.g. waterInstability 2: Undergoes violent chemical change at elevated temperatures and pressures, reacts violently with water, or may form explosive mixtures with water. E.g. white phosphorusSpecial hazard W: Reacts with water in an unusual or dangerous manner. E.g. sodium, sulfuric acid
2
0
2
W

Acantharea, a relatively large group of marine radiolarian protozoa, produce intricate mineral skeletons composed of strontium sulfate. [80] In biological systems, calcium is substituted to a small extent by strontium. [81] In the human body, most of the absorbed strontium is deposited in the bones. The ratio of strontium to calcium in human bones is between 1:1000 and 1:2000, roughly in the same range as in the blood serum. [82]

Effect on the human body

The human body absorbs strontium as if it were its lighter congener calcium. Because the elements are chemically very similar, stable strontium isotopes do not pose a significant health threat. The average human has an intake of about two milligrams of strontium a day. [83] In adults, strontium consumed tends to attach only to the surface of bones, but in children, strontium can replace calcium in the mineral of the growing bones and thus lead to bone growth problems. [84]

The biological half-life of strontium in humans has variously been reported as from 14 to 600 days, [85] [86] 1,000 days, [87] 18 years, [88] 30 years [89] and, at an upper limit, 49 years. [90] The wide-ranging published biological half-life figures are explained by strontium's complex metabolism within the body. However, by averaging all excretion paths, the overall biological half-life is estimated to be about 18 years. [91] The elimination rate of strontium is strongly affected by age and sex, due to differences in bone metabolism. [92]

The drug strontium ranelate aids bone growth, increases bone density, and lessens the incidence of vertebral, peripheral, and hip fractures. [93] [94] However, strontium ranelate also increases the risk of venous thromboembolism, pulmonary embolism, and serious cardiovascular disorders, including myocardial infarction. Its use is therefore now restricted. [95] Its beneficial effects are also questionable, since the increased bone density is partially caused by the increased density of strontium over the calcium which it replaces. Strontium also bioaccumulates in the body. [96] Despite restrictions on strontium ranelate, strontium is still contained in some supplements. [97] [98] There is not much scientific evidence on risks of strontium chloride when taken by mouth. Those with a personal or family history of blood clotting disorders are advised to avoid strontium. [97] [98]

Strontium has been shown to inhibit sensory irritation when applied topically to the skin. [99] [100] Topically applied, strontium has been shown to accelerate the recovery rate of the epidermal permeability barrier (skin barrier). [101]

Nuclear waste

Strontium-90 is a radioactive fission product produced by nuclear reactors used in nuclear power. It is a major component of high level radioactivity of nuclear waste and spent nuclear fuel. Its 29-year half life is short enough that its decay heat has been used to power arctic lighthouses, but long enough that it can take hundreds of years to decay to safe levels. Exposure from contaminated water and food may increase the risk of leukemia, bone cancer [102] and primary hyperparathyroidism. [103]

Remediation

Algae has shown selectivity for strontium in studies, where most plants used in bioremediation have not shown selectivity between calcium and strontium, often becoming saturated with calcium, which is greater in quantity and also present in nuclear waste. [102]

Researchers have looked at the bioaccumulation of strontium by Scenedesmus spinosus (algae) in simulated wastewater. The study claims a highly selective biosorption capacity for strontium of S. spinosus, suggesting that it may be appropriate for use in treating nuclear wastewater. [104]

A study of the pond alga Closterium moniliferum using non-radioactive strontium found that varying the ratio of barium to strontium in water improved strontium selectivity. [102]

See also

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The alkaline earth metals are six chemical elements in group 2 of the periodic table. They are beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra). The elements have very similar properties: they are all shiny, silvery-white, somewhat reactive metals at standard temperature and pressure.

<span class="mw-page-title-main">Celestine (mineral)</span> Sulfate mineral

Celestine (the IMA-accepted name) or celestite is a mineral consisting of strontium sulfate (SrSO4). The mineral is named for its occasional delicate blue color. Celestine and the carbonate mineral strontianite are the principal sources of the element strontium, commonly used in fireworks and in various metal alloys.

<span class="mw-page-title-main">Strontianite</span> Rare carbonate mineral and raw material for the extraction of strontium

Strontianite (SrCO3) is an important raw material for the extraction of strontium. It is a rare carbonate mineral and one of only a few strontium minerals. It is a member of the aragonite group.

<span class="mw-page-title-main">Martin Heinrich Klaproth</span> German chemist (1743–1817)

Martin Heinrich Klaproth was a German chemist. He trained and worked for much of his life as an apothecary, moving in later life to the university. His shop became the second-largest apothecary in Berlin, and the most productive artisanal chemical research center in Europe.

The alkaline earth metal strontium (38Sr) has four stable, naturally occurring isotopes: 84Sr (0.56%), 86Sr (9.86%), 87Sr (7.0%) and 88Sr (82.58%). Its standard atomic weight is 87.62(1).

Rubidium (37Rb) has 36 isotopes, with naturally occurring rubidium being composed of just two isotopes; 85Rb (72.2%) and the radioactive 87Rb (27.8%). Normal mixes of rubidium are radioactive enough to fog photographic film in approximately 30 to 60 days.

<span class="mw-page-title-main">Strontium-90</span> Radioactive isotope of strontium

Strontium-90 is a radioactive isotope of strontium produced by nuclear fission, with a half-life of 28.8 years. It undergoes β− decay into yttrium-90, with a decay energy of 0.546 MeV. Strontium-90 has applications in medicine and industry and is an isotope of concern in fallout from nuclear weapons, nuclear weapons testing, and nuclear accidents.

<span class="mw-page-title-main">Strontium carbonate</span> Chemical compound

Strontium carbonate (SrCO3) is the carbonate salt of strontium that has the appearance of a white or grey powder. It occurs in nature as the mineral strontianite.

<span class="mw-page-title-main">Yttrium</span> Chemical element, symbol Y and atomic number 39

Yttrium is a chemical element; it has symbol Y and atomic number 39. It is a silvery-metallic transition metal chemically similar to the lanthanides and has often been classified as a "rare-earth element". Yttrium is almost always found in combination with lanthanide elements in rare-earth minerals and is never found in nature as a free element. 89Y is the only stable isotope and the only isotope found in the Earth's crust.

<span class="mw-page-title-main">Cerium</span> Chemical element, symbol Ce and atomic number 58

Cerium is a chemical element; it has symbol Ce and atomic number 58. Cerium is a soft, ductile, and silvery-white metal that tarnishes when exposed to air. Cerium is the second element in the lanthanide series, and while it often shows the oxidation state of +3 characteristic of the series, it also has a stable +4 state that does not oxidize water. It is also considered one of the rare-earth elements. Cerium has no known biological role in humans but is not particularly toxic, except with intense or continued exposure.

<span class="mw-page-title-main">Ocean island basalt</span> Volcanic rock

Ocean island basalt (OIB) is a volcanic rock, usually basaltic in composition, erupted in oceans away from tectonic plate boundaries. Although ocean island basaltic magma is mainly erupted as basalt lava, the basaltic magma is sometimes modified by igneous differentiation to produce a range of other volcanic rock types, for example, rhyolite in Iceland, and phonolite and trachyte at the intraplate volcano Fernando de Noronha. Unlike mid-ocean ridge basalts (MORBs), which erupt at spreading centers (divergent plate boundaries), and volcanic arc lavas, which erupt at subduction zones (convergent plate boundaries), ocean island basalts are the result of intraplate volcanism. However, some ocean island basalt locations coincide with plate boundaries like Iceland, which sits on top of a mid-ocean ridge, and Samoa, which is located near a subduction zone.

The strontian process is an obsolete chemical method to recover sugar from molasses. Its use in Europe peaked in the middle of the 19th century. The name strontian comes from the Scottish village Strontian where the source mineral strontianite was first found.

<span class="mw-page-title-main">Charles Pecher</span>

Charles Pecher was a Belgian pioneer in nuclear medicine. He discovered and introduced strontium-89 in medical therapeutic procedures in 1939.

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