Tell about potassium in English

The first element of the fourth row (period) is potassium. The name potassium comes from a substance called Potash. That compound that has been used for hundreds of years and has the chemical formula KOH. Even though we have been using potash for centuries, Davy officially discovered potassium in 1807. In fact, potassium is never found by itself in nature. It is always bonded to other elements. Once isolated, Davy found potassium to be one of the softer metals with a silver color.
Potassium is a little tricky to remember on the periodic table because the symbol is " K".

Atomic Number: 19

Atomic Weight: 39.0983

Melting Point: 336.53 K (63.38°C or 146.08°F)

Boiling Point: 1032 K (759°C or 1398°F)

Density: 0.89 grams per cubic centimeter

Phase at Room Temperature: Solid

Element Classification: Metal

Period Number: 4 Group Number: 1 Group Name: Alkali Metal

History and Uses:

Although potassium is the eighth most abundant element on earth and comprises about 2.1% of the earth's crust, it is a very reactive element and is never found free in nature. Metallic potassium was first isolated by Sir Humphry Davy in 1807 through the electrolysis of molten caustic potash (KOH). A few months after discovering potassium, Davy used the same method to isolate sodium. Potassium can be obtained from the minerals sylvite (KCl), carnallite (KCl·MgCl₂·6H₂O), langbeinite (K₂Mg₂(SO₄)₃) and polyhalite (K₂Ca₂Mg(SO₄)₄·2H₂O). These minerals are often found in ancient lake and sea beds. Caustic potash, another important source of potassium, is primarily mined in Germany, New Mexico, California and Utah.

Pure potassium is a soft, waxy metal that can be easily cut with a knife. It reacts with oxygen to form potassium superoxide (KO₂) and with water to form potassium hydroxide (KOH), hydrogen gas and heat. Enough heat is produced to ignite the hydrogen gas. To prevent it from reacting with the oxygen and water in the air, samples of metallic potassium are usually stored submerged in mineral oil.

Potassium forms an alloy with sodium (NaK) that is used as a heat transfer medium in some types of nuclear reactors

65) Magnesium is a chemical element with symbol Mg and atomic number 12. It is a shiny gray solid which bears a close physical resemblance to the other five elements in the second column (Group 2, or alkaline earth metals) of the periodic table: they each have the same electron configuration in their outer electron shell producing a similar crystal structure.

Magnesium is the ninth most abundant element in the universe.^[4][5] It is synthesized in large, aging stars from the sequential addition of three helium nuclei to a carbon nucleus. When such a star explodes as a supernova, much of its magnesium is expelled into the interstellar medium, where it can be recycled into new star systems. Consequently, magnesium is the eighth most abundant element in the Earth's crust^[6] and the fourth most common element in the Earth (below iron, oxygen and silicon), making up 13% of the planet's mass and a large fraction of the planet's mantle. It is the third most abundant element dissolved in seawater, after sodium and chlorine.^[

66. Calcium is a chemical element with symbol Ca and atomic number 20. Calcium is a soft gray alkaline earth metal, fifth-most-abundant element by mass in the Earth's crust. The ion Ca²⁺ is also the fifth-most-abundant dissolved ion in seawater by both molarity and mass, after sodium, chloride, magnesium, and sulfate.^[3] Free calcium metal is too reactive to occur in nature. Calcium is produced in the explosions at the end of the life of massive stars

Calcium is essential for living organisms, in particular in cell physiology, where movement of the calcium ion into and out of the cytoplasm functions as a signal for many cellular processes. As a major material used in mineralization of bone, teeth andshells, calcium is the most abundant metal by mass in many animals. In chemical terms, calcium is reactive and soft for a metal; though harder than lead, it can be cut with a knife with difficulty. It is a silvery metallic element that must be extracted byelectrolysis from a fused salt like calcium chloride.^[4] Once produced, it rapidly forms a gray-white oxide and nitride coating when exposed to air. In bulk form (typically as chips or " turnings"), the metal is somewhat difficult to ignite, more so even than magnesium chips; but, when lit, the metal burns in air with a brilliant high-intensity orange-red light. Calcium metal reacts with water, generating hydrogen gas at a rate rapid enough to be noticeable, but not fast enough at room temperature to generate much heat, making it useful for generating hydrogen. With a density of 1.54 g/cm³, ^[6] calcium is the lightest of the alkaline earth metals; magnesium (specific gravity 1.74) and beryllium (1.84) are denser though lighter in atomic mass. From strontium onward, the alkali earth metals become denser with increasing atomic mass.Calcium has two allotropes.^[7]Calcium has a higher electrical resistivity than copper or aluminium, yet weight-for-weight, due to its much lower density, it is a better conductor than either. Its use as such in terrestrial applications is usually limited by its high reactivity with air; however, it has potential for use as wiring in off-world applications. Calcium, combined with phosphate, forming hydroxylapatite, is the mineral portion of human and animal bones and teeth. The mineral portion of some corals can also be transformed into hydroxylapatite.

Calcium hydroxide (Ca(OH)₂) (slaked lime) is used in many chemical refinery processes and is made by heating limestone at high temperature (above 825 °C) and then carefully adding water to it. When lime is mixed with sand, it hardens into a mortarand is turned into plaster by carbon dioxide uptake. Mixed with other compounds, lime forms an important part of Portland cement.

Calcium carbonate (CaCO₃) is one of the common compounds of calcium. It is heated to form quicklime (CaO), which is then added to water (H₂O). This forms another material known as slaked lime (Ca(OH)₂), which is an inexpensive base material used throughout the chemical industry. Chalk, marble, and limestone are all forms of calcium carbonate.

When water percolates through limestone or other soluble carbonate rocks, it partially dissolves the rock and causes cave formation with their characteristic stalactites andstalagmites, and also forms hard water. Other important calcium compounds are calcium nitrate, calcium sulfide, calcium chloride, calcium carbide, calcium cyanamide and calcium hypochlorite.

A few calcium compounds where calcium is in the oxidation state +1 have also been investigated recently.^[2] Charlotte Froese Fischer predicted that a Ca⁻ ion would be stable; this ion was discovered experimentally in 1987.^[11]

67. Iron is a chemical element with symbol Fe (from Latin: ferrum) and atomic number 26. It is a metal in the first transition series. It is by mass the most common element on Earth, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust.

Like other group 8 elements, iron exists in a wide range of oxidation states, − 2 to +6, although +2 and +3 are the most common. Elemental iron occurs in meteoroids and other low oxygen environments, but is reactive to oxygen and water. Fresh iron surfaces appear lustrous silvery-gray, but oxidize in normal air to give hydrated iron oxides, commonly known as rust. Unlike many other metals which form passivating oxide layers, iron oxides occupy more volume than the metal and thus flake off, exposing fresh surfaces for corrosion. Pure iron is relatively soft, but is unobtainable by smelting. Iron chemical compounds have many uses. Iron oxide mixed with aluminium powder can be ignited to create a thermite reaction, used in welding and purifying ores. Iron forms binary compounds with the halogens and the chalcogens. Among its organometallic compounds is ferrocene, the first sandwich compound discovered.

68) Copper is a chemical element with symbol Cu (from Latin: cuprum) and atomic number 29. It is a ductile metal with very highthermal and electrical conductivity. Pure copper is soft and malleable; a freshly exposed surface has a reddish-orange color. It is used as a conductor of heat and electricity, a building material, and a constituent of various metal alloys. Chemical Unoxidized copper wire (left) and oxidized copper wire (right).The East Tower of the Royal Observatory, Edinburgh. The contrast between the refurbished copper installed in 2010 and the green color of the original 1894 copper is clearly seen. Copper does not react with water but it does slowly react with atmospheric oxygen to form a layer of brown-black copper oxide which, unlike the rust which forms when iron is exposed to moist air, protects the underlying copper from more extensive corrosion. A green layer of verdigris (copper carbonate) can often be seen on old copper constructions such as the Statue of Liberty.^[10] Coppertarnishes when exposed to sulfides, which react with it to form various copper sulfides.^[11]

Сурак

Barium is a chemical element with symbol Ba and atomic number 56. It is the fifth element in Group 2, a soft silvery metallicalkaline earth metal. Because of its high chemical reactivity barium is never found in nature as a free element. Its hydroxide was known in pre-modern history as baryta; this substance does not occur as a mineral, but can be prepared by heating barium carbonate. Barium is a soft, silvery-white metal, with a slight golden shade when ultrapure.^{[3]: 2}The silvery-white color of barium metal rapidly vanishes upon oxidation in air yielding a dark gray oxide layer. Barium has a medium specific weight and good electrical conductivity. Ultrapure barium is very hard to

70.silver. Chemists classify silver as a transition metal. The transition metals are elements between Groups 2 and 13 in the periodic table. The periodic table is a chart that shows how chemical elements are related to one another. More than 40 elements, all metals, fall within the transition metal range.Silver is also classified as a precious metal. Precious metals are not very abundant in the Earth's crust. They are attractive and not very chemically active. These properties make the metal desirable in jewelry, coins, and art. About a half dozen metals near silver in the periodic table are also precious metals. These include gold, platinum, palladium, rhodium, and indium .PRONUNCIATION
SIL-verToday, the most important use of silver is in photography. Three silver compounds used in photography are silver chloride (AgCl), silver bromide (AgBr), and silver iodide (AgI). Silver is also used to make electrical equipment, mirrors, medical and dental equipment, and jewelry. It is often used to make alloys with gold for some of these applications. An alloy is made by melting and mixing two or more metals. The mixture has properties different from those of the individual metals. Silver also occurs as a free metal, but much less often than gold or copper. At some point, humans learned to extract silver from its ores. But that discovery must have occurred very early on in human history. Archaeologists (scientists who study ancient civilizations) have found silver objects dating to about 3400 B.C. in Egypt. Drawings on some of the oldest pyramids show men working with metal, probably extracting silver from its ores. Physical properties. Silver is a soft, white metal with a shiny surface. It is the most ductile and most malleable metal. Ductile means capable of being drawn into thin wires. Malleable means capable of being hammered into thin sheets. Silver has two other unique properties. It conducts heat and electricity better than any other element. It also reflects light very well. Silver's melting point is 961.5°C (1, 762°F) and its boiling point is about 2, 000 to 2, 200°C (3, 600 to 4, 000°F). Its density is 10.49 grams per cubic centimeter.Drawings on some of the oldest pyramids show men working with metal, probably extracting silver from its ores.Chemical propertiesSilver is a very inactive metal. It does not react with oxygen in the air under normal circumstances. It does react slowly with sulfur compounds in the air, however. The product of this reaction is silver sulfide (Ag ₂ S), a black compound. The tarnish that develops over time on silverware and other silver-plated objects is silver sulfide.Silver does not react readily with water, acids, or many other compounds. It does not burn except as silver powder.

71.Gold is a chemical element with symbol Au (from Latin: aurum) and atomic number 79. In its purest form, it is a bright, slightly reddish yellow, dense, soft, malleable and ductile metal. Chemically, gold is a transition metal and a group 11 element. It is one of the least reactive chemical elements, and is 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. It occurs in a solid solution series with the native element silver (as electrum) and also naturally alloyed with copper and palladium. Less commonly, it occurs in minerals as gold compounds, often with tellurium (gold tellurides).

Gold's atomic number of 79 makes it one of the higher atomic number elements that occur naturally in the universe. It is thought to have been produced in supernova nucleosynthesis and to have been present in the dust from which the Solar System formed. Because the Earth was molten when it was just formed, almost all of the gold present in the early Earth probably sank into the planetary core. Therefore most of the gold that is present today in the Earth's crust and mantle is thought to have been delivered to Earth later, by asteroid impacts during the late heavy bombardment, about 4 billion years ago.

Gold’s high malleability, ductility, resistance to corrosion and most other chemical reactions, and conductivity of electricity have led to its continued use in corrosion resistant electrical connectors in all types of computerized devices (its chief industrial use). Gold is also used in infrared shielding, colored-glass production, and gold leafing. Certain gold salts are still used as anti-inflammatories in medicine.

72) Zinc, in commerce also spelter, is a chemical element with symbol Zn and atomic number 30. It is the first element of group 12 of the periodic table. In some respects zinc is chemically similar to magnesium: its ion is of similar size and its only common oxidation state is +2. Zinc is the 24th most abundant element in Earth's crust and has five stable isotopes. The most common zinc ore is sphalerite (zinc blende), a zinc sulfide mineral. The largest mineable amounts are found in Australia, Asia, and the United States. Zinc production includes froth flotation of the ore, roasting, and final extraction using electricity(electrowinning). The element is normally found in association with other base metals such as copper and leadin ores.^[19] Zinc is a chalcophile, meaning the element has a low affinity for oxides and prefers to bond with sulfides. Chalcophiles formed as the crust solidified under the reducingconditions of the early Earth's atmosphere.^[20] Sphalerite, which is a form of zinc sulfide, is the most heavily mined zinc-containing ore because its concentrate contains 60–62% zinc.^[19]

Other minerals from which zinc is extracted include smithsonite (zinc carbonate), hemimorphite (zinc silicate), wurtzite (another zinc sulfide), and sometimes hydrozincite (basiczinc carbonate).^[21] With the exception of wurtzite, all these other minerals were formed as a result of weathering processes on the primordial zinc sulfides.

73. Tin is a chemical element with the symbol Sn (for Latin: stannum) and atomic number 50. It is a main group metal in group 14of the periodic table. Tin shows a chemical similarity to both neighboring group-14 elements, germanium and lead, and has two possible oxidation 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 stable isotopes in the periodic table. It is a silvery, malleable other metal that is not easily oxidized in air, obtained chiefly from the mineral cassiterite where it occurs as tin dioxide, SnO₂.

The first alloy used on a large scale since 3000 BC was bronze, an alloy of tin and copper. 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 for flatware from the Bronze Age until the 20th century. In modern times, tin is used in many alloys, most notably tin/lead soft solders, which are typically 60% or more tin. Another large application for tin is corrosion-resistant tin plating of steel. Because of its low toxicity, tin-plated metal is commonly used for food packaging as tin cans, which are made mostly of steel.

74 Lead (/lɛ d/) is a chemical element in the carbon group with symbol Pb (from Latin: plumbum) and atomic number 82. Lead is a soft, malleable and heavy post-transition metal. Metallic lead has a bluish-white color after being freshly cut, but it soontarnishes to a dull grayish color when exposed to air. Lead has a shiny chrome-silver luster when it is melted into a liquid. It is also the heaviest non-radioactive element.

Lead is used in building construction, lead-acid batteries, bullets and shot, 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 one isotope with a half-life that is so long (over one billion times the estimated age of the universe) that it can be considered stable. Lead's four stable isotopes have 82 protons, a magic number in the nuclear shell model of atomic nuclei. The isotope lead-208 also has 126 neutrons, another magic number, and is hence double magic, a property that grants it enhanced stability: lead-208 is the heaviest known stable isotope.

If ingested, lead is poisonous to animals and humans, damaging the nervous system and causing brain disorders. Excessive lead also causes blood disorders in mammals. 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. Lead is a bright and silvery metal with a very slight shade of blue in a dry atmosphere.^[2] Upon contact with air, it begins to tarnish by forming a complex mixture of compounds depending on the conditions. The color of the compounds can vary. The tarnish layer can contain significant amounts of carbonates and hydroxycarbonates. Lead's characteristic properties include high density, softness, ductility and malleability, poor electrical conductivity compared to other metals, high corrosion resistance, and ability to react with organic chemicals. Lead occurs naturally on Earth exclusively in the form of four observationally stable isotopes: lead-204, -206, -207, and -208.^[14]All four could theoretically undergo alpha decay with release of energy, but this has not been observed for any of them.^[15]Three of these isotopes also found in three of the four major decay chains: lead-206, -207 and -208 are final decay products of uranium-238, uranium-235, and thorium-232, respectively. Since the amounts of them in nature depend also on other elements' presence, the isotopic composition of natural lead varies by sample: in particular, the relative amount of lead-206 varies between 20.84% and 27.78%. Lead is classified as a post-transition metal and is also a member of the carbon group. Massive lead forms a protective oxide layer, but finely powdered highly purified lead can ignite in air. Melted lead is oxidized in air to lead monoxide. All chalcogens oxidize lead upon heating.^[16]

Fluorine reacts with lead at room temperature, forming lead (II) fluoride.^[17] The reaction with chlorine is similar, although it needs heating: thanks to the chloride layer, lead persistence against chlorine surpasses that of copper or steel up to 300 °C (570 °F).^[16]

75. Mercury is a chemical element with symbol Hg and atomic number 80. It is commonly known as quicksilver and was formerly named hydrargyrum (/haɪ ˈ drɑ rdʒ ə rə m/).^[3] A heavy, silvery d-block element, mercury is the only metallic element 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, gallium, and rubidium melt just above room temperature.

Mercury occurs in deposits throughout the world mostly as cinnabar (mercuric sulfide). The red pigment vermilion, a pure form of mercuric sulfide, is mostly obtained by reaction of mercury (produced by reduction from cinnabar) with sulfur.Mercury poisoning can result from exposure to water-soluble forms of mercury (such as mercuric chloride ormethylmercury), inhalation of mercury vapor, or eating seafood contaminated with mercury.

Mercury is used in thermometers, barometers, manometers, sphygmomanometers, float valves, mercury switches, mercury relays, fluorescent lamps 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 favour of alternatives such asalcohol- or galinstan-filled glass thermometers and thermistor- or infrared-based electronic instruments. Likewise, mechanical pressure gauges and electronic strain gauge sensors have replaced mercury sphygmomanometers. Mercury remains in use in scientific research applications and in amalgam material for dental restoration in some locales. It is used in lighting: electricity passed through mercury vapor in a fluorescent lamp produces short-wave ultraviolet light which then causes the phosphor in the tube to fluoresce, making visible light. Mercury is a heavy, silvery-white metal. As compared to other metals, it is a poor conductor of heat, but a fair conductor of electricity.^[4] Mercury has a freezing pointof − 38.83 °C and a boiling point of 356.73 °C, ^[5][6][7] both exceptionally low for a metal, and it is the only elemental metal known to melt at a generally cold temperature. In addition, mercury's boiling point of 629.88 K (674.11 °F) is the lowest for any metal.^[8] A complete explanation of this delves deep into the realm ofquantum physics, but it can be summarized as follows: mercury has a uniqueelectron configuration where electrons fill up all the available 1s, 2s, 2p, 3s, 3p, 3d, 4s, 4p, 4d, 4f, 5s, 5p, 5d, and 6s subshells. Because this configuration strongly resists removal of an electron, mercury behaves similarly to noble gas elements, which form weak bonds and hence melt at relatively low temperatures. Mercury does not react with most acids, such as dilute sulfuric acid, although oxidizing acids such as concentrated sulfuric acid and nitric acid or aqua regia dissolve it to give sulfate, nitrate, and chloride salts. Like silver, mercury reacts with atmospheric hydrogen sulfide. Mercury even reacts with solid sulfur flakes, which are used in mercury spill kits to absorb mercury vapors (spill kits also use activated carbon and powdered zinc). There are seven stable isotopes of mercury with 202Hg being the most abundant (29.86%). The longest-lived radioisotopes are 194Hg with a half-life of 444 years, and 203 Hg with a half-life of 46.612 days. Most of the remaining radioisotopes have half-lives that are less than a day. 199Hg and 201Hg are the most often studied NMR-active nuclei, having spins of¹⁄ ₂ and ³⁄ ₂ respectively.^[4]