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Explanation given supra. The source is available in #2 and #3.
Beryllium
Gist
Beryllium is a chemical element with the symbol Be and atomic number 4. It's a relatively rare, hard, and lightweight alkaline earth metal known for its high strength-to-weight ratio and stiffness. Beryllium is used in various applications, including aerospace, nuclear reactors, and precision instruments, due to its unique properties.
Beryllium is a chemical element with the symbol Be and atomic number 4. It is a hard, strong, lightweight, and brittle alkaline earth metal, typically a steel-gray color. It's known for its high melting point, good electrical and thermal conductivity, and transparency to X-rays. Beryllium is used in a variety of high-tech applications, including aerospace components, nuclear reactors, and electronics.
Summary
Beryllium is a chemical element; it has symbol Be and atomic number 4. It is a steel-gray, hard, strong, lightweight and brittle alkaline earth metal. It is a divalent element that occurs naturally only in combination with other elements to form minerals. Gemstones high in beryllium include beryl (aquamarine, emerald, red beryl) and chrysoberyl. It is a relatively rare element in the universe, usually occurring as a product of the spallation of larger atomic nuclei that have collided with cosmic rays. Within the cores of stars, beryllium is depleted as it is fused into heavier elements. Beryllium constitutes about 0.0004 percent by mass of Earth's crust. The world's annual beryllium production of 220 tons is usually manufactured by extraction from the mineral beryl, a difficult process because beryllium bonds strongly to oxygen.
In structural applications, the combination of high flexural rigidity, thermal stability, thermal conductivity and low density (1.85 times that of water) make beryllium a desirable aerospace material for aircraft components, missiles, spacecraft, and satellites. Because of its low density and atomic mass, beryllium is relatively transparent to X-rays and other forms of ionizing radiation; therefore, it is the most common window material for X-ray equipment and components of particle detectors. When added as an alloying element to aluminium, copper (notably the alloy beryllium copper), iron, or nickel, beryllium improves many physical properties. For example, tools and components made of beryllium copper alloys are strong and hard and do not create sparks when they strike a steel surface. In air, the surface of beryllium oxidizes readily at room temperature to form a passivation layer 1–10 nm thick that protects it from further oxidation and corrosion. The metal oxidizes in bulk (beyond the passivation layer) when heated above 500 °C (932 °F), and burns brilliantly when heated to about 2,500 °C (4,530 °F).
The commercial use of beryllium requires the use of appropriate dust control equipment and industrial controls at all times because of the toxicity of inhaled beryllium-containing dusts that can cause a chronic life-threatening allergic disease, berylliosis, in some people. Berylliosis is typically manifested by chronic pulmonary fibrosis and, in severe cases, right sided heart failure and death.
Details
Beryllium (Be), chemical element, the lightest member of the alkaline-earth metals of Group 2 (IIa) of the periodic table, used in metallurgy as a hardening agent and in many outer space and nuclear applications.
Element Properties
atomic number : 4
atomic weight : 9.0121831
melting point : 1,287 °C (2,349 °F)
boiling point : 2,471 °C (4,480 °F)
specific gravity : 1.85 at 20 °C (68 °F)
oxidation state : +2
Occurrence, properties, and uses
Beryllium is a steel-gray metal that is quite brittle at room temperature, and its chemical properties somewhat resemble those of aluminum. It does not occur free in nature. Beryllium is found in beryl and emerald, minerals that were known to the ancient Egyptians. Although it had long been suspected that the two minerals were similar, chemical confirmation of this did not occur until the late 18th century. Emerald is now known to be a green variety of beryl. Beryllium was discovered (1798) as the oxide by French chemist Nicolas-Louis Vauquelin in beryl and in emeralds and was isolated (1828) as the metal independently by German chemist Friedrich Wöhler and French chemist Antoine A.B. Bussy by the reduction of its chloride with potassium. Beryllium is widely distributed in Earth’s crust and is estimated to occur in Earth’s igneous rocks to the extent of 0.0002 percent. Its cosmic abundance is 20 on the scale in which silicon, the standard, is 1,000,000. The United States has about 60 percent of the world’s beryllium and is by far the largest producer of beryllium; other major producing countries include China, Mozambique, and Brazil.
There are about 30 recognized minerals containing beryllium, including beryl (Al2Be3Si6O18, a beryllium aluminum silicate), bertrandite (Be4Si2O7(OH)2, a beryllium silicate), phenakite (Be2SiO4), and chrysoberyl (BeAl2O4). (The precious forms of beryl, emerald and aquamarine, have a composition closely approaching that given above, but industrial ores contain less beryllium; most beryl is obtained as a by-product of other mining operations, with the larger crystals being picked out by hand.) Beryl and bertrandite have been found in sufficient quantities to constitute commercial ores from which beryllium hydroxide or beryllium oxide is industrially produced. The extraction of beryllium is complicated by the fact that beryllium is a minor constituent in most ores (5 percent by mass even in pure beryl, less than 1 percent by mass in bertrandite) and is tightly bound to oxygen. Treatment with acids, roasting with complex fluorides, and liquid-liquid extraction have all been employed to concentrate beryllium in the form of its hydroxide. The hydroxide is converted to fluoride via ammonium beryllium fluoride and then heated with magnesium to form elemental beryllium. Alternatively, the hydroxide can be heated to form the oxide, which in turn can be treated with carbon and chlorine to form beryllium chloride; electrolysis of the molten chloride is then used to produce the metal. The element is purified by vacuum melting.
Beryllium is the only stable light metal with a relatively high melting point. Although it is readily attacked by alkalies and nonoxidizing acids, beryllium rapidly forms an adherent oxide surface film that protects the metal from further air oxidation under normal conditions. These chemical properties, coupled with its excellent electrical conductivity, high heat capacity and conductivity, good mechanical properties at elevated temperatures, and very high modulus of elasticity (one-third greater than that of steel), make it valuable for structural and thermal applications. Beryllium’s dimensional stability and its ability to take a high polish have made it useful for mirrors and camera shutters in space, military, and medical applications and in semiconductor manufacturing. Because of its low atomic weight, beryllium transmits X-rays 17 times as well as aluminum and has been extensively used in making windows for X-ray tubes. Beryllium is fabricated into gyroscopes, accelerometers, and computer parts for inertial guidance instruments and other devices for missiles, aircraft, and space vehicles, and it is used for heavy-duty brake drums and similar applications in which a good heat sink is important. Its ability to slow down fast neutrons has found considerable application in nuclear reactors.
Much beryllium is used as a low-percentage component of hard alloys, especially with copper as the main constituent but also with nickel- and iron-based alloys, for products such as springs. Beryllium-copper (2 percent beryllium) is made into tools for use when sparking might be dangerous, as in powder factories. Beryllium itself does not reduce sparking, but it strengthens the copper (by a factor of 6), which does not form sparks upon impact. Small amounts of beryllium added to oxidizable metals generate protecting surface films, reducing inflammability in magnesium and tarnishing in silver alloys.
Neutrons were discovered (1932) by British physicist Sir James Chadwick as particles ejected from beryllium bombarded by alpha particles from a radium source. Since then beryllium mixed with an alpha emitter such as radium, plutonium, or americium has been used as a neutron source. The alpha particles released by radioactive decay of radium atoms react with atoms of beryllium to give, among the products, neutrons with a wide range of energies—up to about 5 × 106 electron volts (eV). If radium is encapsulated, however, so that none of the alpha particles reach beryllium, neutrons of energy less than 600,000 eV are produced by the more-penetrating gamma radiation from the decay products of radium. Historically important examples of the use of beryllium/radium neutron sources include the bombardment of uranium by German chemists Otto Hahn and Fritz Strassmann and Austrian-born physicist Lise Meitner, which led to the discovery of nuclear fission (1939), and the triggering in uranium of the first controlled-fission chain reaction by Italian-born physicist Enrico Fermi (1942).
The only naturally occurring isotope is the stable beryllium-9, although 11 other synthetic isotopes are known. Their half-lives range from 1.5 million years (for beryllium-10, which undergoes beta decay) to {6.7} × {10}^{-17} second for beryllium-8 (which decays by two-proton emission). The decay of beryllium-7 (53.2-day half-life) in the Sun is the source of observed solar neutrinos.
Additional Information:
Appearance
Beryllium is a silvery-white metal. It is relatively soft and has a low density.
Uses
Beryllium is used in alloys with copper or nickel to make gyroscopes, springs, electrical contacts, spot-welding electrodes and non-sparking tools. Mixing beryllium with these metals increases their electrical and thermal conductivity.
Other beryllium alloys are used as structural materials for high-speed aircraft, missiles, spacecraft and communication satellites.
Beryllium is relatively transparent to X-rays so ultra-thin beryllium foil is finding use in X-ray lithography. Beryllium is also used in nuclear reactors as a reflector or moderator of neutrons.
The oxide has a very high melting point making it useful in nuclear work as well as having ceramic applications.
Biological role
Beryllium and its compounds are toxic and carcinogenic. If beryllium dust or fumes are inhaled, it can lead to an incurable inflammation of the lungs called berylliosis.
Natural abundance
Beryllium is found in about 30 different mineral species. The most important are beryl (beryllium aluminium silicate) and bertrandite (beryllium silicate). Emerald and aquamarine are precious forms of beryl.
The metal is usually prepared by reducing beryllium fluoride with magnesium metal.
Clean Quotes - I
1. Let everyone sweep in front of his own door, and the whole world will be clean. - Johann Wolfgang von Goethe
2. Water is life, and clean water means health. - Audrey Hepburn
3. That's been one of my mantras - focus and simplicity. Simple can be harder than complex: You have to work hard to get your thinking clean to make it simple. But it's worth it in the end because once you get there, you can move mountains. - Steve Jobs
4. Keep close to Nature's heart... and break clear away, once in awhile, and climb a mountain or spend a week in the woods. Wash your spirit clean. - John Muir
5. We learned about gratitude and humility - that so many people had a hand in our success, from the teachers who inspired us to the janitors who kept our school clean... and we were taught to value everyone's contribution and treat everyone with respect. - Michelle Obama
6. Better keep yourself clean and bright; you are the window through which you must see the world. - George Bernard Shaw
7. I aways rewrite each day up to the point where I stopped. When it is all finished, naturally you go over it. You get another chance to correct and rewrite when someone else types it, and you see it clean in type. The last chance is in the proofs. You're grateful for these different chances. - Ernest Hemingway
8. Lemons clean everything. It's the greatest disinfectant. - Sandra Bullock.
Subatomic particle
Gist
Subatomic particles are particles smaller than an atom. They include protons, neutrons, and electrons, which are the fundamental building blocks of atoms. Additionally, there are other subatomic particles like quarks, leptons (including electrons, muons, and neutrinos), and bosons, some of which are fundamental and others are composite particles.
Summary
A subatomic particle is any of various self-contained units of matter or energy that are the fundamental constituents of all matter. Subatomic particles include electrons, the negatively charged, almost massless particles that nevertheless account for most of the size of the atom, and they include the heavier building blocks of the small but very dense nucleus of the atom, the positively charged protons and the electrically neutral neutrons. But these basic atomic components are by no means the only known subatomic particles. Protons and neutrons, for instance, are themselves made up of elementary particles called quarks, and the electron is only one member of a class of elementary particles that also includes the muon and the neutrino. More-unusual subatomic particles—such as the positron, the antimatter counterpart of the electron—have been detected and characterized in cosmic ray interactions in Earth’s atmosphere. The field of subatomic particles has expanded dramatically with the construction of powerful particle accelerators to study high-energy collisions of electrons, protons, and other particles with matter. As particles collide at high energy, the collision energy becomes available for the creation of subatomic particles such as mesons and hyperons. Finally, completing the revolution that began in the early 20th century with theories of the equivalence of matter and energy, the study of subatomic particles has been transformed by the discovery that the actions of forces are due to the exchange of “force” particles such as photons and gluons. More than 200 subatomic particles have been detected—most of them highly unstable, existing for less than a millionth of a second—as a result of collisions produced in cosmic ray reactions or particle accelerator experiments. Theoretical and experimental research in particle physics, the study of subatomic particles and their properties, has given scientists a clearer understanding of the nature of matter and energy and of the origin of the universe.
The current understanding of the state of particle physics is integrated within a conceptual framework known as the Standard Model. The Standard Model provides a classification scheme for all the known subatomic particles based on theoretical descriptions of the basic forces of matter.
Details
In physics, a subatomic particle is a particle smaller than an atom. According to the Standard Model of particle physics, a subatomic particle can be either a composite particle, which is composed of other particles (for example, a baryon, like a proton or a neutron, composed of three quarks; or a meson, composed of two quarks), or an elementary particle, which is not composed of other particles (for example, quarks; or electrons, muons, and tau particles, which are called leptons). Particle physics and nuclear physics study these particles and how they interact. Most force-carrying particles like photons or gluons are called bosons and, although they have quanta of energy, do not have rest mass or discrete diameters (other than pure energy wavelength) and are unlike the former particles that have rest mass and cannot overlap or combine which are called fermions. The W and Z bosons, however, are an exception to this rule and have relatively large rest masses at approximately 80 GeV/c^2 and 90 GeV/c^2 respectively.
Experiments show that light could behave like a stream of particles (called photons) as well as exhibiting wave-like properties. This led to the concept of wave–particle duality to reflect that quantum-scale particles behave both like particles and like waves; they are occasionally called wavicles to reflect this.
Another concept, the uncertainty principle, states that some of their properties taken together, such as their simultaneous position and momentum, cannot be measured exactly. Interactions of particles in the framework of quantum field theory are understood as creation and annihilation of quanta of corresponding fundamental interactions. This blends particle physics with field theory.
Even among particle physicists, the exact definition of a particle has diverse descriptions. These professional attempts at the definition of a particle include:
* A particle is a collapsed wave function
* A particle is an excitation of a quantum field
* A particle is an irreducible representation of the Poincaré group
* A particle is an observed thing.
Additional Information
Subatomic Particles are the particles inside an atom. They are self-contained units of matter or energy and are the fundamental constituents of all matter. Initially, the atom was considered to be the fundamental particle which constitutes all the matter. However, with later experiments and discoveries, it was revealed that the atom is itself constituted of several particles such as Electrons, Protons and Neutrons. Further research in particle physics revealed that even protons and neutrons are composite particles, made up of some other subatomic elementary particles.
Types of Subatomic Particles
Atoms are considered the basic building blocks of matter. It was John Dalton who in 1803 postulated that an atom is indestructible and is the fundamental unit of matter. This was proved wrong by J.J. Thomson in 1897.
Electrons
Electrons were discovered by J.J Thomson after many experiments involving cathode rays. He demonstrated the ratio of mass to electric charge of cathode rays. He confirmed that cathode rays are fundamental particles that are negatively charged; these cathode rays became known as electrons.... Read more at: https://vajiramandravi.com/upsc-exam/subatomic-particles/
Protons
Eugene Goldstein in 1886 showed the existence of a positively charged particle in an atom. However, the actual discovery of protons is credited to Ernest Rutherford during his experiment on the scattering of α-particles.
Neutrons
It was inevitable from Rutherford’s experiment that there must be a neutral, sub-nuclear particle with a mass closely equal to protons. James Chadwick in 1932 discovered the neutrons.
Fundamental Particles
Subatomic particles can be further divided into elementary (fundamental) particles and composite particles (made up of elementary particles).
Q: What does the dentist of the year get?
A: A little plaque.
* * *
Q: What game did the dentist play when she was a child?
A: Caps and robbers.
* * *
Q: What do you call a dentist who doesn't like tea?
A: Denis.
* * *
Q: What did the dentist say to the computer?
A: This won't hurt a byte.
* * *
Q: What is a dentist's office?
A: A filling station.
* * *
Hi,
#10451. What does the term in Biology Autotroph mean?
#10452. What does the term in Biology B cell mean?
Hi,
#5641. What does the noun broth mean?
#5642. What does the noun brown paper mean?
Hi,
#2412. What does the medical term Hyperextension (exercise) mean?
Hi,
#9678.
Hi,
#6183.
Hi,
2424.
2333) Otoscope
Gist
An otoscope is a tool which shines a beam of light to help visualize and examine the condition of the ear canal and eardrum. Examining the ear can reveal the cause of symptoms such as an earache, the ear feeling full, or hearing loss.
During an ear exam, a tool called an otoscope is used to look at the outer ear canal and eardrum. The otoscope has a light, a magnifying lens, and a funnel-shaped viewing piece with a narrow, pointed end called a speculum.
Summary
An otoscope is a medical device used to examine the ear canal and eardrum. It consists of a light source, a magnifying lens, and a speculum (a cone-shaped viewing piece). The otoscope allows healthcare providers to visualize the ear canal and identify potential issues such as infections, blockages, or other abnormalities.
Otoscopy is the formal name for an ear examination. Although the ear is a small part of the body, it consists of many parts.1
* The external ear contains the external auditory canal, a tube connecting the outer part of the ear to the middle ear.
* The eardrum, or tympanic membrane, separates the outer ear from the middle ear.
* The middle ear, or tympanic cavity, contains the eustachian tube.
* The eustachian tube connects the middle of the ear to the ear to the back of the nose.
* The inner ear has small parts that are responsible for hearing and balance.
There are several reasons you may get an otoscopy:
* For a routine physical
* To check for an ear infection
* To find out the cause of ear symptoms, like an earache or feeling of fullness
* To screen for hearing loss
* To examine for excess wax in the ear canal
* To check for an object blocking the ear canal
Details
An otoscope or auriscope is a medical device used by healthcare professionals to examine the ear canal and eardrum. This may be done as part of routine physical examinations, or for evaluating specific ear complaints, such as earaches, sense of fullness in the ear, or hearing loss.
Usage:
Function
An otoscope enables viewing and examination of the ear canal and tympanic membrane (eardrum). As the eardrum is the border between the external ear canal and the middle ear, its characteristics can indicate various diseases of the middle ear space. Otoscopic examination can help diagnose conditions such as acute otitis media (infection of the middle ear), otitis externa (infection of the outer ear), traumatic perforation of the eardrum, and cholesteatoma.
The presence of cerumen (earwax), shed skin, pus, canal skin edema, foreign bodies, and various ear diseases, can obscure the view of the eardrum and thus compromise the value of otoscopy done with a common otoscope, but can confirm the presence of obstructing symptoms.
Otoscopes can also be used to examine patients' noses (avoiding the need for a separate nasal speculum) and upper throats (by removing the speculum).
Method of use
The most common otoscopes consist of a handle and a head. The head contains a light source and a magnifying lens, typically around 8 diopters (3× magnification), to help illuminate and enlarge ear structures. The distal (front) end of the otoscope has an attachment for disposable plastic ear specula.
The examiner first pulls on the pinna (usually the earlobe, side or top) to straighten the ear canal, and then inserts the ear speculum side of the otoscope into the outer ear. It is important to brace the index or little finger of the hand holding the otoscope against the patient's head to avoid injuring the ear canal. The examiner then looks through the lens on the rear of the instrument to see inside the ear canal.
In many models, the examiner can remove the lens and insert instruments like specialized suction tips through the otoscope into the ear canal, such as for removing earwax. Most models also have an insertion point for a bulb that pushes air through the speculum (pneumatic otoscopy) for testing eardrum mobility.
Types:
Many otoscopes for doctors' offices are wall-mounted, with an electrical cord providing power from an electric outlet. Portable otoscopes powered by batteries (usually rechargeable) in the handle are also available.
Otoscopes are often sold with ophthalmoscopes as a diagnostic set.
Monocular and binocular
Most otoscopes used in emergency rooms, pediatric offices, general practice, and by internists are monocular devices. These provide a two-dimensional view of the ear canal and its contents, and usually at least a portion of the eardrum.
Another method of performing otoscopy (visualization of the ear) is by using a binocular (two-eyed) microscope in conjunction with a larger plastic or metal ear speculum, which provides a much larger field of view. The microscope is suspended from a stand, which frees up both of the examiner's hands; the patient is placed in a supine position and their head is tilted, which keeps the head stable and enables better lighting. The binocular view enables depth perception, which makes removal of earwax or other obstructing materials easier and less hazardous. The microscope also has up to 40× magnification, allowing more detailed viewing of the entire ear canal, and of the entire eardrum (unless prevented by edema of the canal skin). Subtle changes in the anatomy can also be more easily detected and interpreted.
Traditionally, binocular microscopes are only used by otolaryngologists (ear, nose, and throat specialists) and otologists (subspecialty ear doctors). Their widespread adoption in general medicine is hindered by cost and lack of familiarity among pediatric and general medicine professors in physician training programs. Studies have shown that reliance on a monocular otoscope to diagnose ear disease results in a more than 50% chance of misdiagnosis, as compared to binocular microscopic otoscopy.
Pneumatic otoscope
The pneumatic otoscope is used to examine the eardrum for assessing the health of the middle ear. This is done by assessing the eardrum's contour (normal, retracted, full, or bulging), its color (gray, yellow, pink, amber, white, red, or blue), its translucency (translucent, semi-opaque, opaque), and its mobility (normal, increased, decreased, or absent). The pneumatic otoscope is the standard tool used in diagnosing otitis media (infection of the middle ear).
The pneumatic otoscope has a pneumatic (diagnostic) head, which contains a lens, an enclosed light source, and a nipple for attaching a rubber bulb and tubing. By gently squeezing and releasing the bulb in rapid succession, the degree of eardrum mobility in response to positive and negative pressure can be observed. The head is designed so that an airtight chamber is produced when a speculum is attached and fitted snugly into the patient's ear canal. Using a rubber-tipped speculum or adding a small sleeve of rubber tubing at the end of a plastic speculum, can help improve the airtight seal and also help avoid injuring the patient.
By replacing the pneumatic head with a surgical head, the pneumatic otoscope can also be used to clear earwax from the ear canal, and to perform diagnostic tympanocentesis (drainage of fluid from the middle ear) or myringotomy (creation of incision in the eardrum). The surgical head consists of an unenclosed light source and a lens that can swivel over a wide arc.
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See the link here.
Barium
Gist
Barium is a chemical element with the symbol Ba and atomic number 56. It is a soft, silvery-white alkaline earth metal that is highly reactive. Due to its reactivity, it is never found as a free element in nature. Barium is commonly used in diagnostic X-ray procedures (barium swallows and enemas) to visualize the gastrointestinal tract.
Summary
Barium is a chemical element; it has symbol Ba and atomic number 56. It is the fifth element in group 2; and is a soft, silvery alkaline earth metal. Because of its high chemical reactivity, barium is never found in nature as a free element.
The most common minerals of barium are barite (barium sulfate, BaSO4) and witherite (barium carbonate, BaCO3). The name barium originates from the alchemical derivative "baryta" from Greek (barys), meaning 'heavy'. Baric is the adjectival form of barium. Barium was identified as a new element in 1772, but not reduced to a metal until 1808 with the advent of electrolysis.
Barium has few industrial applications. Historically, it was used as a getter for vacuum tubes and in oxide form as the emissive coating on indirectly heated cathodes. It is a component of YBCO (high-temperature superconductors) and electroceramics, and is added to steel and cast iron to reduce the size of carbon grains within the microstructure. Barium compounds are added to fireworks to impart a green color. Barium sulfate is used as an insoluble additive to oil well drilling fluid. In a purer form it is used as X-ray radiocontrast agents for imaging the human gastrointestinal tract. Water-soluble barium compounds are poisonous and have been used as rodenticides.
Details
Barium (Ba), chemical element, one of the alkaline-earth metals of Group 2 (IIa) of the periodic table. The element is used in metallurgy, and its compounds are used in pyrotechnics, petroleum production, and radiology.
Element Properties
atomic number : 56
atomic weight : 137.327
melting point : 727 °C (1,341 °F)
boiling point : 1,805 °C (3,281 °F)
specific gravity: 3.51 (at 20 °C, or 68 °F)
Occurrence, properties, and uses
Barium, which is slightly harder than lead, has a silvery white luster when freshly cut. It readily oxidizes when exposed to air and must be protected from oxygen during storage. In nature it is always found combined with other elements. The Swedish chemist Carl Wilhelm Scheele discovered (1774) a new base (baryta, or barium oxide, BaO) as a minor constituent in pyrolusite, and from that base he prepared some crystals of barium sulfate, which he sent to Johan Gottlieb Gahn, the discoverer of manganese. A month later Gahn found that the mineral barite is also composed of barium sulfate, BaSO4. A particular crystalline form of barite found near Bologna, Italy, in the early 17th century, after being heated strongly with charcoal, glowed for a time after exposure to bright light. The phosphorescence of “Bologna stones” was so unusual that it attracted the attention of many scientists of the day, including Galileo. Only after the electric battery became available could Sir Humphry Davy finally isolate (1808) the element itself by electrolysis.
Barium minerals are dense (e.g., BaSO4, 4.5 grams per cubic centimetre; BaO, 5.7 grams per cubic centimeter), a property that was the source of many of their names and of the name of the element itself (from the Greek barys, “heavy”). Ironically, metallic barium is comparatively light, only 30 percent denser than aluminum. Its cosmic abundance is estimated as 3.7 atoms (on a scale where the abundance of silicon = {10}^{6}
atoms). Barium constitutes about 0.03 percent of Earth’s crust, chiefly as the minerals barite (also called barytes or heavy spar) and witherite. Between six and eight million tons of barite are mined every year, more than half of it in China. Lesser amounts are mined in India, the United States, and Morocco. Commercial production of barium depends upon the electrolysis of fused barium chloride, but the most effective method is the reduction of the oxide by heating with aluminum or silicon in a high vacuum. A mixture of barium monoxide and peroxide can also be used in the reduction. Only a few tons of barium are produced each year.
The metal is used as a getter in electron tubes to perfect the vacuum by combining with final traces of gases, as a deoxidizer in copper refining, and as a constituent in certain alloys. The alloy with nickel readily emits electrons when heated and is used for this reason in electron tubes and in spark plug electrodes. The detection of barium (atomic number 56) after uranium (atomic number 92) had been bombarded by neutrons was the clue that led to the recognition of nuclear fission in 1939.
Naturally occurring barium is a mixture of six stable isotopes: barium-138 (71.7 percent), barium-137 (11.2 percent), barium-136 (7.8 percent), barium-135 (6.6 percent), barium-134 (2.4 percent), and barium-132 (0.10 percent). Barium-130 (0.11 percent) is also naturally occurring but undergoes decay by double electron capture with an extremely long half-life (more than 4 × {10}^{21} years). More than 30 radioactive isotopes of barium are known, with mass numbers ranging from 114 to 153. The isotope with the longest half-life (barium-133, 10.5 years) is used as a gamma-ray reference source.
Additional Information:
Appearance
Barium is a soft, silvery metal that rapidly tarnishes in air and reacts with water.
Uses
Barium is not an extensively used element. Most is used in drilling fluids for oil and gas wells. It is also used in paint and in glassmaking.
All barium compounds are toxic; however, barium sulfate is insoluble and so can be safely swallowed. A suspension of barium sulfate is sometimes given to patients suffering from digestive disorders. This is a ‘barium meal’ or ‘barium enema’. Barium is a heavy element and scatters X-rays, so as it passes through the body the stomach and intestines can be distinguished on an X-ray.
Barium carbonate has been used in the past as a rat poison. Barium nitrate gives fireworks a green colour.
Biological role
Barium has no known biological role, although barium sulfate has been found in one particular type of algae. Barium is toxic, as are its water- or acid-soluble compounds.
Natural abundance
Barium occurs only in combination with other elements. The major ores are barite (barium sulfate) and witherite (barium carbonate). Barium metal can be prepared by electrolysis of molten barium chloride, or by heating barium oxide with aluminium powder.
Classroom Quotes
1. When the Hyderabad Chapter of TFI approached me to be a part of their Leaders in Classroom event, I readily agreed to be a part of it. It was a great classroom experience. I really enjoyed myself. The kids were very expressive and it was heartening to say the least. - Amala Akkineni
2. Everyday classroom teaching is not what children will remember, but how you made a difference in their lives. - Nita Ambani
3. Heroes represent the best of ourselves, respecting that we are human beings. A hero can be anyone from Gandhi to your classroom teacher, anyone who can show courage when faced with a problem. A hero is someone who is willing to help others in his or her best capacity. - Ricky Martin
4. I learned to listen and listen very well. It helped me athletically and in the classroom as well. - Jackie Joyner-Kersee
5. I learned to listen and listen very well. It helped me athletically and in the classroom as well. The person who talks a lot or talks over people misses out because they weren't listening. - Jackie Joyner-Kersee.
Q: What does the dentist of the year get?
A: A little plaque.
* * *
Q: At what time do most people go to the dentist?
A: At tooth-hurty (2:30).
* * *
Q: What does a dentist do on a roller coaster?
A: He braces himself
* * *
Q: What did the dentist say to the computer?
A: This won't hurt a byte.
* * *
Q: What did the dentist see at the North Pole?
A:: A molar bear.
* * *
Q: What was the dentist doing in Panama?
A: Looking for the Root Canal!
* * *
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#10449. What does the term in Biology Astrobiology mean?
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Clay Quotes - II
1. I like having my hands in the clay. I like the movie-making process. -Matthew McConaughey
2. I had a harsh lesson in 1996, when I lost four times to Andres Gomez on clay. - John McEnroe
3. Hard courts are very negative for the body. I know the sport is a business and creating these courts is easier than clay or grass, but I am 100 per cent sure it is wrong. - Rafael Nadal
4. It is very hard for me to switch from clay to grass. - Marat Safin
5. Any quality player can adjust well to the different demands. It is like a good tennis player who is expected to adjust to the clay at the French Open, the grass at Wimbledon, the hard courts of the U.S. and the heat of the Australian Open. A professional is expected to do all that. - Gautam Gambhir
6. Nadal is just more at home on clay. It looks like he feels safer on clay courts. He can get to a few more balls, he can play a bit further behind the baseline when he defends, and he's also able to get the ball to bounce higher. It's unbelievable. - Mats Wilander
7. More than half of the matches are won in the dressing room for him. The guy he's playing against is sitting in the locker-room thinking 'oh my God, I'm going to play Rafa Nadal on clay in five sets, that's going to be painful.' - Mats Wilander
8. I know how to play on clay with confidence if I'm in good shape, and in a good mood and have energy. That's the most important. - Daniil Medvedev.
Q: How many dance teachers does it take to change a light bulb?
A: Five!...Six!...Seven!...Eight!
* * *
Q: How do hens dance?
A: Chick to chick.
* * *
Q: What do they say about dancing vampires?
A: They drag!
* * *
Q: What do you call a dancing lamb?
A: A baa-lerina!
* * *
Q: What kind of dancing might you do in a sink?
A: Tap dancing.
* * *
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