| Part ofa series on the |
| Periodic table |
|---|
 |
Periodic table forms
|
By periodic table structure |
By other characteristics |
Data pages for elements
|
Aperiod 5 element is one of thechemical elements in the fifth row (orperiod) of theperiodic table of the chemical elements. The periodic table is laid out in rows to illustrate recurring (periodic) trends in the chemical behaviour of the elements as their atomic number increases: a new row is begun when chemical behaviour begins to repeat, meaning that elements with similar behaviour fall into the same vertical columns. The fifth period contains 18 elements, beginning withrubidium and ending withxenon. As a rule, period 5 elements fill their 5sshells first, then their 4d, and 5p shells, in that order; however, there are exceptions, such asrhodium.
This period containstechnetium, one of the two elements untillead that has no stable isotopes (along withpromethium), as well asmolybdenum andiodine, two of the heaviest elements with a known biological role.[1][2]Niobium has the largest known magnetic penetration depth of all the elements.[3]Zirconium is one of the main components ofzircon crystals, currently the oldest known minerals in the Earth's crust. Many latertransition metals, such as rhodium, are very commonly used in jewelry as they are very shiny.[4]
This period is known to have a large number of exceptions to theMadelung rule.
| Chemical element | Block | Electron configuration | ||
|---|---|---|---|---|
| 37 | Rb | Rubidium | s-block | [Kr] 5s1 |
| 38 | Sr | Strontium | s-block | [Kr] 5s2 |
| 39 | Y | Yttrium | d-block | [Kr] 4d1 5s2 |
| 40 | Zr | Zirconium | d-block | [Kr] 4d2 5s2 |
| 41 | Nb | Niobium | d-block | [Kr] 4d4 5s1 (*) |
| 42 | Mo | Molybdenum | d-block | [Kr] 4d5 5s1 (*) |
| 43 | Tc | Technetium | d-block | [Kr] 4d5 5s2 |
| 44 | Ru | Ruthenium | d-block | [Kr] 4d7 5s1 (*) |
| 45 | Rh | Rhodium | d-block | [Kr] 4d8 5s1 (*) |
| 46 | Pd | Palladium | d-block | [Kr] 4d10 (*) |
| 47 | Ag | Silver | d-block | [Kr] 4d10 5s1 (*) |
| 48 | Cd | Cadmium | d-block | [Kr] 4d10 5s2 |
| 49 | In | Indium | p-block | [Kr] 4d10 5s2 5p1 |
| 50 | Sn | Tin | p-block | [Kr] 4d10 5s2 5p2 |
| 51 | Sb | Antimony | p-block | [Kr] 4d10 5s2 5p3 |
| 52 | Te | Tellurium | p-block | [Kr] 4d10 5s2 5p4 |
| 53 | I | Iodine | p-block | [Kr] 4d10 5s2 5p5 |
| 54 | Xe | Xenon | p-block | [Kr] 4d10 5s2 5p6 |
(*) Exception to theMadelung rule
Rubidium is the first element placed in period 5. It is analkali metal, the most reactive group in theperiodic table, having properties and similarities with both other alkali metals and other period 5 elements. For example, rubidium has 5 electron shells, a property found in all other period 5 elements, whereas itselectron configuration's ending is similar to all other alkali metals: s1.[5]Rubidium also follows the trend of increasingreactivity as the atomic number increases in the alkali metals, for it is more reactive thanpotassium, but less so thancaesium. In addition, both potassium and rubidium yield almost the same hue whenignited, so researchers must use different methods to differentiate between these two 1st group elements.[6] Rubidium is very susceptible tooxidation in air, similar to most of the other alkali metals, so it readily transforms intorubidium oxide, a yellow solid with thechemical formula Rb2O.[7]
Strontium is the second element placed in the 5thperiod. It is analkaline earth metal, a relatively reactive group, although not nearly as reactive as thealkali metals. Like rubidium, it has 5electron shells orenergy levels, and in accordance with theMadelung rule it has two electrons in its 5ssubshell.Strontium is a soft metal and is extremelyreactive upon contact with water. If it comes in contact with water, it will combine with theatoms of bothoxygen andhydrogen to formstrontium hydroxide and pure hydrogen gas which quicklydiffuses in theair. In addition, strontium, like rubidium,oxidizes in air and turns ayellow color. When ignited, it will burn with a strong redflame.
Yttrium is achemical element with symbolY andatomic number 39. It is a silvery-metallictransition metal chemically similar to thelanthanides and it has often been classified as a "rare earth element".[8] Yttrium is almost always found combined with the lanthanides inrare earth minerals and is never found in nature as a free element. Its only stableisotope,89Y, is also its only naturally occurring isotope.
In 1787,Carl Axel Arrhenius found a new mineral nearYtterby in Sweden and named itytterbite, after the village.Johan Gadolin discovered yttrium's oxide in Arrhenius' sample in 1789,[9] andAnders Gustaf Ekeberg named the new oxideyttria. Elemental yttrium was first isolated in 1828 byFriedrich Wöhler.[10]
The most important use of yttrium is in makingphosphors, such as the red ones used in television setcathode-ray tube (CRT) displays and inLEDs.[11] Other uses include the production ofelectrodes,electrolytes,electronic filters,lasers andsuperconductors; various medical applications; and astraces in various materials to enhance their properties. Yttrium has no known biological role, and exposure to yttrium compounds can cause lung disease in humans.[12]
Zirconium is achemical element with the symbolZr andatomic number 40. The name of zirconium is taken from the mineralzircon. Its atomic mass is 91.224. It is a lustrous, gray-white, strongtransition metal that resemblestitanium. Zirconium is mainly used as arefractory andopacifier, although minor amounts are used as alloying agent for its strong resistance to corrosion. Zirconium is obtained mainly from the mineralzircon, which is the most important form of zirconium in use.
Zirconium forms a variety ofinorganic andorganometallic compounds such aszirconium dioxide andzirconocene dichloride, respectively. Fiveisotopes occur naturally, three of which are stable. Zirconium compounds have no biological role.
Niobium, orcolumbium, is achemical element with the symbolNb andatomic number 41. It is a soft, grey,ductiletransition metal, which is often found in thepyrochlore mineral, the main commercial source for niobium, andcolumbite. The name comes fromGreek mythology:Niobe, daughter ofTantalus.
Niobium has physical and chemical properties similar to those of the elementtantalum, and the two are therefore difficult to distinguish. The English chemistCharles Hatchett reported a new element similar to tantalum in 1801, and named it columbium. In 1809, the English chemistWilliam Hyde Wollaston wrongly concluded that tantalum and columbium were identical. The German chemistHeinrich Rose determined in 1846 that tantalum ores contain a second element, which he named niobium. In 1864 and 1865, a series of scientific findings clarified that niobium and columbium were the same element (as distinguished from tantalum), and for a century both names were used interchangeably. The name of the element was officially adopted as niobium in 1949.
It was not until the early 20th century that niobium was first used commercially.Brazil is the leading producer of niobium andferroniobium, analloy of niobium and iron. Niobium is used mostly in alloys, the largest part in specialsteel such as that used in gaspipelines. Although alloys contain only a maximum of 0.1%, that small percentage of niobium improves the strength of the steel. The temperature stability of niobium-containingsuperalloys is important for its use injet androcket engines. Niobium is used in varioussuperconducting materials. Thesesuperconducting alloys, also containingtitanium andtin, are widely used in thesuperconducting magnets ofMRI scanners. Other applications of niobium include its use in welding, nuclear industries, electronics, optics,numismatics and jewelry. In the last two applications, niobium's low toxicity and ability to be colored byanodization are particular advantages.
Molybdenum is aGroup 6chemical element with the symbolMo andatomic number 42. The name is from Neo-LatinMolybdaenum, fromAncient GreekΜόλυβδοςmolybdos, meaninglead, itself proposed as aloanword fromAnatolianLuvian andLydian languages,[13] since its ores were confused with lead ores.[14] The free element, which is a silverymetal, has thesixth-highestmelting point of any element. It readily forms hard, stablecarbides, and for this reason it is often used in high-strengthsteel alloys. Molybdenum does not occur as afree metal on Earth, but rather in variousoxidation states in minerals. Industrially, molybdenumcompounds are used inhigh-pressure and high-temperature applications, aspigments andcatalysts.
Molybdenum minerals have long been known, but the element was "discovered" (in the sense of differentiating it as a new entity from the mineral salts of other metals) in 1778 byCarl Wilhelm Scheele. The metal was first isolated in 1781 byPeter Jacob Hjelm.
Most molybdenum compounds have lowsolubility in water, but the molybdate ion MoO42− is soluble and forms when molybdenum-containing minerals are in contact withoxygen and water.
Technetium is thechemical element withatomic number 43 and symbolTc. It is the lowestatomic number element without anystable isotopes; every form of it isradioactive. Nearly all technetium is produced synthetically and only minute amounts are found in nature. Naturally occurring technetium occurs as a spontaneousfission product inuranium ore or byneutron capture inmolybdenum ores. The chemical properties of this silvery gray, crystallinetransition metal are intermediate betweenrhenium andmanganese.
Many of technetium's properties were predicted byDmitri Mendeleev before the element was discovered. Mendeleev noted a gap in hisperiodic table and gave the undiscovered element the provisional nameekamanganese (Em). In 1937 technetium (specifically thetechnetium-97 isotope) became the first predominantly artificial element to be produced, hence its name (from theGreekτεχνητός, meaning "artificial").
Its short-livedgamma ray-emittingnuclear isomer—technetium-99m—is used innuclear medicine for a wide variety of diagnostic tests. Technetium-99 is used as a gamma ray-free source ofbeta particles. Long-livedtechnetium isotopes produced commercially are by-products offission ofuranium-235 innuclear reactors and are extracted fromnuclear fuel rods. Because no isotope of technetium has ahalf-life longer than 4.2 million years (technetium-98), its detection inred giants in 1952, which are billions of years old, helped bolster the theory that stars can produce heavier elements.
Ruthenium is achemical element with symbolRu andatomic number 44. It is a raretransition metal belonging to theplatinum group of theperiodic table. Like the other metals of the platinum group, ruthenium is inert to most chemicals. TheRussian scientistKarl Ernst Claus discovered the element in 1844 and named it afterRuthenia, the Latin word forRus'. Ruthenium usually occurs as a minor component ofplatinum ores and its annual production is only about 12tonnes worldwide. Most ruthenium is used for wear-resistant electrical contacts and the production of thick-film resistors. A minor application of ruthenium is its use in some platinumalloys.
Rhodium is achemical element that is a rare, silvery-white, hard, andchemically inerttransition metal and a member of theplatinum group. It has thechemical symbolRh andatomic number 45. It is composed of only oneisotope,103Rh. Naturally occurring rhodium is found as the free metal, alloyed with similar metals, and never as a chemical compound. It is one of the rarestprecious metals and one of the most costly (gold has since taken over the top spot of cost per ounce).
Rhodium is a so-callednoble metal, resistant to corrosion, found in platinum or nickel ores together with the other members of theplatinum group metals. It wasdiscovered in 1803 byWilliam Hyde Wollaston in one such ore, and named for the rose color of one of its chlorine compounds, produced after it reacted with the powerful acid mixtureaqua regia.
The element's major use (about 80% of world rhodium production) is as one of thecatalysts in thethree-way catalytic converters of automobiles. Because rhodium metal is inert against corrosion and most aggressive chemicals, and because of its rarity, rhodium is usuallyalloyed withplatinum orpalladium and applied in high-temperature and corrosion-resistive coatings.White gold is often plated with a thin rhodium layer to improve its optical impression whilesterling silver is often rhodium plated for tarnish resistance.
Rhodium detectors are used innuclear reactors to measure theneutron flux level.
Palladium is achemical element with thechemical symbolPd and anatomic number of 46. It is a rare and lustrous silvery-white metal discovered in 1803 byWilliam Hyde Wollaston. He named it after theasteroid Pallas, which was itself named after theepithet of theGreek goddessAthena, acquired by her when she slewPallas. Palladium,platinum,rhodium,ruthenium,iridium andosmium form a group of elements referred to as theplatinum group metals (PGMs). These have similar chemical properties, but palladium has the lowest melting point and is the least dense of them.
The unique properties of palladium and other platinum group metals account for their widespread use. A quarter of all goods manufactured today either contain PGMs or have a significant part in their manufacturing process played by PGMs.[15] Over half of the supply of palladium and itscongener platinum goes intocatalytic converters, which convert up to 90% of harmful gases from auto exhaust (hydrocarbons,carbon monoxide, andnitrogen dioxide) into less-harmful substances (nitrogen,carbon dioxide andwater vapor). Palladium is also used in electronics,dentistry,medicine, hydrogen purification, chemical applications, and groundwater treatment. Palladium plays a key role in the technology used forfuel cells, which combine hydrogen and oxygen to produce electricity, heat, and water.
Oredeposits of palladium and other PGMs are rare, and the most extensive deposits have been found in the norite belt of theBushveld Igneous Complex covering theTransvaal Basin in South Africa, theStillwater Complex inMontana, United States, theThunder Bay District ofOntario, Canada, and theNorilsk Complex in Russia.Recycling is also a source of palladium, mostly from scrapped catalytic converters. The numerous applications and limited supply sources of palladium result in the metal attracting considerableinvestment interest.
Silver is a metallicchemical element with thechemical symbolAg (Latin:argentum, from theIndo-European root*arg- for "grey" or "shining") andatomic number 47. A soft, white, lustroustransition metal, it has the highestelectrical conductivity of any element and the highestthermal conductivity of any metal. The metal occurs naturally in its pure, free form (native silver), as analloy withgold and other metals, and in minerals such asargentite andchlorargyrite. Most silver is produced as a byproduct ofcopper,gold,lead, andzincrefining.
Silver has long been valued as aprecious metal, and it is used to make ornaments,jewelry, high-value tableware, utensils (hence the termsilverware), and currencycoins. Today, silver metal is also used in electrical contacts andconductors, in mirrors and incatalysis of chemical reactions. Its compounds are used inphotographic film, and dilutesilver nitrate solutions and other silver compounds are used asdisinfectants and microbiocides. While many medicalantimicrobial uses of silver have been supplanted byantibiotics, further research into clinical potential continues.
Cadmium is achemical element with the symbolCd andatomic number 48. This soft, bluish-white metal is chemically similar to the two other stable metals ingroup 12,zinc andmercury. Like zinc, it prefersoxidation state +2 in most of its compounds and like mercury it shows a low melting point compared totransition metals. Cadmium and itscongeners are not always considered transition metals, in that they do not have partly filled d or f electron shells in the elemental or common oxidation states. The average concentration of cadmium in the Earth's crust is between 0.1 and 0.5 parts per million (ppm). It was discovered in 1817 simultaneously byStromeyer andHermann, both in Germany, as an impurity inzinc carbonate.
Cadmium occurs as a minor component in most zinc ores and therefore is a byproduct of zinc production. It was used for a long time as apigment and for corrosion resistant plating onsteel while cadmium compounds were used to stabilizeplastic. With the exception of its use innickel–cadmium batteries andcadmium telluridesolar panels, the use of cadmium is generally decreasing. These declines have been due to competing technologies, cadmium'stoxicity in certain forms and concentration and resulting regulations.[16]
Indium is achemical element with the symbolIn andatomic number 49. This rare, very soft, malleable and easilyfusibleother metal is chemically similar togallium andthallium, and shows the intermediate properties between these two. Indium was discovered in 1863 and named for theindigo blue line in its spectrum that was the first indication of its existence in zinc ores, as a new and unknown element. The metal was first isolated in the following year. Zinc ores continue to be the primary source of indium, where it is found in compound form. Very rarely the element can be found as grains of native (free) metal, but these are not of commercial importance.
Indium's current primary application is to form transparent electrodes fromindium tin oxide inliquid crystal displays andtouchscreens, and this use largely determines its global mining production. It is widely used in thin-films to form lubricated layers (duringWorld War II it was widely used to coat bearings in high-performanceaircraft). It is also used for making particularly low melting point alloys, and is a component in some lead-free solders.
Indium is not known to be used by any organism. In a similar way to aluminium salts, indium(III) ions can be toxic to the kidney when given by injection, but oral indium compounds do not have the chronic toxicity of salts of heavy metals, probably due to poor absorption in basic conditions. Radioactive indium-111 (in very small amounts on a chemical basis) is used innuclear medicine tests, as aradiotracer to follow the movement of labeled proteins andwhite blood cells in the body.
Tin is achemical element with the symbolSn (forLatin:stannum) andatomic number 50. It is amain-group metal ingroup 14 of theperiodic table. Tin shows chemical similarity to both neighboring group 14 elements,germanium andlead and has two possibleoxidation states, +2 and the slightly more stable +4. Tin is the 49th most abundant element and has, with 10 stable isotopes, the largest number of stableisotopes in the periodic table. Tin is obtained chiefly from themineralcassiterite, where it occurs astin dioxide, SnO2.
This silvery,malleablepost-transition metal is not easilyoxidized in air and is used to coat other metals to preventcorrosion. The firstalloy, used in large scale since 3000 BC, wasbronze, an alloy of tin andcopper. After 600 BC pure metallic tin was produced.Pewter, which is an alloy of 85–90% tin with the remainder commonly consisting of copper,antimony and lead, was used fortableware from theBronze Age until the 20th century. In modern times tin is used in many alloys, most notably tin/lead softsolders, typically containing 60% or more of tin. Another large application for tin is corrosion-resistanttin plating of steel. Because of its low toxicity, tin-plated metal is also used for food packaging, giving the name totin cans, which are made mostly of steel.
Antimony (Latin:stibium) is a toxicchemical element with the symbolSb and anatomic number of 51. A lustrous greymetalloid, it is found in nature mainly as thesulfide mineralstibnite (Sb2S3). Antimony compounds have been known since ancient times and were used for cosmetics, metallic antimony was also known but mostly identified aslead.
For some time China has been the largest producer of antimony and its compounds, with most production coming from theXikuangshan Mine inHunan. Antimony compounds are prominent additives for chlorine and bromine containingfire retardants found in many commercial and domestic products. The largest application for metallic antimony is as alloying material for lead and tin. It improves the properties of the alloys which are used as insolders, bullets andball bearings. An emerging application is the use of antimony inmicroelectronics.
Tellurium is achemical element that has the symbolTe andatomic number 52. A brittle, mildly toxic, rare, silver-whitemetalloid which looks similar totin, tellurium is chemically related toselenium andsulfur. It is occasionally found in native form, as elemental crystals. Tellurium is far more common in the universe than on Earth. Its extremerarity in the Earth's crust, comparable to that ofplatinum, is partly due to its high atomic number, but also due to its formation of a volatilehydride which caused the element to be lost to space as a gas during the hot nebular formation of the planet.
Tellurium was discovered inTransylvania (today part ofRomania) in 1782 byFranz-Joseph Müller von Reichenstein in a mineral containing tellurium andgold.Martin Heinrich Klaproth named the new element in 1798 after the Latin word for "earth",tellus. Gold telluride minerals (responsible for the name ofTelluride, Colorado) are the most notable natural gold compounds. However, they are not a commercially significant source of tellurium itself, which is normally extracted as by-product ofcopper andlead production.
Tellurium is commercially primarily used inalloys, foremost in steel and copper to improve machinability. Applications insolar panels and as asemiconductor material also consume a considerable fraction of tellurium production.
Iodine is achemical element with the symbolI andatomic number 53. The name is fromGreekἰοειδήςioeidēs, meaning violet or purple, due to the color of elemental iodine vapor.[17]
Iodine and its compounds are primarily used innutrition, and industrially in the production ofacetic acid and certain polymers. Iodine's relatively high atomic number, low toxicity, and ease of attachment to organic compounds have made it a part of manyX-ray contrast materials in modern medicine. Iodine has only onestable isotope. A number of iodine radioisotopes are also used in medical applications.
Iodine is found on Earth mainly as the highly water-soluble iodide I−, which concentrates it in oceans and brine pools. Like the otherhalogens, free iodine occurs mainly as adiatomic molecule I2, and then only momentarily after being oxidized from iodide by an oxidant like free oxygen. In the universe and on Earth, iodine's high atomic number makes it a relativelyrare element. However, its presence in ocean water has given it a role in biology (see below).
Xenon is achemical element with thesymbolXe andatomic number 54. A colorless, heavy, odorlessnoble gas, xenon occurs in theEarth's atmosphere in trace amounts.[18] Although generally unreactive, xenon can undergo a fewchemical reactions such as the formation ofxenon hexafluoroplatinate, the firstnoble gas compound to be synthesized.[19][20][21]
Naturally occurring xenon consists ofnine stable isotopes. There are also over 40 unstable isotopes that undergoradioactive decay. The isotope ratios of xenon are an important tool for studying the early history of theSolar System.[22] Radioactivexenon-135 is produced fromiodine-135 as a result ofnuclear fission, and it acts as the most significantneutron absorber innuclear reactors.[23]
Xenon is used inflash lamps[24] andarc lamps,[25] and as ageneral anesthetic.[26] The firstexcimer laser design used a xenondimer molecule (Xe2) as itslasing medium,[27] and the earliestlaser designs used xenon flash lamps aspumps.[28] Xenon is also being used to search for hypotheticalweakly interacting massive particles[29] and as thepropellant forion thrusters inspacecraft.[30]
Rubidium, strontium, yttrium, zirconium, and niobium have no biological role. Yttrium can cause lung disease in humans.
Molybdenum-containing enzymes are used as catalysts by some bacteria to break thechemical bond in atmospheric molecularnitrogen, allowing biologicalnitrogen fixation. At least 50 molybdenum-containing enzymes are now known in bacteria and animals, though only the bacterial and cyanobacterial enzymes are involved in nitrogen fixation. Owing to the diverse functions of the remainder of the enzymes, molybdenum is a required element for life in higher organisms (eukaryotes), though not in all bacteria.
Technetium, ruthenium, rhodium, palladium, and silver have no biological role. Although cadmium has no known biological role in higher organisms, a cadmium-dependentcarbonic anhydrase has been found in marinediatoms. Rats fed a tin-free diet exhibited improper growth, but the evidence for essentiality is otherwise limited.[31][32] Indium has no biological role and can be toxic as well as antimony.
Tellurium has no biological role, although fungi can incorporate it in place of sulfur and selenium intoamino acids such astellurocysteine andtelluromethionine.[33] In humans, tellurium is partly metabolized intodimethyl telluride, (CH3)2Te, a gas with agarlic-like odor which is exhaled in the breath of victims of tellurium toxicity or exposure.
Iodine is the heaviestessential element utilized widely by life in biological functions (onlytungsten, employed in enzymes by a few species of bacteria, is heavier). Iodine's rarity in many soils, due to initial low abundance as a crust-element, and also leaching of soluble iodide by rainwater, has led to many deficiency problems in land animals and inland human populations.Iodine deficiency affects about two billion people and is the leading preventable cause ofintellectual disabilities.[34] Iodine is required by higher animals, which use it to synthesizethyroid hormones, which contain the element. Because of this function,radioisotopes of iodine are concentrated in thethyroid gland along with nonradioactive iodine. The radioisotopeiodine-131, which has a highfission product yield, concentrates in the thyroid, and is one of the mostcarcinogenic ofnuclear fission products.
Xenon has no biological role, and is used as ageneral anaesthetic.
{{cite book}}:|author= has generic name (help){{cite book}}:|author= has generic name (help){{cite web}}:|author= has generic name (help) (public domain text){{cite book}}:|author= has generic name (help)
