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Period 6 element

January 05, 2023

Period 6 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

A period 6 element is one of the chemical elements in the sixth row (or period) of the periodic table of the elements, including the lanthanides. 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 sixth period contains 32 elements, tied for the most with period 7, beginning with caesium and ending with radon. Lead is currently the last stable element; all subsequent elements are radioactive. For bismuth, however, its only primordial isotope, 209Bi, has a half-life of more than 1019 years, over a billion times longer than the current age of the universe. As a rule, period 6 elements fill their 6s shells first, then their 4f, 5d, and 6p shells, in that order; however, there are exceptions, such as gold.

Properties

This period contains the lanthanides, also known as the rare earths. Many lanthanides are known for their magnetic properties, such as neodymium. Many period 6 transition metals are very valuable, such as gold, however many period 6 other metals are incredibly toxic, such as thallium. Period 6 contains the last stable element, lead. All subsequent elements in the periodic table are radioactive. After bismuth, which has a half-life or more than 1019 years, polonium, astatine, and radon are some of the shortest-lived and rarest elements known; less than a gram of astatine is estimated to exist on earth at any given time.[1]

Atomic characteristics

Chemical element Block Electron configuration
55 Cs Caesium s-block [Xe] 6s1
56 Ba Barium s-block [Xe] 6s2
57 La Lanthanum f-block [a] [Xe] 5d1 6s2 [b]
58 Ce Cerium f-block [Xe] 4f1 5d1 6s2 [b]
59 Pr Praseodymium f-block [Xe] 4f3 6s2
60 Nd Neodymium f-block [Xe] 4f4 6s2
61 Pm Promethium f-block [Xe] 4f5 6s2
62 Sm Samarium f-block [Xe] 4f6 6s2
63 Eu Europium f-block [Xe] 4f7 6s2
64 Gd Gadolinium f-block [Xe] 4f7 5d1 6s2 [b]
65 Tb Terbium f-block [Xe] 4f9 6s2
66 Dy Dysprosium f-block [Xe] 4f10 6s2
67 Ho Holmium f-block [Xe] 4f11 6s2
68 Er Erbium f-block [Xe] 4f12 6s2
69 Tm Thulium f-block [Xe] 4f13 6s2
70 Yb Ytterbium f-block [Xe] 4f14 6s2
71 Lu Lutetium d-block [a] [Xe] 4f14 5d1 6s2
72 Hf Hafnium d-block [Xe] 4f14 5d2 6s2
73 Ta Tantalum d-block [Xe] 4f14 5d3 6s2
74 W Tungsten d-block [Xe] 4f14 5d4 6s2
75 Re Rhenium d-block [Xe] 4f14 5d5 6s2
76 Os Osmium d-block [Xe] 4f14 5d6 6s2
77 Ir Iridium d-block [Xe] 4f14 5d7 6s2
78 Pt Platinum d-block [Xe] 4f14 5d9 6s1 [b]
79 Au Gold d-block [Xe] 4f14 5d10 6s1 [b]
80 Hg Mercury d-block [Xe] 4f14 5d10 6s2
81 Tl Thallium p-block [Xe] 4f14 5d10 6s2 6p1
82 Pb Lead p-block [Xe] 4f14 5d10 6s2 6p2
83 Bi Bismuth p-block [Xe] 4f14 5d10 6s2 6p3
84 Po Polonium p-block [Xe] 4f14 5d10 6s2 6p4
85 At Astatine p-block [Xe] 4f14 5d10 6s2 6p5
86 Rn Radon p-block [Xe] 4f14 5d10 6s2 6p6
  • a In many periodic tables, the f-block is erroneously shifted one element to the right, so that lanthanum and actinium become d-block elements, and Ce–Lu and Th–Lr form the f-block tearing the d-block into two very uneven portions. This is a holdover from early erroneous measurements of electron configurations.[2] Lev Landau and Evgeny Lifshitz pointed out in 1948 that lutetium is not an f-block element,[3] and since then physical, chemical, and electronic evidence has overwhelmingly supported that the f-block contains the elements La–Yb and Ac–No,[2][4] as shown here and as supported by International Union of Pure and Applied Chemistry reports dating from 1988[4] and 2021.[5]
  • b An exception to the Madelung rule.

s-block elements

Caesium

Main article: Caesium

Caesium or cesium[note 1] is the chemical element with the symbol Cs and atomic number 55. It is a soft, silvery-gold alkali metal with a melting point of 28 °C (82 °F), which makes it one of only five elemental metals that are liquid at (or near) room temperature.[note 2] Caesium is an alkali metal and has physical and chemical properties similar to those of rubidium and potassium. The metal is extremely reactive and pyrophoric, reacting with water even at−116 °C (−177 °F). It is the least electronegative element having a stable isotope, caesium-133. Caesium is mined mostly from pollucite, while the radioisotopes, especially caesium-137, a fission product, are extracted from waste produced by nuclear reactors.

Two German chemists, Robert Bunsen and Gustav Kirchhoff, discovered caesium in 1860 by the newly developed method of flame spectroscopy. The first small-scale applications for caesium have been as a "getter" in vacuum tubes and in photoelectric cells. In 1967, a specific frequency from the emission spectrum of caesium-133 was chosen to be used in the definition of the second by the International System of Units. Since then, caesium has been widely used in atomic clocks.

Since the 1990s, the largest application of the element has been as caesium formate for drilling fluids. It has a range of applications in the production of electricity, in electronics, and in chemistry. The radioactive isotope caesium-137 has a half-life of about 30 years and is used in medical applications, industrial gauges, and hydrology. Although the element is only mildly toxic, it is a hazardous material as a metal and its radioisotopes present a high health risk in case of radioactivity releases.

Barium

Main article: Barium

Barium is a chemical element with the symbol Ba and atomic number 56. It is the fifth element in Group 2, a soft silvery metallic alkaline earth metal. Barium is never found in nature in its pure form due to its reactivity with air. Its oxide is historically known as baryta but it reacts with water and carbon dioxide and is not found as a mineral. The most common naturally occurring minerals are the very insoluble barium sulfate, BaSO4 (barite), and barium carbonate, BaCO3(witherite). Barium's name originates from Greek barys (βαρύς), meaning "heavy", describing the high density of some common barium-containing ores.

Barium has few industrial applications, but the metal has been historically used to scavenge air in vacuum tubes. Barium compounds impart a green color to flames and have been used in fireworks. Barium sulfate is used for its density, insolubility, and X-ray opacity. It is used as an insoluble heavy additive to oil well drilling mud, and in purer form, as an X-ray radiocontrast agent for imaging the human gastrointestinal tract. Soluble barium compounds are poisonous due to release of the soluble barium ion, and have been used as rodenticides. New uses for barium continue to be sought. It is a component of some "high temperature" YBCOsuperconductors, and electroceramics.

f-block elements (lanthanides)

Main article: Lanthanides

The lanthanide or lanthanoid (IUPAC nomenclature)[10] series comprises the fifteen metallic chemical elements with atomic numbers 57 through 71, from lanthanum through lutetium.[1]: 240 [11][12] These fifteen elements, along with the chemically similar elements scandium and yttrium, are often collectively known as the rare-earth elements.

The informal chemical symbol Ln is used in general discussions of lanthanide chemistry. All but one of the lanthanides are f-block elements, corresponding to the filling of the 4f electron shell; lanthanum, a d-block element, is also generally considered to be a lanthanide due to its chemical similarities with the other fourteen. All lanthanide elements form trivalent cations, Ln3+, whose chemistry is largely determined by the ionic radius, which decreases steadily from lanthanum to lutetium.

Chemical element La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu
Atomic number 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71
Image                            
Density (g/cm3) 6.162 6.770 6.77 7.01 7.26 7.52 5.244 7.90 8.23 8.540 8.79 9.066 9.32 6.90 9.841
Melting point (°C) 920 795 935 1024 1042 1072 826 1312 1356 1407 1461 1529 1545 824 1652
Atomic electron configuration* 5d1 4f15d1 4f3 4f4 4f5 4f6 4f7 4f75d1 4f9 4f10 4f11 4f12 4f13 4f14 4f145d1
Ln3+ electron configuration*[13] 4f0[14] 4f1 4f2 4f3 4f4 4f5 4f6 4f7 4f8 4f9 4f10 4f11 4f12 4f13

4f14

Ln3+ radius (pm)[15] 103 102 99 98.3 97 95.8 94.7 93.8 92.3 91.2 90.1 89 88 86.8 86.1
  • Between initial [Xe] and final 6s2 electronic shells

The lanthanide elements are the group of elements with atomic number increasing from 57 (lanthanum) to 71 (lutetium). They are termed lanthanide because the lighter elements in the series are chemically similar to lanthanum. Strictly speaking, both lanthanum and lutetium have been labeled as group 3 elements, because they both have a single valence electron in the d shell. However, both elements are often included in any general discussion of the chemistry of the lanthanide elements.

In presentations of the periodic table, the lanthanides and the actinides are customarily shown as two additional rows below the main body of the table,[1] with placeholders or else a selected single element of each series (either lanthanum or lutetium, and either actinium or lawrencium, respectively) shown in a single cell of the main table, between barium and hafnium, and radium and rutherfordium, respectively. This convention is entirely a matter of aesthetics and formatting practicality; a rarely used wide-formatted periodic table inserts the lanthanide and actinide series in their proper places, as parts of the table's sixth and seventh rows (periods).

d-block elements

Lutetium

Main article: Lutetium

Lutetium (/ljuːˈtiːʃiəm/ lew-TEE-shee-əm) is a chemical element with the symbol Lu and atomic number 71. It is the last element in the lanthanide series, which, along with the lanthanide contraction, explains several important properties of lutetium, such as it having the highest hardness or density among lanthanides. Unlike other lanthanides, which lie in the f-block of the periodic table, this element lies in the d-block; however, lanthanum is sometimes placed on the d-block lanthanide position. Chemically, lutetium is a typical lanthanide: its only common oxidation state is +3, seen in its oxide, halides and other compounds. In an aqueous solution, like compounds of other late lanthanides, soluble lutetium compounds form a complex with nine water molecules.

Lutetium was independently discovered in 1907 by French scientist Georges Urbain, Austrian mineralogist Baron Carl Auer von Welsbach, and American chemist Charles James. All of these men found lutetium as an impurity in the mineral ytterbia, which was previously thought to consist entirely of ytterbium. The dispute on the priority of the discovery occurred shortly after, with Urbain and von Welsbach accusing each other of publishing results influenced by the published research of the other; the naming honor went to Urbain as he published his results earlier. He chose the name lutecium for the new element but in 1949 the spelling of element 71 was changed to lutetium. In 1909, the priority was finally granted to Urbain and his names were adopted as official ones; however, the name cassiopeium (or later cassiopium) for element 71 proposed by von Welsbach was used by many German scientists until the 1950s. Like other lanthanides, lutetium is one of the elements that traditionally were included in the classification "rare earths."

Lutetium is rare and expensive; consequently, it has few specific uses. For example, a radioactive isotope lutetium-176 is used in nuclear technology to determine the age of meteorites. Lutetium usually occurs in association with the element yttrium and is sometimes used in metal alloys and as a catalyst in various chemical reactions. 177Lu-DOTA-TATE is used for radionuclide therapy (see Nuclear medicine) on neuroendocrine tumours.

Hafnium

Main article: Hafnium

Hafnium is a chemical element with the symbol Hf and atomic number 72. A lustrous, silvery gray, tetravalent transition metal, hafnium chemically resembles zirconium and is found in zirconium minerals. Its existence was predicted by Dmitri Mendeleev in 1869. Hafnium was the penultimate stable isotope element to be discovered (rhenium was identified two years later). Hafnium is named for Hafnia, the Latin name for "Copenhagen", where it was discovered.

Hafnium is used in filaments and electrodes. Some semiconductor fabrication processes use its oxide for integrated circuits at 45 nm and smaller feature lengths. Some superalloys used for special applications contain hafnium in combination with niobium, titanium, or tungsten.

Hafnium's large neutron capture cross-section makes it a good material for neutron absorption in control rods in nuclear power plants, but at the same time requires that it be removed from the neutron-transparent corrosion-resistant zirconium alloys used in nuclear reactors.

Tantalum

Main article: Tantalum

Tantalum is a chemical element with the symbol Ta and atomic number 73. Previously known as tantalium, the name comes from Tantalus, a character from Greek mythology.[16] Tantalum is a rare, hard, blue-gray, lustrous transition metal that is highly corrosion resistant. It is part of the refractory metals group, which are widely used as minor component in alloys. The chemical inertness of tantalum makes it a valuable substance for laboratory equipment and a substitute for platinum, but its main use today is in tantalum capacitors in electronic equipment such as mobile phones, DVD players, video game systems and computers. Tantalum, always together with the chemically similar niobium, occurs in the minerals tantalite, columbite and coltan (a mix of columbite and tantalite).

Tungsten

Main article: Tungsten

Tungsten, also known as wolfram, is a chemical element with the chemical symbol W and atomic number 74. The word tungsten comes from the Swedish language tung sten directly translatable to heavy stone,[17] though the name is volfram in Swedish to distinguish it from Scheelite, in Swedish alternatively named tungsten.

A hard, rare metal under standard conditions when uncombined, tungsten is found naturally on Earth only in chemical compounds. It was identified as a new element in 1781, and first isolated as a metal in 1783. Its important ores include wolframite and scheelite. The free element is remarkable for its robustness, especially the fact that it has the highest melting point of all the non-alloyed metals and the second highest of all the elements after carbon. Also remarkable is its high density of 19.3 times that of water, comparable to that of uranium and gold, and much higher (about 1.7 times) than that of lead.[18] Tungsten with minor amounts of impurities is often brittle[19] and hard, making it difficult to work. However, very pure tungsten, though still hard, is more ductile, and can be cut with a hard-steel hacksaw.[20]

The unalloyed elemental form is used mainly in electrical applications. Tungsten's many alloys have numerous applications, most notably in incandescent light bulb filaments, X-ray tubes (as both the filament and target), electrodes in TIG welding, and superalloys. Tungsten's hardness and high density give it military applications in penetrating projectiles. Tungsten compounds are most often used industrially as catalysts.

Tungsten is the only metal from the third transition series that is known to occur in biomolecules, where it is used in a few species of bacteria. It is the heaviest element known to be used by any living organism. Tungsten interferes with molybdenum and copper metabolism, and is somewhat toxic to animal life.[21][22]

Rhenium

Main article: Rhenium

Rhenium is a chemical element with the symbol Re and atomic number 75. It is a silvery-white, heavy, third-row transition metal in group 7 of the periodic table. With an estimated average concentration of 1 part per billion (ppb), rhenium is one of the rarest elements in the Earth's crust. The free element has the third-highest melting point and highest boiling point of any element. Rhenium resembles manganese chemically and is obtained as a by-product of molybdenum and copper ore's extraction and refinement. Rhenium shows in its compounds a wide variety of oxidation states ranging from −1 to +7.

Discovered in 1925, rhenium was the last stable element to be discovered. It was named after the river Rhine in Europe.

Nickel-based superalloys of rhenium are used in the combustion chambers, turbine blades, and exhaust nozzles of jet engines, these alloys contain up to 6% rhenium, making jet engine construction the largest single use for the element, with the chemical industry's catalytic uses being next-most important. Because of the low availability relative to demand, rhenium is among the most expensive of metals, with an average price of approximately US$4,575 per kilogram (US$142.30 per troy ounce) as of August 2011; it is also of critical strategic military importance, for its use in high performance military jet and rocket engines.[23]

Osmium

Main article: Osmium

Osmium is a chemical element with the symbol Os and atomic number 76. It is a hard, brittle, blue-gray or blue-black transition metal in the platinum family and is the densest naturally occurring element, with a density of 22.59 g/cm3 (slightly greater than that of iridium and twice that of lead). It is found in nature as an alloy, mostly in platinum ores; its alloys with platinum, iridium, and other platinum group metals are employed in fountain pen tips, electrical contacts, and other applications where extreme durability and hardness are needed.[24]

Iridium

Main article: Iridium

Iridium is the chemical element with atomic number 77, and is represented by the symbol Ir. A very hard, brittle, silvery-white transition metal of the platinum family, iridium is the second-densest element (after osmium) and is the most corrosion-resistant metal, even at temperatures as high as 2000 °C. Although only certain molten salts and halogens are corrosive to solid iridium, finely divided iridium dust is much more reactive and can be flammable.

Iridium was discovered in 1803 among insoluble impurities in natural platinum. Smithson Tennant, the primary discoverer, named the iridium for the goddess Iris, personification of the rainbow, because of the striking and diverse colors of its salts. Iridium is one of the rarest elements in the Earth's crust, with annual production and consumption of only three tonnes. 191
Ir and 193
Ir are the only two naturally occurring isotopes of iridium as well as the only stable isotopes; the latter is the more abundant of the two.

The most important iridium compounds in use are the salts and acids it forms with chlorine, though iridium also forms a number of organometallic compounds used in industrial catalysis, and in research. Iridium metal is employed when high corrosion resistance at high temperatures is needed, as in high-end spark plugs, crucibles for recrystallization of semiconductors at high temperatures, and electrodes for the production of chlorine in the chloralkali process. Iridium radioisotopes are used in some radioisotope thermoelectric generators.

Iridium is found in meteorites with an abundance much higher than its average abundance in the Earth's crust. For this reason the unusually high abundance of iridium in the clay layer at the Cretaceous–Paleogene boundary gave rise to the Alvarez hypothesis that the impact of a massive extraterrestrial object caused the extinction of dinosaurs and many other species 66 million years ago. It is thought that the total amount of iridium in the planet Earth is much higher than that observed in crustal rocks, but as with other platinum group metals, the high density and tendency of iridium to bond with iron caused most iridium to descend below the crust when the planet was young and still molten.

Platinum

Main article: Platinum

Platinum is a chemical element with the chemical symbol Pt and an atomic number of 78.

Its name is derived from the Spanish term platina, which is literally translated into "little silver".[25][26] It is a dense, malleable, ductile, precious, gray-white transition metal.

Platinum has six naturally occurring isotopes. It is one of the rarest elements in the Earth's crust and has an average abundance of approximately 5 μg/kg. It is the least reactive metal. It occurs in some nickel and copper ores along with some native deposits, mostly in South Africa, which accounts for 80% of the world production.

As a member of the platinum group of elements, as well as of the group 10 of the periodic table of elements, platinum is generally non-reactive. It exhibits a remarkable resistance to corrosion, even at high temperatures, and as such is considered a noble metal. As a result, platinum is often found chemically uncombined as native platinum. Because it occurs naturally in the alluvial sands of various rivers, it was first used by pre-Columbian South American natives to produce artifacts. It was referenced in European writings as early as 16th century, but it was not until Antonio de Ulloa published a report on a new metal of Colombian origin in 1748 that it became investigated by scientists.

Platinum is used in catalytic converters, laboratory equipment, electrical contacts and electrodes, platinum-resistance thermometers, dentistry equipment, and jewelry. Because only a few hundred tonnes are produced annually, it is a scarce material, and is highly valuable and is a major precious metal commodity. Being a heavy metal, it leads to health issues upon exposure to its salts, but due to its corrosion resistance, it is not as toxic as some metals.[27] Its compounds, most notably cisplatin, are applied in chemotherapy against certain types of cancer.[28]

Gold

Main article: Gold

Gold is a dense, soft, shiny, malleable and ductile metal. It is a chemical element with the symbol Au and atomic number 79.

Pure gold has a bright yellow color and luster traditionally considered attractive, which it maintains without oxidizing in air or water. Chemically, gold is a transition metal and a group 11 element. It is one of the least reactive chemical elements solid under standard conditions. The metal therefore occurs often in free elemental (native) form, as nuggets or grains in rocks, in veins and in alluvial deposits. Less commonly, it occurs in minerals as gold compounds, usually with tellurium.

Gold resists attacks by individual acids, but it can be dissolved by the aqua regia (nitro-hydrochloric acid), so named because it dissolves gold. Gold also dissolves in alkaline solutions of cyanide, which have been used in mining. Gold dissolves in mercury, forming amalgam alloys. Gold is insoluble in nitric acid, which dissolves silver and base metals, a property that has long been used to confirm the presence of gold in items, giving rise to the term the acid test.

Gold has been a valuable and highly sought-after precious metal for coinage, jewelry, and other arts since long before the beginning of recorded history. Gold standards have been a common basis for monetary policies throughout human history,[citation needed] later being supplanted by fiat currency starting in the 1930s. The last gold certificate and gold coin currencies were issued in the U.S. in 1932. In Europe, most countries left the gold standard with the start of World War I in 1914 and, with huge war debts, failed to return to gold as a medium of exchange.

A total of 165,000 tonnes of gold have been mined in human history, as of 2009.[29] This is roughly equivalent to 5.3 billion troy ounces or, in terms of volume, about 8500 m3, or a cube 20.4 m on a side. The world consumption of new gold produced is about 50% in jewelry, 40% in investments, and 10% in industry.[30]

Besides its widespread monetary and symbolic functions, gold has many practical uses in dentistry, electronics, and other fields. Its high malleability, ductility, resistance to corrosion and most other chemical reactions, and conductivity of electricity led to many uses of gold, including electric wiring, colored-glass production and even gold leaf eating.

It has been claimed that most of the Earth's gold lies at its core, the metal's high density having made it sink there in the planet's youth. Virtually all of the gold that mankind has discovered is considered to have been deposited later by meteorites which contained the element. This supposedly explains why, in prehistory, gold appeared as nuggets on the earth's surface.[31][32][33][34][35]

Mercury

Main article: Mercury (element)

Mercury is a chemical element with the symbol Hg and atomic number 80. It is also known as quicksilver or hydrargyrum ( < Greek "hydr-" water and "argyros" silver). A heavy, silvery d-block element, mercury is the only metal that is liquid at standard conditions for temperature and pressure; the only other element that is liquid under these conditions is bromine, though metals such as caesium, francium, gallium, and rubidium melt just above room temperature. With a freezing point of −38.83 °C and boiling point of 356.73 °C, mercury has one of the narrowest ranges of its liquid state of any metal.[36][37][38]

Mercury occurs in deposits throughout the world mostly as cinnabar (mercuric sulfide). The red pigment vermilion is mostly obtained by reduction from cinnabar. Cinnabar is highly toxic by ingestion or inhalation of the dust. Mercury poisoning can also result from exposure to water-soluble forms of mercury (such as mercuric chloride or methylmercury), inhalation of mercury vapor, or eating seafood contaminated with mercury.

Mercury is used in thermometers, barometers, manometers, sphygmomanometers, float valves, mercury switches, and other devices though concerns about the element's toxicity have led to mercury thermometers and sphygmomanometers being largely phased out in clinical environments in favor of alcohol-filled, galinstan-filled, digital, or thermistor-based instruments. It remains in use in scientific research applications and in amalgam material for dental restoration. It is used in lighting: electricity passed through mercury vapor in a phosphor tube produces short-wave ultraviolet light which then causes the phosphor to fluoresce, making visible light.

p-block elements

Thallium

Main article: Thallium

Thallium is a chemical element with the symbol Tl and atomic number 81. This soft gray other metal resembles tin but discolors when exposed to air. The two chemists William Crookes and Claude-Auguste Lamy discovered thallium independently in 1861 by the newly developed method of flame spectroscopy. Both discovered the new element in residues of sulfuric acid production.

Approximately 60–70% of thallium production is used in the electronics industry, and the remainder is used in the pharmaceutical industry and in glass manufacturing.[39] It is also used in infrared detectors. Thallium is highly toxic and was used in rat poisons and insecticides. Its use has been reduced or eliminated in many countries because of its nonselective toxicity. Because of its use for murder, thallium has gained the nicknames "The Poisoner's Poison" and "Inheritance Powder" (alongside arsenic).[40]

Lead

Main article: Lead

Lead is a main-group element in the carbon group with the symbol Pb (from Latin: plumbum) and atomic number 82. Lead is a soft, malleable other metal. It is also counted as one of the heavy metals. Metallic lead has a bluish-white color after being freshly cut, but it soon tarnishes to a dull grayish color when exposed to air. Lead has a shiny chrome-silver luster when it is melted into a liquid.

Lead is used in building construction, lead-acid batteries, bullets and shots, weights, as part of solders, pewters, fusible alloys and as a radiation shield. Lead has the highest atomic number of all of the stable elements, although the next higher element, bismuth, has a half-life that is so long (much longer than the age of the universe) that it can be considered stable. Its four stable isotopes have 82 protons, a magic number in the nuclear shell model of atomic nuclei.

Lead, at certain exposure levels, is a poisonous substance to animals as well as for human beings. It damages the nervous system and causes brain disorders. Excessive lead also causes blood disorders in mammals. Like the element mercury, another heavy metal, lead is a neurotoxin that accumulates both in soft tissues and the bones. Lead poisoning has been documented from ancient Rome, ancient Greece, and ancient China.

Bismuth

Main article: Bismuth

Bismuth is a chemical element with symbol Bi and atomic number 83. Bismuth, a trivalent other metal, chemically resembles arsenic and antimony. Elemental bismuth may occur naturally uncombined, although its sulfide and oxide form important commercial ores. The free element is 86% as dense as lead. It is a brittle metal with a silvery white color when newly made, but often seen in air with a pink tinge owing to the surface oxide. Bismuth metal has been known from ancient times, although until the 18th century it was often confused with lead and tin, which each have some of bismusth's bulk physical properties. The etymology is uncertain but possibly comes from Arabic bi ismid meaning having the properties of antimony[41] or German words weisse masse or wismuth meaning "white mass".[42]

Bismuth is the most naturally diamagnetic of all metals, and only mercury has a lower thermal conductivity.

Bismuth has classically been considered to be the heaviest naturally occurring stable element, in terms of atomic mass. Recently, however, it has been found to be very slightly radioactive: its only primordial isotope bismuth-209 decays via alpha decay into thallium-205 with a half-life of more than a billion times the estimated age of the universe.[43]

Bismuth compounds (accounting for about half the production of bismuth) are used in cosmetics, pigments, and a few pharmaceuticals. Bismuth has unusually low toxicity for a heavy metal. As the toxicity of lead has become more apparent in recent years, alloy uses for bismuth metal (presently about a third of bismuth production), as a replacement for lead, have become an increasing part of bismuth's commercial importance.

Polonium

Main article: Polonium

Polonium is a chemical element with the symbol Po and atomic number 84, discovered in 1898 by Marie Skłodowska-Curie and Pierre Curie. A rare and highly radioactive element, polonium is chemically similar to bismuth[44] and tellurium, and it occurs in uraniumores. Polonium has been studied for possible use in heating spacecraft. As it is unstable, all isotopes of polonium are radioactive. There is disagreement as to whether polonium is a post-transition metal or metalloid.[45][46]

Astatine

Main article: Astatine

Astatine is a radioactive chemical element with the symbol At and atomic number 85. It occurs on the Earth only as the result of decay of heavier elements, and decays away rapidly, so much less is known about this element than its upper neighbors in the periodic table. Earlier studies have shown this element follows periodic trends, being the heaviest known halogen, with melting and boiling points being higher than those of lighter halogens.

Until recently most of the chemical characteristics of astatine were inferred from comparison with other elements; however, important studies have already been done. The main difference between astatine and iodine is that the HAt molecule is chemically a hydride rather than a halide; however, in a fashion similar to the lighter halogens, it is known to form ionic astatides with metals. Bonds to nonmetals result in positive oxidation states, with +1 best portrayed by monohalides and their derivatives, while the higher are characterized by bond to oxygen and carbon. Attempts to synthesize astatine fluoride have been met with failure. The second longest-living astatine-211 is the only one to find a commercial use, being useful as an alpha emitter in medicine; however, only extremely small quantities are used, and in larger ones it is very hazardous, as it is intensely radioactive.

Astatine was first produced by Dale R. Corson, Kenneth Ross MacKenzie, and Emilio Segrè in the University of California, Berkeley in 1940. Three years later, it was found in nature; however, with an estimated amount of less than 28 grams (1 oz) at given time, astatine is the least abundant element in Earth's crust among non-transuranium elements. Among astatine isotopes, six (with mass numbers 214 to 219) are present in nature as the result of decay of heavier elements; however, the most stable astatine-210 and the industrially used astatine-211 are not.

Radon

Main article: Radon

Radon is a chemical element with symbol Rn and atomic number 86. It is a radioactive, colorless, odorless, tasteless[citation needed][47] noble gas, occurring naturally as the decay product of uranium or thorium. Its most stable isotope, 222Rn, has a half-life of 3.8 days. Radon is one of the densest substances that remains a gas under normal conditions. It is also the only gas that is radioactive under normal conditions, and is considered a health hazard due to its radioactivity. Intense radioactivity also hindered chemical studies of radon and only a few compounds are known.

Radon is formed as part of the normal radioactive decay chain of uranium and thorium. Uranium and thorium have been around since the earth was formed and their most common isotope has a very long half-life (14.05 billion years). Uranium and thorium, radium, and thus radon, will continue to occur for millions of years at about the same concentrations as they do now.[48] As the radioactive gas of radon decays, it produces new radioactive elements called radon daughters or decay products. Radon daughters are solids and stick to surfaces such as dust particles in the air. If contaminated dust is inhaled, these particles can stick to the airways of the lung and increase the risk of developing lung cancer.[49]

Radon is responsible for the majority of the public exposure to ionizing radiation. It is often the single largest contributor to an individual's background radiation dose, and is the most variable from location to location. Radon gas from natural sources can accumulate in buildings, especially in confined areas such as attics and basements. It can also be found in some spring waters and hot springs.[50]

Epidemiological studies have shown a clear link between breathing high concentrations of radon and incidence of lung cancer. Thus, radon is considered a significant contaminant that affects indoor air quality worldwide. According to the United States Environmental Protection Agency, radon is the second most frequent cause of lung cancer, after cigarette smoking, causing 21,000 lung cancer deaths per year in the United States. About 2,900 of these deaths occur among people who have never smoked. While radon is the second most frequent cause of lung cancer, it is the number one cause among non-smokers, according to EPA estimates.[51]

Biological role

Of the period 6 elements, only tungsten is known to have any biological role in organisms. However, gold, platinum, mercury, and some lanthanides such as gadolinium have applications as drugs.

Toxicity

Most of the period 6 elements are toxic (for instance lead) and produce heavy-element poisoning. Promethium, polonium, astatine and radon are radioactive, and therefore present radioactive hazards.

Notes

  1. ^ Caesium is the spelling recommended by the International Union of Pure and Applied Chemistry (IUPAC).[6] The American Chemical Society (ACS) has used the spelling cesium since 1921,[7][8] following Webster's New International Dictionary. The element was named after the Latin word caesius, meaning "bluish gray". More spelling explanation at ae/oe vs e.
  2. ^ Along with rubidium (39 °C [102 °F]), francium (estimated at 27 °C [81 °F]), mercury (−39 °C [−38 °F]), and gallium (30 °C [86 °F]); bromine is also liquid at room temperature (melting at −7.2 °C, 19 °F) but it is a halogen, not a metal.[9]

References

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January 05, 2023
period, element, period, periodic, table, hydrogen, heliumlithium, beryllium, boron, carbon, nitrogen, oxygen, fluorine, neonsodium, magnesium, aluminium, silicon, phosphorus, sulfur, chlorine, argonpotassium, calcium, scandium, titanium, vanadium, chromium, m. Period 6 in the periodic table Hydrogen HeliumLithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine NeonSodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine ArgonPotassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine KryptonRubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine XenonCaesium 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 RadonFrancium 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 A period 6 element is one of the chemical elements in the sixth row or period of the periodic table of the elements including the lanthanides 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 sixth period contains 32 elements tied for the most with period 7 beginning with caesium and ending with radon Lead is currently the last stable element all subsequent elements are radioactive For bismuth however its only primordial isotope 209Bi has a half life of more than 1019 years over a billion times longer than the current age of the universe As a rule period 6 elements fill their 6s shells first then their 4f 5d and 6p shells in that order however there are exceptions such as gold Contents 1 Properties 2 Atomic characteristics 3 s block elements 3 1 Caesium 3 2 Barium 4 f block elements lanthanides 5 d block elements 5 1 Lutetium 5 2 Hafnium 5 3 Tantalum 5 4 Tungsten 5 5 Rhenium 5 6 Osmium 5 7 Iridium 5 8 Platinum 5 9 Gold 5 10 Mercury 6 p block elements 6 1 Thallium 6 2 Lead 6 3 Bismuth 6 4 Polonium 6 5 Astatine 6 6 Radon 7 Biological role 8 Toxicity 9 Notes 10 ReferencesProperties EditThis period contains the lanthanides also known as the rare earths Many lanthanides are known for their magnetic properties such as neodymium Many period 6 transition metals are very valuable such as gold however many period 6 other metals are incredibly toxic such as thallium Period 6 contains the last stable element lead All subsequent elements in the periodic table are radioactive After bismuth which has a half life or more than 1019 years polonium astatine and radon are some of the shortest lived and rarest elements known less than a gram of astatine is estimated to exist on earth at any given time 1 Atomic characteristics EditChemical element Block Electron configuration55 Cs Caesium s block Xe 6s156 Ba Barium s block Xe 6s257 La Lanthanum f block a Xe 5d1 6s2 b 58 Ce Cerium f block Xe 4f1 5d1 6s2 b 59 Pr Praseodymium f block Xe 4f3 6s260 Nd Neodymium f block Xe 4f4 6s261 Pm Promethium f block Xe 4f5 6s262 Sm Samarium f block Xe 4f6 6s263 Eu Europium f block Xe 4f7 6s264 Gd Gadolinium f block Xe 4f7 5d1 6s2 b 65 Tb Terbium f block Xe 4f9 6s266 Dy Dysprosium f block Xe 4f10 6s267 Ho Holmium f block Xe 4f11 6s268 Er Erbium f block Xe 4f12 6s269 Tm Thulium f block Xe 4f13 6s270 Yb Ytterbium f block Xe 4f14 6s271 Lu Lutetium d block a Xe 4f14 5d1 6s272 Hf Hafnium d block Xe 4f14 5d2 6s273 Ta Tantalum d block Xe 4f14 5d3 6s274 W Tungsten d block Xe 4f14 5d4 6s275 Re Rhenium d block Xe 4f14 5d5 6s276 Os Osmium d block Xe 4f14 5d6 6s277 Ir Iridium d block Xe 4f14 5d7 6s278 Pt Platinum d block Xe 4f14 5d9 6s1 b 79 Au Gold d block Xe 4f14 5d10 6s1 b 80 Hg Mercury d block Xe 4f14 5d10 6s281 Tl Thallium p block Xe 4f14 5d10 6s2 6p182 Pb Lead p block Xe 4f14 5d10 6s2 6p283 Bi Bismuth p block Xe 4f14 5d10 6s2 6p384 Po Polonium p block Xe 4f14 5d10 6s2 6p485 At Astatine p block Xe 4f14 5d10 6s2 6p586 Rn Radon p block Xe 4f14 5d10 6s2 6p6a In many periodic tables the f block is erroneously shifted one element to the right so that lanthanum and actinium become d block elements and Ce Lu and Th Lr form the f block tearing the d block into two very uneven portions This is a holdover from early erroneous measurements of electron configurations 2 Lev Landau and Evgeny Lifshitz pointed out in 1948 that lutetium is not an f block element 3 and since then physical chemical and electronic evidence has overwhelmingly supported that the f block contains the elements La Yb and Ac No 2 4 as shown here and as supported by International Union of Pure and Applied Chemistry reports dating from 1988 4 and 2021 5 b An exception to the Madelung rule s block elements EditCaesium Edit Main article Caesium Caesium or cesium note 1 is the chemical element with the symbol Cs and atomic number 55 It is a soft silvery gold alkali metal with a melting point of 28 C 82 F which makes it one of only five elemental metals that are liquid at or near room temperature note 2 Caesium is an alkali metal and has physical and chemical properties similar to those of rubidium and potassium The metal is extremely reactive and pyrophoric reacting with water even at 116 C 177 F It is the least electronegative element having a stable isotope caesium 133 Caesium is mined mostly from pollucite while the radioisotopes especially caesium 137 a fission product are extracted from waste produced by nuclear reactors Two German chemists Robert Bunsen and Gustav Kirchhoff discovered caesium in 1860 by the newly developed method of flame spectroscopy The first small scale applications for caesium have been as a getter in vacuum tubes and in photoelectric cells In 1967 a specific frequency from the emission spectrum of caesium 133 was chosen to be used in the definition of the second by the International System of Units Since then caesium has been widely used in atomic clocks Since the 1990s the largest application of the element has been as caesium formate for drilling fluids It has a range of applications in the production of electricity in electronics and in chemistry The radioactive isotope caesium 137 has a half life of about 30 years and is used in medical applications industrial gauges and hydrology Although the element is only mildly toxic it is a hazardous material as a metal and its radioisotopes present a high health risk in case of radioactivity releases Barium Edit Main article Barium Barium is a chemical element with the symbol Ba and atomic number 56 It is the fifth element in Group 2 a soft silvery metallic alkaline earth metal Barium is never found in nature in its pure form due to its reactivity with air Its oxide is historically known as baryta but it reacts with water and carbon dioxide and is not found as a mineral The most common naturally occurring minerals are the very insoluble barium sulfate BaSO4 barite and barium carbonate BaCO3 witherite Barium s name originates from Greek barys barys meaning heavy describing the high density of some common barium containing ores Barium has few industrial applications but the metal has been historically used to scavenge air in vacuum tubes Barium compounds impart a green color to flames and have been used in fireworks Barium sulfate is used for its density insolubility and X ray opacity It is used as an insoluble heavy additive to oil well drilling mud and in purer form as an X ray radiocontrast agent for imaging the human gastrointestinal tract Soluble barium compounds are poisonous due to release of the soluble barium ion and have been used as rodenticides New uses for barium continue to be sought It is a component of some high temperature YBCOsuperconductors and electroceramics f block elements lanthanides EditMain article Lanthanides The lanthanide or lanthanoid IUPAC nomenclature 10 series comprises the fifteen metallic chemical elements with atomic numbers 57 through 71 from lanthanum through lutetium 1 240 11 12 These fifteen elements along with the chemically similar elements scandium and yttrium are often collectively known as the rare earth elements The informal chemical symbol Ln is used in general discussions of lanthanide chemistry All but one of the lanthanides are f block elements corresponding to the filling of the 4f electron shell lanthanum a d block element is also generally considered to be a lanthanide due to its chemical similarities with the other fourteen All lanthanide elements form trivalent cations Ln3 whose chemistry is largely determined by the ionic radius which decreases steadily from lanthanum to lutetium Chemical element La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb LuAtomic number 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71Image Density g cm3 6 162 6 770 6 77 7 01 7 26 7 52 5 244 7 90 8 23 8 540 8 79 9 066 9 32 6 90 9 841Melting point C 920 795 935 1024 1042 1072 826 1312 1356 1407 1461 1529 1545 824 1652Atomic electron configuration 5d1 4f15d1 4f3 4f4 4f5 4f6 4f7 4f75d1 4f9 4f10 4f11 4f12 4f13 4f14 4f145d1Ln3 electron configuration 13 4f0 14 4f1 4f2 4f3 4f4 4f5 4f6 4f7 4f8 4f9 4f10 4f11 4f12 4f13 4f14Ln3 radius pm 15 103 102 99 98 3 97 95 8 94 7 93 8 92 3 91 2 90 1 89 88 86 8 86 1Between initial Xe and final 6s2 electronic shellsThe lanthanide elements are the group of elements with atomic number increasing from 57 lanthanum to 71 lutetium They are termed lanthanide because the lighter elements in the series are chemically similar to lanthanum Strictly speaking both lanthanum and lutetium have been labeled as group 3 elements because they both have a single valence electron in the d shell However both elements are often included in any general discussion of the chemistry of the lanthanide elements In presentations of the periodic table the lanthanides and the actinides are customarily shown as two additional rows below the main body of the table 1 with placeholders or else a selected single element of each series either lanthanum or lutetium and either actinium or lawrencium respectively shown in a single cell of the main table between barium and hafnium and radium and rutherfordium respectively This convention is entirely a matter of aesthetics and formatting practicality a rarely used wide formatted periodic table inserts the lanthanide and actinide series in their proper places as parts of the table s sixth and seventh rows periods d block elements EditLutetium Edit Main article Lutetium Lutetium l juː ˈ t iː ʃ i e m lew TEE shee em is a chemical element with the symbol Lu and atomic number 71 It is the last element in the lanthanide series which along with the lanthanide contraction explains several important properties of lutetium such as it having the highest hardness or density among lanthanides Unlike other lanthanides which lie in the f block of the periodic table this element lies in the d block however lanthanum is sometimes placed on the d block lanthanide position Chemically lutetium is a typical lanthanide its only common oxidation state is 3 seen in its oxide halides and other compounds In an aqueous solution like compounds of other late lanthanides soluble lutetium compounds form a complex with nine water molecules Lutetium was independently discovered in 1907 by French scientist Georges Urbain Austrian mineralogist Baron Carl Auer von Welsbach and American chemist Charles James All of these men found lutetium as an impurity in the mineral ytterbia which was previously thought to consist entirely of ytterbium The dispute on the priority of the discovery occurred shortly after with Urbain and von Welsbach accusing each other of publishing results influenced by the published research of the other the naming honor went to Urbain as he published his results earlier He chose the name lutecium for the new element but in 1949 the spelling of element 71 was changed to lutetium In 1909 the priority was finally granted to Urbain and his names were adopted as official ones however the name cassiopeium or later cassiopium for element 71 proposed by von Welsbach was used by many German scientists until the 1950s Like other lanthanides lutetium is one of the elements that traditionally were included in the classification rare earths Lutetium is rare and expensive consequently it has few specific uses For example a radioactive isotope lutetium 176 is used in nuclear technology to determine the age of meteorites Lutetium usually occurs in association with the element yttrium and is sometimes used in metal alloys and as a catalyst in various chemical reactions 177Lu DOTA TATE is used for radionuclide therapy see Nuclear medicine on neuroendocrine tumours Hafnium Edit Main article Hafnium Hafnium is a chemical element with the symbol Hf and atomic number 72 A lustrous silvery gray tetravalent transition metal hafnium chemically resembles zirconium and is found in zirconium minerals Its existence was predicted by Dmitri Mendeleev in 1869 Hafnium was the penultimate stable isotope element to be discovered rhenium was identified two years later Hafnium is named for Hafnia the Latin name for Copenhagen where it was discovered Hafnium is used in filaments and electrodes Some semiconductor fabrication processes use its oxide for integrated circuits at 45 nm and smaller feature lengths Some superalloys used for special applications contain hafnium in combination with niobium titanium or tungsten Hafnium s large neutron capture cross section makes it a good material for neutron absorption in control rods in nuclear power plants but at the same time requires that it be removed from the neutron transparent corrosion resistant zirconium alloys used in nuclear reactors Tantalum Edit Main article Tantalum Tantalum is a chemical element with the symbol Ta and atomic number 73 Previously known as tantalium the name comes from Tantalus a character from Greek mythology 16 Tantalum is a rare hard blue gray lustrous transition metal that is highly corrosion resistant It is part of the refractory metals group which are widely used as minor component in alloys The chemical inertness of tantalum makes it a valuable substance for laboratory equipment and a substitute for platinum but its main use today is in tantalum capacitors in electronic equipment such as mobile phones DVD players video game systems and computers Tantalum always together with the chemically similar niobium occurs in the minerals tantalite columbite and coltan a mix of columbite and tantalite Tungsten Edit Main article Tungsten Tungsten also known as wolfram is a chemical element with the chemical symbol W and atomic number 74 The word tungsten comes from the Swedish language tung sten directly translatable to heavy stone 17 though the name is volfram in Swedish to distinguish it from Scheelite in Swedish alternatively named tungsten A hard rare metal under standard conditions when uncombined tungsten is found naturally on Earth only in chemical compounds It was identified as a new element in 1781 and first isolated as a metal in 1783 Its important ores include wolframite and scheelite The free element is remarkable for its robustness especially the fact that it has the highest melting point of all the non alloyed metals and the second highest of all the elements after carbon Also remarkable is its high density of 19 3 times that of water comparable to that of uranium and gold and much higher about 1 7 times than that of lead 18 Tungsten with minor amounts of impurities is often brittle 19 and hard making it difficult to work However very pure tungsten though still hard is more ductile and can be cut with a hard steel hacksaw 20 The unalloyed elemental form is used mainly in electrical applications Tungsten s many alloys have numerous applications most notably in incandescent light bulb filaments X ray tubes as both the filament and target electrodes in TIG welding and superalloys Tungsten s hardness and high density give it military applications in penetrating projectiles Tungsten compounds are most often used industrially as catalysts Tungsten is the only metal from the third transition series that is known to occur in biomolecules where it is used in a few species of bacteria It is the heaviest element known to be used by any living organism Tungsten interferes with molybdenum and copper metabolism and is somewhat toxic to animal life 21 22 Rhenium Edit Main article Rhenium Rhenium is a chemical element with the symbol Re and atomic number 75 It is a silvery white heavy third row transition metal in group 7 of the periodic table With an estimated average concentration of 1 part per billion ppb rhenium is one of the rarest elements in the Earth s crust The free element has the third highest melting point and highest boiling point of any element Rhenium resembles manganese chemically and is obtained as a by product of molybdenum and copper ore s extraction and refinement Rhenium shows in its compounds a wide variety of oxidation states ranging from 1 to 7 Discovered in 1925 rhenium was the last stable element to be discovered It was named after the river Rhine in Europe Nickel based superalloys of rhenium are used in the combustion chambers turbine blades and exhaust nozzles of jet engines these alloys contain up to 6 rhenium making jet engine construction the largest single use for the element with the chemical industry s catalytic uses being next most important Because of the low availability relative to demand rhenium is among the most expensive of metals with an average price of approximately US 4 575 per kilogram US 142 30 per troy ounce as of August 2011 it is also of critical strategic military importance for its use in high performance military jet and rocket engines 23 Osmium Edit Main article Osmium Osmium is a chemical element with the symbol Os and atomic number 76 It is a hard brittle blue gray or blue black transition metal in the platinum family and is the densest naturally occurring element with a density of 22 59 g cm3 slightly greater than that of iridium and twice that of lead It is found in nature as an alloy mostly in platinum ores its alloys with platinum iridium and other platinum group metals are employed in fountain pen tips electrical contacts and other applications where extreme durability and hardness are needed 24 Iridium Edit Main article Iridium Iridium is the chemical element with atomic number 77 and is represented by the symbol Ir A very hard brittle silvery white transition metal of the platinum family iridium is the second densest element after osmium and is the most corrosion resistant metal even at temperatures as high as 2000 C Although only certain molten salts and halogens are corrosive to solid iridium finely divided iridium dust is much more reactive and can be flammable Iridium was discovered in 1803 among insoluble impurities in natural platinum Smithson Tennant the primary discoverer named the iridium for the goddess Iris personification of the rainbow because of the striking and diverse colors of its salts Iridium is one of the rarest elements in the Earth s crust with annual production and consumption of only three tonnes 191 Ir and 193 Ir are the only two naturally occurring isotopes of iridium as well as the only stable isotopes the latter is the more abundant of the two The most important iridium compounds in use are the salts and acids it forms with chlorine though iridium also forms a number of organometallic compounds used in industrial catalysis and in research Iridium metal is employed when high corrosion resistance at high temperatures is needed as in high end spark plugs crucibles for recrystallization of semiconductors at high temperatures and electrodes for the production of chlorine in the chloralkali process Iridium radioisotopes are used in some radioisotope thermoelectric generators Iridium is found in meteorites with an abundance much higher than its average abundance in the Earth s crust For this reason the unusually high abundance of iridium in the clay layer at the Cretaceous Paleogene boundary gave rise to the Alvarez hypothesis that the impact of a massive extraterrestrial object caused the extinction of dinosaurs and many other species 66 million years ago It is thought that the total amount of iridium in the planet Earth is much higher than that observed in crustal rocks but as with other platinum group metals the high density and tendency of iridium to bond with iron caused most iridium to descend below the crust when the planet was young and still molten Platinum Edit Main article Platinum Platinum is a chemical element with the chemical symbol Pt and an atomic number of 78 Its name is derived from the Spanish term platina which is literally translated into little silver 25 26 It is a dense malleable ductile precious gray white transition metal Platinum has six naturally occurring isotopes It is one of the rarest elements in the Earth s crust and has an average abundance of approximately 5 mg kg It is the least reactive metal It occurs in some nickel and copper ores along with some native deposits mostly in South Africa which accounts for 80 of the world production As a member of the platinum group of elements as well as of the group 10 of the periodic table of elements platinum is generally non reactive It exhibits a remarkable resistance to corrosion even at high temperatures and as such is considered a noble metal As a result platinum is often found chemically uncombined as native platinum Because it occurs naturally in the alluvial sands of various rivers it was first used by pre Columbian South American natives to produce artifacts It was referenced in European writings as early as 16th century but it was not until Antonio de Ulloa published a report on a new metal of Colombian origin in 1748 that it became investigated by scientists Platinum is used in catalytic converters laboratory equipment electrical contacts and electrodes platinum resistance thermometers dentistry equipment and jewelry Because only a few hundred tonnes are produced annually it is a scarce material and is highly valuable and is a major precious metal commodity Being a heavy metal it leads to health issues upon exposure to its salts but due to its corrosion resistance it is not as toxic as some metals 27 Its compounds most notably cisplatin are applied in chemotherapy against certain types of cancer 28 Gold Edit Main article Gold Gold is a dense soft shiny malleable and ductile metal It is a chemical element with the symbol Au and atomic number 79 Pure gold has a bright yellow color and luster traditionally considered attractive which it maintains without oxidizing in air or water Chemically gold is a transition metal and a group 11 element It is one of the least reactive chemical elements solid under standard conditions The metal therefore occurs often in free elemental native form as nuggets or grains in rocks in veins and in alluvial deposits Less commonly it occurs in minerals as gold compounds usually with tellurium Gold resists attacks by individual acids but it can be dissolved by the aqua regia nitro hydrochloric acid so named because it dissolves gold Gold also dissolves in alkaline solutions of cyanide which have been used in mining Gold dissolves in mercury forming amalgam alloys Gold is insoluble in nitric acid which dissolves silver and base metals a property that has long been used to confirm the presence of gold in items giving rise to the term the acid test Gold has been a valuable and highly sought after precious metal for coinage jewelry and other arts since long before the beginning of recorded history Gold standards have been a common basis for monetary policies throughout human history citation needed later being supplanted by fiat currency starting in the 1930s The last gold certificate and gold coin currencies were issued in the U S in 1932 In Europe most countries left the gold standard with the start of World War I in 1914 and with huge war debts failed to return to gold as a medium of exchange A total of 165 000 tonnes of gold have been mined in human history as of 2009 29 This is roughly equivalent to 5 3 billion troy ounces or in terms of volume about 8500 m3 or a cube 20 4 m on a side The world consumption of new gold produced is about 50 in jewelry 40 in investments and 10 in industry 30 Besides its widespread monetary and symbolic functions gold has many practical uses in dentistry electronics and other fields Its high malleability ductility resistance to corrosion and most other chemical reactions and conductivity of electricity led to many uses of gold including electric wiring colored glass production and even gold leaf eating It has been claimed that most of the Earth s gold lies at its core the metal s high density having made it sink there in the planet s youth Virtually all of the gold that mankind has discovered is considered to have been deposited later by meteorites which contained the element This supposedly explains why in prehistory gold appeared as nuggets on the earth s surface 31 32 33 34 35 Mercury Edit Main article Mercury element Mercury is a chemical element with the symbol Hg and atomic number 80 It is also known as quicksilver or hydrargyrum lt Greek hydr water and argyros silver A heavy silvery d block element mercury is the only metal that is liquid at standard conditions for temperature and pressure the only other element that is liquid under these conditions is bromine though metals such as caesium francium gallium and rubidium melt just above room temperature With a freezing point of 38 83 C and boiling point of 356 73 C mercury has one of the narrowest ranges of its liquid state of any metal 36 37 38 Mercury occurs in deposits throughout the world mostly as cinnabar mercuric sulfide The red pigment vermilion is mostly obtained by reduction from cinnabar Cinnabar is highly toxic by ingestion or inhalation of the dust Mercury poisoning can also result from exposure to water soluble forms of mercury such as mercuric chloride or methylmercury inhalation of mercury vapor or eating seafood contaminated with mercury Mercury is used in thermometers barometers manometers sphygmomanometers float valves mercury switches and other devices though concerns about the element s toxicity have led to mercury thermometers and sphygmomanometers being largely phased out in clinical environments in favor of alcohol filled galinstan filled digital or thermistor based instruments It remains in use in scientific research applications and in amalgam material for dental restoration It is used in lighting electricity passed through mercury vapor in a phosphor tube produces short wave ultraviolet light which then causes the phosphor to fluoresce making visible light p block elements EditThallium Edit Main article Thallium Thallium is a chemical element with the symbol Tl and atomic number 81 This soft gray other metal resembles tin but discolors when exposed to air The two chemists William Crookes and Claude Auguste Lamy discovered thallium independently in 1861 by the newly developed method of flame spectroscopy Both discovered the new element in residues of sulfuric acid production Approximately 60 70 of thallium production is used in the electronics industry and the remainder is used in the pharmaceutical industry and in glass manufacturing 39 It is also used in infrared detectors Thallium is highly toxic and was used in rat poisons and insecticides Its use has been reduced or eliminated in many countries because of its nonselective toxicity Because of its use for murder thallium has gained the nicknames The Poisoner s Poison and Inheritance Powder alongside arsenic 40 Lead Edit Main article Lead Lead is a main group element in the carbon group with the symbol Pb from Latin plumbum and atomic number 82 Lead is a soft malleable other metal It is also counted as one of the heavy metals Metallic lead has a bluish white color after being freshly cut but it soon tarnishes to a dull grayish color when exposed to air Lead has a shiny chrome silver luster when it is melted into a liquid Lead is used in building construction lead acid batteries bullets and shots weights as part of solders pewters fusible alloys and as a radiation shield Lead has the highest atomic number of all of the stable elements although the next higher element bismuth has a half life that is so long much longer than the age of the universe that it can be considered stable Its four stable isotopes have 82 protons a magic number in the nuclear shell model of atomic nuclei Lead at certain exposure levels is a poisonous substance to animals as well as for human beings It damages the nervous system and causes brain disorders Excessive lead also causes blood disorders in mammals Like the element mercury another heavy metal lead is a neurotoxin that accumulates both in soft tissues and the bones Lead poisoning has been documented from ancient Rome ancient Greece and ancient China Bismuth Edit Main article Bismuth Bismuth is a chemical element with symbol Bi and atomic number 83 Bismuth a trivalent other metal chemically resembles arsenic and antimony Elemental bismuth may occur naturally uncombined although its sulfide and oxide form important commercial ores The free element is 86 as dense as lead It is a brittle metal with a silvery white color when newly made but often seen in air with a pink tinge owing to the surface oxide Bismuth metal has been known from ancient times although until the 18th century it was often confused with lead and tin which each have some of bismusth s bulk physical properties The etymology is uncertain but possibly comes from Arabic bi ismid meaning having the properties of antimony 41 or German words weisse masse or wismuth meaning white mass 42 Bismuth is the most naturally diamagnetic of all metals and only mercury has a lower thermal conductivity Bismuth has classically been considered to be the heaviest naturally occurring stable element in terms of atomic mass Recently however it has been found to be very slightly radioactive its only primordial isotope bismuth 209 decays via alpha decay into thallium 205 with a half life of more than a billion times the estimated age of the universe 43 Bismuth compounds accounting for about half the production of bismuth are used in cosmetics pigments and a few pharmaceuticals Bismuth has unusually low toxicity for a heavy metal As the toxicity of lead has become more apparent in recent years alloy uses for bismuth metal presently about a third of bismuth production as a replacement for lead have become an increasing part of bismuth s commercial importance Polonium Edit Main article Polonium Polonium is a chemical element with the symbol Po and atomic number 84 discovered in 1898 by Marie Sklodowska Curie and Pierre Curie A rare and highly radioactive element polonium is chemically similar to bismuth 44 and tellurium and it occurs in uraniumores Polonium has been studied for possible use in heating spacecraft As it is unstable all isotopes of polonium are radioactive There is disagreement as to whether polonium is a post transition metal or metalloid 45 46 Astatine Edit Main article Astatine Astatine is a radioactive chemical element with the symbol At and atomic number 85 It occurs on the Earth only as the result of decay of heavier elements and decays away rapidly so much less is known about this element than its upper neighbors in the periodic table Earlier studies have shown this element follows periodic trends being the heaviest known halogen with melting and boiling points being higher than those of lighter halogens Until recently most of the chemical characteristics of astatine were inferred from comparison with other elements however important studies have already been done The main difference between astatine and iodine is that the HAt molecule is chemically a hydride rather than a halide however in a fashion similar to the lighter halogens it is known to form ionic astatides with metals Bonds to nonmetals result in positive oxidation states with 1 best portrayed by monohalides and their derivatives while the higher are characterized by bond to oxygen and carbon Attempts to synthesize astatine fluoride have been met with failure The second longest living astatine 211 is the only one to find a commercial use being useful as an alpha emitter in medicine however only extremely small quantities are used and in larger ones it is very hazardous as it is intensely radioactive Astatine was first produced by Dale R Corson Kenneth Ross MacKenzie and Emilio Segre in the University of California Berkeley in 1940 Three years later it was found in nature however with an estimated amount of less than 28 grams 1 oz at given time astatine is the least abundant element in Earth s crust among non transuranium elements Among astatine isotopes six with mass numbers 214 to 219 are present in nature as the result of decay of heavier elements however the most stable astatine 210 and the industrially used astatine 211 are not Radon Edit Main article Radon Radon is a chemical element with symbol Rn and atomic number 86 It is a radioactive colorless odorless tasteless citation needed 47 noble gas occurring naturally as the decay product of uranium or thorium Its most stable isotope 222Rn has a half life of 3 8 days Radon is one of the densest substances that remains a gas under normal conditions It is also the only gas that is radioactive under normal conditions and is considered a health hazard due to its radioactivity Intense radioactivity also hindered chemical studies of radon and only a few compounds are known Radon is formed as part of the normal radioactive decay chain of uranium and thorium Uranium and thorium have been around since the earth was formed and their most common isotope has a very long half life 14 05 billion years Uranium and thorium radium and thus radon will continue to occur for millions of years at about the same concentrations as they do now 48 As the radioactive gas of radon decays it produces new radioactive elements called radon daughters or decay products Radon daughters are solids and stick to surfaces such as dust particles in the air If contaminated dust is inhaled these particles can stick to the airways of the lung and increase the risk of developing lung cancer 49 Radon is responsible for the majority of the public exposure to ionizing radiation It is often the single largest contributor to an individual s background radiation dose and is the most variable from location to location Radon gas from natural sources can accumulate in buildings especially in confined areas such as attics and basements It can also be found in some spring waters and hot springs 50 Epidemiological studies have shown a clear link between breathing high concentrations of radon and incidence of lung cancer Thus radon is considered a significant contaminant that affects indoor air quality worldwide According to the United States Environmental Protection Agency radon is the second most frequent cause of lung cancer after cigarette smoking causing 21 000 lung cancer deaths per year in the United States About 2 900 of these deaths occur among people who have never smoked While radon is the second most frequent cause of lung cancer it is the number one cause among non smokers according to EPA estimates 51 Biological role EditOf the period 6 elements only tungsten is known to have any biological role in organisms However gold platinum mercury and some lanthanides such as gadolinium have applications as drugs Toxicity EditMost of the period 6 elements are toxic for instance lead and produce heavy element poisoning Promethium polonium astatine and radon are radioactive and therefore present radioactive hazards Notes Edit Caesium is the spelling recommended by the International Union of Pure and Applied Chemistry IUPAC 6 The American Chemical Society ACS has used the spelling cesium since 1921 7 8 following Webster s New International Dictionary The element was named after the Latin word caesius meaning bluish gray More spelling explanation at ae oe vs e Along with rubidium 39 C 102 F francium estimated at 27 C 81 F mercury 39 C 38 F and gallium 30 C 86 F bromine is also liquid at room temperature melting at 7 2 C 19 F but it is a halogen not a metal 9 References Edit a b c Gray Theodore 2009 The Elements A Visual Exploration of Every Known Atom in the Universe New York Black Dog amp Leventhal Publishers ISBN 978 1 57912 814 2 a b William B Jensen 1982 The Positions of Lanthanum Actinium and Lutetium Lawrencium in the Periodic Table J Chem Educ 59 8 634 636 Bibcode 1982JChEd 59 634J doi 10 1021 ed059p634 L D Landau E M Lifshitz 1958 Quantum Mechanics Non Relativistic Theory Vol 3 1st ed Pergamon Press pp 256 7 a b Fluck E 1988 New Notations in the Periodic Table PDF Pure Appl Chem 60 3 431 436 doi 10 1351 pac198860030431 S2CID 96704008 Archived PDF from the original on 25 March 2012 Retrieved 24 March 2012 Scerri Eric 18 January 2021 Provisional Report on Discussions on Group 3 of the Periodic Table PDF Chemistry International 43 1 31 34 doi 10 1515 ci 2021 0115 S2CID 231694898 Archived PDF from the original on 13 April 2021 Retrieved 9 April 2021 International Union of Pure and Applied Chemistry 2005 Nomenclature of Inorganic Chemistry IUPAC Recommendations 2005 Cambridge UK RSC IUPAC ISBN 0 85404 438 8 pp 248 49 Electronic version Coghill Anne M Garson Lorrin R eds 2006 The ACS Style Guide Effective Communication of Scientific Information 3rd ed Washington D C American Chemical Society p 127 ISBN 978 0 8412 3999 9 Coplen T B Peiser H S 1998 History of the recommended atomic weight values from 1882 to 1997 a comparison of differences from current values to the estimated uncertainties of earlier values PDF Pure Appl Chem 70 1 237 257 doi 10 1351 pac199870010237 S2CID 96729044 WebElements Periodic Table of the Elements University of Sheffield Retrieved 2010 12 01 The current IUPAC recommendation is that the name lanthanoid be used rather than lanthanide as the suffix ide is preferred for negative ions whereas the suffix oid indicates similarity to one of the members of the containing family of elements However lanthanide is still favored in most 90 scientific articles and is currently adopted on Wikipedia In the older literature the name lanthanon was often used Lanthanide Archived 2011 09 11 at the Wayback Machine Encyclopaedia Britannica on line Holden Norman E amp Coplen Tyler January February 2004 The Periodic Table of the Elements Chemistry International IUPAC 26 1 8 Archived from the original on February 17 2004 Retrieved March 23 2010 Walter Koechner 2006 Solid state laser engineering Springer pp 47 ISBN 978 0 387 29094 2 Retrieved 15 January 2012 Lanthanum Chemistry Encyclopedia reaction water elements metal gas name atom Chemistryexplained com Retrieved on 2012 01 15 Greenwood Norman N Earnshaw Alan 1997 Chemistry of the Elements 2nd ed Butterworth Heinemann p 1233 ISBN 978 0 08 037941 8 Euripides Orestes Tungsten Oxford English Dictionary Online ed Oxford University Press Subscription or participating institution membership required Daintith John 2005 Facts on File Dictionary of Chemistry 4th ed New York Checkmark Books ISBN 978 0 8160 5649 1 Lassner Erik Schubert Wolf Dieter 1999 low temperature brittleness Tungsten properties chemistry technology of the element alloys and chemical compounds Springer pp 20 21 ISBN 978 0 306 45053 2 Stwertka Albert 2002 A Guide to the elements 2nd ed New York Oxford University Press ISBN 978 0 19 515026 1 McMaster J amp Enemark John H 1998 The active sites of molybdenum and tungsten containing enzymes Current Opinion in Chemical Biology 2 2 201 207 doi 10 1016 S1367 5931 98 80061 6 PMID 9667924 Hille Russ 2002 Molybdenum and tungsten in biology Trends in Biochemical Sciences 27 7 360 367 doi 10 1016 S0968 0004 02 02107 2 PMID 12114025 Rhenium MetalPrices com MetalPrices com Retrieved February 2 2012 Hammond Osmium C R p 4 25 in Lide D R ed 2005 CRC Handbook of Chemistry and Physics 86th ed Boca Raton FL CRC Press ISBN 0 8493 0486 5 platinum Pt Encyclopaedia Britannica Online Encyclopaedia Britannica Inc 2012 Web 24 April 2012 Harper Douglas platinum Online Etymology Dictionary Platinum PDF Wheate N J Walker S Craig G E Oun R 2010 The status of platinum anticancer drugs in the clinic and in clinical trials PDF Dalton Transactions 39 35 8113 27 doi 10 1039 C0DT00292E hdl 2123 14271 PMID 20593091 World Gold Council FAQ www gold org Soos Andy 2011 01 06 Gold Mining Boom Increasing Mercury Pollution Risk Advanced Media Solutions Inc Oilprice com Retrieved 2011 03 26 Meteorites delivered gold to Earth BBC News 2011 09 08 Where does all Earth s gold come from Precious metals the result of meteorite bombardment rock analysis finds http www ees rochester edu ees119 reading2 pdf bare URL PDF Meteor Shower Rained Gold On Ancient Earth Huffington Post 2011 09 10 Willbold Matthias Elliott Tim Moorbath Stephen 2011 The tungsten isotopic composition of the Earth s mantle before the terminal bombardment Nature 477 7363 195 198 Bibcode 2011Natur 477 195W doi 10 1038 nature10399 PMID 21901010 S2CID 4419046 Senese F Why is mercury a liquid at STP General Chemistry Online at Frostburg State University Retrieved May 1 2007 Norrby L J 1991 Why is mercury liquid Or why do relativistic effects not get into chemistry textbooks Journal of Chemical Education 68 2 110 Bibcode 1991JChEd 68 110N doi 10 1021 ed068p110 Lide D R ed 2005 CRC Handbook of Chemistry and Physics 86th ed Boca Raton FL CRC Press pp 4 125 4 126 ISBN 0 8493 0486 5 Chemical fact sheet Thallium Spectrum Laboratories April 2001 Archived from the original on 2008 02 21 Retrieved 2008 02 02 Hasan Heather 2009 The Boron Elements Boron Aluminum Gallium Indium Thallium Rosen Publishing Group p 14 ISBN 978 1 4358 5333 1 Bismuth Web Mineral Retrieved on 2011 12 17 Anthony John W Bideaux Richard A Bladh Kenneth W Nichols Monte C eds Bismuth PDF Handbook of Mineralogy Vol I Elements Sulfides Sulfosalts Chantilly VA US Mineralogical Society of America ISBN 978 0 9622097 0 3 Retrieved December 5 2011 Dume Belle 2003 04 23 Bismuth breaks half life record for alpha decay Physicsweb Polonium Retrieved 2009 05 05 Hawkes Stephen J 2010 Polonium and Astatine Are Not Semimetals Journal of Chemical Education 87 8 783 Bibcode 2010JChEd 87 783H doi 10 1021 ed100308w Characterizing the Elements Los Alamos National Laboratory Retrieved 4 March 2013 Britannica Concise Encyclopedia Encyclopaedia Britannica Britannica Digital Learning 2017 via Credo Reference Toxological profile for radon Archived 2016 04 15 at the Wayback Machine Agency for Toxic Substances and Disease Registry U S Public Health Service In collaboration with U S Environmental Protection Agency December 1990 Public Health Fact Sheet on Radon Health and Human Services Mass Gov Retrieved 2011 12 04 Facts about Radon Facts about Archived from the original on 2005 02 22 Retrieved 2008 09 07 A Citizen s Guide to Radon www epa gov United States Environmental Protection Agency October 12 2010 Retrieved January 29 2012 Retrieved from https en wikipedia org w index php title Period 6 element amp oldid 1129866556, wikipedia, wiki, book, books, library,

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