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Материалы IV студенческой конференции «химия. Экология. Медицина» направления работы - страница №19/19

Marie Curie

Salamah Arab Yadam, group 25. Scientific adviser is Tatyana Tishakova.


Chemistry is a vast subject, with numerous notable chemists who demystified the mystical world and made a contribution to the dynamic subject. I'm going to talk about one of my personal favourite great chemists and their contributions.

Marie Curie (1867 - 1934) - She was a Polish born chemist and physicist who later acquired French citizenship. She is prominent for her pioneering research in radioactivity. Her achievements include a theory of radioactivity and the discovery of two radioactive elements; radium and polonium for which she was awarded the Nobel Prize in Chemistry. She died in 1934 from aplastic anemia, a condition caused by overexposure to radiation.

Radiation is widely utilized in modern medicine for therapeutic and diagnostic methods in medicine. It is used for chest X-ray examination and gastric X-ray diagnosis. Also, state-of-the-art nuclear medicine technologies, such as SPECT and PET, are used to diagnose Alzheimer’s disease and cancer. In addition, radiotherapy using X-ray, proton beam, heavy ion beam, and neutron is administered.

A relatively new technique based on the discoveries of Marie Skłodowska-Curie is nuclear medicine which uses substances labeled with radioisotopes introduced into the organs of the patient for imaging of the tumors. Radioactive isotopes of such elements as iodine, indium, or technetium with relatively short half-lives can be used in both diagnosis and therapy. They are being introduced into organs in combination with other substances which selectively bind to various tissues or tissue fluids



Named Reactions In Chemistry

Umm Khaltum Yadam, group 25. Scientific adviser is Tatyana Tishakova.


Many features in science are named after their discoverers, inventors, or founders. This is especially common in chemistry where most elements are named after their discoverers. Reagents, catalysts, and apparatuses are also named after scientists who developed or discovered them. One of the most interesting of this naming system, in chemistry, is the naming of chemical reactions after their developers.

A name reaction is a chemical reaction which is named after its developer or the researcher who discovered it. This process of naming a chemical reaction is rather unorganized compared to the process of naming elements. In the naming of elements, the proposed name for an element has to be approved by the IUPAC committee before it can be recognised. The naming of a name reaction, on the other hand, is rather informal, governed only by unwritten ethical rules, such as follows: the Named reactions have to be useful to many chemists, not just the ones who invented them. The inventors of the reactions may not coin their reactions with their names. This task is meant to be achieved by the literary committee who achieve this feat through publications of textbooks and papers [cenblog]. Sometimes reactions are not named after their inventors, but after the people who contributed to the development of the reaction, for example: The Pinnick oxidation reaction was, originally developed by Lindgren and Nilsson, but the typical reaction condition used today was modified by Kraus even before Pinnick. Chemist H.W. Pinnick, however proved this condition as general and thus earned the tribute of having the reaction named after him [Wiki]. In many cases the naming of a name reaction serves only as a mnemonic rather than a tribute to its developer. Systematic approaches for naming reactions based on the reaction mechanism or the overall transformation exist. However, the more descriptive names are often too difficult to remember or not specific enough. Peoples names are thus used because they are often more practical for efficient communication.

Citation:http://en.wikipedia.org/wiki/Name_reaction; http://cenblog.org/newscripts/2011/08/whats-in-a-name-for-chemists-their-fields-soul/#more-1746

Vladimir Vasilyevich Markovnikov

Amponsah Foster, group 25. Scientific adviser is Tatyana Tishakova.


Markovnikov was borned in December 22 1837 in Knyaginino, Nizhny Novgorod Govenrorate, Russian Empire.he lived for 66years .He attended University of Kazan,University of Saint Petersburg and University of Odessa.He first studied economics and became, after graduation, assistant of Alexander Butlerov in Kazan and Saint Petersburg. After graduation in 1860 he went to Germany for two years where he studied under Richard Erlenmeyer and Hermann Kolbe. He returned to Russia, received his Ph.D in 1869 and succeeded to Butlerov's professorship at Kazan University. After a conflict with that university he was appointed professor at the University of Odessa in 1871, and only two years later at the University of Moscow where he stayed the rest of his career.[ ^ W. Markownikoff (1870). "Ueber die Abhängigkeit der verschiedenen Vertretbarkeit des Radicalwasserstoffs in den isomeren Buttersäuren]

HIS CONTRIBUTION TO MODERN CHEMISTRY,MEDICINE AND PHARMACEUTICAL SCIENCE.; Markovnikov is best known for Markovnikov's rule, elucidated in 1869 to describe addition reactions of H-X to alkenes. According to this rule, the nucleophilic X- adds to the carbon atom with fewer hydrogen atoms, while the proton adds to the carbon atom with more hydrogen atoms bonded to it. Thus, hydrogen chloride (HCl) adds to propene, CH3-CH=CH2 to produce 2-chloropropane CH3CHClCH3 rather than the isomeric 1-chloropropane CH3CH2CH2Cl.[1] The rule is useful in predicting the molecular structures of products of addition reactions. Why hydrogen bromide exhibited both Markovnikov as well as reversed-order, or anti-Markovnikov, addition, however, was not understood until Morris S. Kharasch offered an explanation in 1933.

Hughes has discussed the reasons for Markovnikov's lack of recognition during his lifetime. [2] Although he published mostly in Russian which was not understood by most Western European chemists, the 1870 article in which he first stated his rule was written in German. However the rule was included in a 4-page addendum to a 26-page article on isomeric butyric acids, and based on very slight experimental evidence even by the standards of the time. Hughes concludes that the rule was an inspired guess, unjustified by the evidence of the time, but which turned out later to be correct (in most cases).[ Hughes, Peter (2006). "Was Markovnikov's Rule an Inspired Guess?". The Journal of Chemical Education]

Markovnikov also contributed to organic chemistry by finding carbon rings with more than six carbon atoms, a ring with four carbon atoms in 1879, and a ring with seven in 1889.Markovnikov also showed that butyric and isobutyric acids have the same chemical formula (C4H8O2) but different structures; i.e., they are isomers. [Hughes, Peter (2006). "Was Markovnikov's Rule an Inspired Guess?". The Journal of Chemical Education].



Friedrich Christian Accum

Akwei Nii Adotey, group 25. Scientific adviser is Tatyana Tishakova.

Friedrich Christian Accum or Frederick Accum (March 29, 1769 – June 28, 1838) was a German chemist, whose most important achievements included advances in the field of gas lighting, efforts to keep processed foods free from dangerous additives, and the promotion of interest in the science of chemistry to the general populace.[1] From 1793 to 1821 Accum lived in London. Following an apprenticeship as an apothecary, he opened his own commercial laboratory enterprise. His business manufactured and sold a variety of chemicals and laboratory equipment. Accum, himself, gave fee based public lectures in practical chemistry and collaborated with research efforts at numerous other institutes of science

Intrigued by the work of Frederick Winsor, who had been championing the introduction of gas lighting in London, Accum too, became fascinated by this innovation. At the request of the Gas Light and Coke Company, he carried out many experiments in this novel field of inquiry. After a time of close working association with this company, he became a member of its board of directors in 1812. The company was charged with founding the first gasworks in London to supply gas lighting to both private and public areas. Accum was instrumental in the conception and design of this extremely successful gasworks.

The majority of Accum's publications were written in English. They were executed in a style that made them quite accessible to the common man. Many scientific contributions were brought forth through his writings, which were influential in the popularization of chemistry during this era. In 1820, Accum published Treatise on Adulteration of Food, in which he denounced the use of chemical additives to food. This ground breaking work marked the beginning of an awareness of need for food safety oversight. Accum was the first person to tackle the subject and to reach a wide audience through his activities. His book, controversial at the time, found a wide audience and sold well. However, it threatened established practices within the food processing industry, earning him many enemies among the London food manufactures. Accum left England after a lawsuit was brought against him. He lived out the rest of his life as a teacher at an industrial institution in Berlin.




WITTIG REACTIONS




Oluwaseyifunmi Oluwadurotimi Onabolu, group 25. Scientific adviser is Tatyana Tishakova.


The Wittig reaction or Wittig Olefination is a chemical reaction of an aldehyde or ketonewith a triphenyl phosphonium ylide (often called a Wittig reagent) to give an alkene and triphenylphosphine oxide.

The Wittig reaction was discovered in 1954 by Georg Wittig, for which he was awarded the Nobel in 1979. It is widely used in organic synthesis for the preparation of alkenes. It should not be confused with the Wittig rearrangement.

Wittig reactions are most commonly used to couple aldehydes and ketones to singly substituted phosphine ylides. With simple ylides this results in almost exclusively the Z-alkene product. In order to obtain the E-alkene, the Schlosser modification of the Wittig reaction can be performed.

His steric bulk of the ylide 1 influences the stereochemical outcome of nucleophilic addition to give a predominance of the betaine 3(c.f. Bürgi–Dunitz angle). Note that for betaine 3 both R1 and R2 as well as PPh3+ and O- are positioned anti (trans-diaxial) to one another.

Carbon-carbon bond rotation gives the betaine 4, which then forms the oxaphosphetane 5. Elimination gives the desired Z-alkene 7 and triphenylphosphine oxide 6. With simple Wittig reagents, the first step occurs easily with both aldehydes and ketones, and the decomposition of the betaine (to form 5) is the rate-determining step. However with stabilised ylides (where R1 stabilises the negative charge) the first step is the slowest step, so the overall rate of alkene formation decreases and a bigger proportion of the alkene product is the E-isomer. This also explains why stabilised reagents fail to react well with sterically hindered ketones.

References: [Wikipedia, the free encyclopedia.] [Organic chemistry portal.]



George Porter

Precious Chidumga, Madukwe, group 25. Scientific adviser is Tatyana Tishakova.


George Hornidge Porter, Baron Porter of Luddenham, OM, FRS(6 December 1920 – 31 August 2002) was a British chemist.His original research in developing the technique of flash photolysis to obtain information on short-lived molecular species provided the first evidence of free radicals.He was awarded the Nobel Prize in Chemistry in 1967 along with Manfred Eigen and Ronald George Wreyford Norrish.[1]

Flash photolysis is a pump-probe laboratory technique, in which a sample is firstly excited by a strong pulse (called pump pulse) of light from a laser of nanosecond, picosecond, or femtosecond pulse width or by a short-pulse light source such as a flash lamp. Flash photolysis was developed shortly after World War II as a result of the military's attempts to build cameras fast enough to photograph missiles in flight. The interest in flash photolysis grew considerably as the practical applications expanded from chemistry to areas such as biology, materials science, and environmental sciences. Today flash photolysis facilities are extensively used by researchers to:



  • study light-induced processes in organic molecules, polymers, nanoparticles, semiconductors,

  • studyphotosynthesis in plants, signaling, and light-induced conformational changes in biological systems.[2]

References

1."George Porter – Biography". Nobel Media. Retrieved 30 April 2011.

2. Wikipedia.com

Antoine-Laurent Lavoisier

Precious Ochegba Adejo, group 25. Scientific adviser is Tatyana Tishakova.


Antoine-Laurent Lavoisier (1743-1794)

  • He changed Chemistry from a qualitative to a quantitative science by freeing them from the disillusionment of the phlogiston theory and introducing that the mass of products in a reaction is equal to the mass of reactants. This was also known as the Law of Conservation of Mass

  • He demonstrated the role of oxygen in rusting a metal as well as its role in plant and animal respiration showing that respiration was a slow combustion of organic material using inhaled oxygen.

  • Lavoisier discovered that Henry Cavendish’s ‘inflammable air,’ which Lavoisier had termed hydrogen combined with oxygen to produce a dew which appeared to be water.

  • He showed that oxygen is consumed and carbon-dioxide given off during respiration

  • Lavoisier investigated the composition of water and air which were considered elements and found that water was a composition of hydrogen and oxygen and air was a mixture of gases primarily oxygen and nitrogen

  • With Laplace another scientist, Lavoisier used the calorimeter to measure heat evolved per unit carbon dioxide produced. They found the same ratio for a flame and animals, indicating that animals produced energy by a type of combustion.

REFERENCES

[1] Wikipedia Free Online Encyclopedia

[2] www.antoine-lavoisier.com

[3] World of Scientific Bibliography www.scienceworld.wolfram.com



Carl Ferdinand Cori (1896–1984) and Gerty Theresa Cori

(1896–1957)

Emmanuel Timilehin, group 25. Scientific adviser is Tatyana Tishakova.


Animals, including humans, are constantly on the go. Where do they get the energy? A husband- and-wife team, Carl Ferdinand Cori (1896–1984) and Gerty Theresa Cori (1896–1957), identified the cyclical process that muscle cells use to make and store energy. Understanding this process of sugar metabolism called the Cori cycle is particularly important for treating diabetes, a condition where the cycle is disrupted. [1]

The Coris were great scientific collaborators, and their collaborations in biochemistry ultimately won them the 1947 Nobel Prize in physiology or medicine, making Gerty the first American woman to win a Nobel Prize. The two spent their lives researching carbohydrates and the chemical reactions that the body uses to break down certain carbohydrates and synthesize others. They were especially interested in the class of carbohydrates known as sugars. Among other remarkable feats, they discovered “the Cori ester,” a breakdown product of glycogen (the form in which sugar is stored in muscles), and they were able to reverse this reaction in a test tube, forming glycogen again. [2]



REFERENCE

  1. Carl and Gerti Cori and Carbohydrate Metabolism". American Chemical Society.

Retrieved June 6, 2012

  1. Larner, Joseph (1992). "Gerty Theresa Cori". National Academy of Sciences. pp. 113,

124, 125. Retrieved 17 June 2010.

NAMED REACTIONS IN CHEMISTRY

Chioma Annastasia Obi, group 26. Scientific adviser is Evgeniya Grabovetskaya.


Baeyer-Villiger oxidation

[1] Baeyer, A.; Villiger, V. Ber., 1899, 24, 3625.

[2] Baeyer, A.; Villiger, V. Ber., 1900, 33, 858.

[3] House, H.O. Modern Synthetic Reactions, 2nd Ed. 1972,, Benjamin; Menlo Park, CA., pp. 306-307, 321-328.

EXAMPLE: [1]Wiberg, K.B.;* Snoonian, J.R. J. Org. Chem., 1998, 63, 1390-1401.

[2] Burton, J.W.; Clark, J.S.; Derrer, S.; Stork, T.C.; Bendall, J.G.; Holmes, A.B. J. Am. Chem. Soc.,1997, 119, 7483-7498.



Barbier reaction

[1] Barbier, P. Compt. Rend., 1899, 128, 110.

[2] The original Barbier reaction combined a ketone, magnesium metal, and an alkyl halide in situ to give a substituted alcohol product. 

EXAMPLE: Zhou, J-Y.; Jia, Y.; Sun, G-F.; Wu, S-H.* Synth. Commun., 1997, 27, 1899-1906.

Barton-McCombiedeoxygenation

[1] Barton, D.H.R.; McCombie, S.W. J. Chem. Soc., Perkin Trans. I, 1975, 1574-1585.

[2]Robins, M.J.; Wilson, J.S.; Hansske, F. J. Am. Chem. Soc., 1983, 105, 4059-4065.

EXAMPLE: [1] Lopez, R.M.; Hays, D.S.; Fu, G.C.* J. Am. Chem. Soc., 1997, 119, 6949-6950.

 

[2] Lee, E.;* Yoon, C.H. J. Chem. Soc., Chem. Commun., 1994, 479-481.




John Dalton

Adogba Oluwabusola Fausat, group 26. Scientific adviser is Evgeniya Grabovetskaya.


Best-known for his work in modern atomic theory, John Dalton was an English chemist, meteorologist and physicist. The son of a weaver, Dalton's major contribution to the field of chemistry is his atomic theory proposed in 1803. In the theory he reasoned that tiny particles called atoms make up elements.
Early beginnings

Though he came from a family of shoemakers and weavers, Dalton earned his living as a lecturer. Even at a young age he was interested in metrology and would spend time learning how to use metrological instruments and taking periodic readings. In fact, it was Dalton's work in this field that turned what was considered by many to be folklore into a respectable science.

Dalton's atomic theory

In his famous atomic theory, Dalton stated that tiny particles called atoms form elements. Different elements would have atoms of different sizes and mass. According to him atoms were unique, as they couldn't be created, divided or destroyed by chemical process. The later discovery of nuclear fusion and nuclear fission altered this viewpoint, though these were nuclear and not chemical reactions. The discovery of isotopes subsequently proved that elements can be identical in chemical structure but different in weight.

Understanding the atom

Atoms of a same element are always identical. He went on to prove that atoms of different elements could be differentiated by their atomic number. Atoms of different elements combine to form compounds. Compounds are unique, having a specific relative number of atoms. Dalton's theory was the important first step towards modern atomic theory.

The colourful truth about colour blindness

Dalton's theory on colour-blindness was one of the first researches published. Being the first person to research this, colour-blindness was known as Daltonism. He had made this important discovery when he realised that his own brother was colour-blind. Though his theory; that colour perception was by the discolouration of the liquid medium in the eyeball was disproved during his lifetime, it was the first time that this problem was formally discussed. John Dalton also held the view the atmosphere was a mixture of gasses. He believed the main ingredients were a mixture of 80% nitrogen and 20% oxygen.


Antoine Lavoisier

Onuchukwu Chibuzor Victor, group 26. Scientific adviser is Evgeniya Grabovetskaya.


Beginning in 1775, he served in the Royal Gunpowder Administration, where his work led to improvements in the production of gunpowder and the use of agricultural chemistry by designing a new method for preparing saltpeter.

Antoine Lavoisier - Research on hydrogen and role disproving Phlogiston theory

He also discovered that the inflammable air of Henry Cavendish which he termed hydrogen (Greek for "water-former"), combined with oxygen to produce a dew, as Joseph Priestley had reported, which appeared to be water. Lavoisier's work was partly based on the work of Priestley (he corresponded with Priestley and fellow members of the Lunar Society). In Sur la combustion en general (On Combustion in general, 1777) and ConsidérationsGénéralessur la Nature des Acides (General Considerations on the Nature of Acids), 1778), he demonstrated that the "air" responsible for combustion was also the source of acidity. In 1779, he named this part of the airoxygen (Greek for "acid-former"), and the other azote (Greek for "no life"). In Reflexionssur le Phlogistique (Reflections on Phlogiston, 1783), Lavoisier showed the phlogiston theory to be inconsistent.



Antoine Lavoisier - Pioneer of Stoichiometry

Lavoisier's experiments were among the first truly quantitative chemical experiments ever performed; that is, he carefully weighed the reactants and products involved. He showed that, although matter changes its state in a chemical reaction, the quantity of matter is the same at the end as at the beginning of every chemical reaction( Conservation law). He burnt phosphorus and sulfur in air, and proved that the products weighed more than the original.



Antoine Lavoisier - Major works on analytical chemistry and chemical nomenclature

Lavoisier also investigated the composition of water and air, which at the time were considered elements. He discovered the components of water were oxygen and hydrogen, and that air was a mixture of gases - primarily nitrogen and oxygen. With the French chemists Claude-Louis Berthollet, Antoine Fourcroy and Guyton de Morveau, Lavoisier devised a chemical nomenclature, or a system of names describing the structure of chemical compounds. He described it inMéthode de nomenclature chimique (Method of Chemical Nomenclature, 1787). Their system facilitated communication of discoveries between chemists of different backgrounds and is still largely in use today, including names such as sulfuric acid, sulfates, and sulfites.

His TraitéÉlémentaire de Chimie (Elementary Treatise of Chemistry, 1789, translated into English by Robert Kerr) is considered to be the first modern chemical textbook, and presented a unified view of new theories of chemistry, contained a clear statement of the Law of Conservation of Mass, and denied the existence of phlogiston. Also, Lavoisier clarified the concept of an element as a simple substance that could not be broken down by any known method of chemical analysis, and he devised a theory of the formation of chemical compounds from elements.His contributions are considered the most important in advancing the science of chemistry to the level of what had been achieved in physics and mathematics during 18th century.
Joseph Priestley

Adanma Duru, group 26. Scientific adviser is Evgeniya Grabovetskaya.


Ever had a sip of soda and marvelled at the fact how a little fizz makes it different from fruit juices? Joseph Priestley added fizz in our life with the discovery of soda water and oxygen.
Today everyone knows oxygen is essential for us to breathe. People, animals and plants all need this gas to live. Joseph Priestley was the first person to discover oxygen.  He also invented soda water, the substance that makes soft drinks so fizzy.

An electrifying discovery

Documenting the history of electricity was Priestley’s first scientific work. He met many famous experimenters including John Canton, William Watson and Benjamin Franklin.  He became so interested that he started his own experiments in electricity. Priestley discovered certain substances like charcoal that conducted electricity. This changed the belief that only water and liquids were good conductors of electricity. His book on the history of electricity became standard for over a century.

Soda water

When James Cook was to set sail on his second South Sea voyage, Joseph Priestley showed sailors how to create soda water. He thought this would cure Scurvy - a disease caused by lack of Vitamin C, common in sailors. Priestley discovered how to infuse water with carbon dioxide by suspending a bowl of water over a beer vat. He later experimented how to create carbon dioxide gas and infuse it in agitated water.

Experiments on airs and the discovery of oxygen

In 1744, Priestley conducted experiments on isolating air and discovered a new gas. Originally called dephlogisticated air, it was later named oxygen. He produced this by focusing suns rays on mercuric oxide. The reaction that resulted produced oxygen. Priestley’s experiments in air also lead to several discoveries, including nitric oxide, anhydrous hydrochloric acid, ammonia and nitrous oxide.

Studies in photosynthesis

Priestley’s studies and experiments in air also lead to the first discovery of photosynthesis. He showed how a burning candle in an inverted jar used up air and how keeping a plant in that jar could then produces oxygen by photosynthesis.

Mitsunobu Reaction

Oiseremen Samuel Ovbiagele, group 26. Scientific adviser is Evgeniya Grabovetskaya.


A name reaction is a chemical reaction named after its discoverers or developers. Well known examples include the Wittigreaction, the Claisencondensation, the Friedel-Craftsacylation, and the Diels-Alderreaction. Am going to take intomitsunobu reaction for this project.

Mitsunobu Reaction:The Mitsunobu Reaction allows the conversion of primary and secondary alcohols to esters, phenyl ethers, thioethers and various other compounds. The nucleophile employed should be acidic, since one of the reagents (dead, diethylazodicarboxylate) must be protonated during the course of the reaction to prevent from side reactions.

Mechanism of the Mitsunobu Reaction


The triphenylphosphine combines with DEAD to generate a phosphonium intermediate that binds to the alcohol oxygen, activating it as a leaving group. Substitution by the carboxylate, mercaptyl, or other nucleophile completes the process.

The reaction proceeds with clean inversion, which makes the Mitsunobu Reaction with secondary alcohols a powerful method for the inversion of stereogenic centers in natural product synthesis.Side Reaction:



New protocols have been developed which allow better removal of side products and/or the conversion of more basic nucleophiles.



Marie Curie

Faust Adogba, group 26. Scientific adviser is Evgeniya Grabovetskaya.


Today, we talk about radioactivity and radioactive elements. But do you know who coined the term 'radioactivity''? Yes, it was the Nobel Prize winning Marie Curie. She discovered two important elements - Radium and Polonium, which you will be able to easily spot in the periodic table.

Marie Curie was born as Maria Sklodowska in Warsaw, Poland in 1867. Growing up in poverty, she moved to Paris to study further, and subsequently obtained her higher degrees there[1]. Curie and her husband Pierre Curie performed their early researches under difficult conditions. Lab arrangements were poor and they had to take up teaching to feed themselves[2].

Marie Curie's hard work finally paid off when she isolated Polonium from its compound. She named it after her country of birth, Poland[1]. She then successfully developed methods to separate Radium from its radioactive residues. Marie Curie deserves credit for two things. For discovering two unique elements Polonium and Radium and then finding properties in these elements that will benefit the world[2].

Curie was the first woman to be awarded the Nobel Prize. In fact, she was the first person to win two Nobel Prizes. One for chemistry for the discovery of Radium and Polonium, and one for physics for her work on radiation phenomenon. She was also the first female professor at the University of Paris[1][2].

Due to her constant research work on radioactive elements, she was exposed to dangerous levels of radiation. On 4th July, 1934 Marie Curie died of Aplastic Anemia[1]. Her documents and work are too dangerous to handle due to their high levels of radioactivity. Thus, they can be physically accessed only with protective clothing[2].

References

[1] "Marie Curie - Biography". Nobelprize.org. 4 July 1934. Retrieved 1 August 2012.

[2]  Robert William Reid (1974). Marie Curie. New American Library. p. 12. ISBN 0002115395. Retrieved 2 August 2012.

MINERALS ARE EARTS TREASURES

Sekar Shabari Venkat, group 30. Scientific adviser is Evgeniya Grabovetskaya.


A mineral is a naturally occurring substance that is solid and stable at room temperature, representable by a chemical formula, usually abiogenic, and has an ordered atomic structure. It is different from a rock, which can be an aggregate of minerals or non-minerals, and does not have a specific chemical composition. The exact definition of a mineral is under debate, especially with respect to the requirement a valid species be abiogenic, and to a lesser extent with regards to it having an ordered atomic structure. The study of minerals is called mineralogy.

There are over 4,900 known mineral species; over 4,660 of these have been approved by theInternational Mineralogical Association (IMA). The silicate minerals compose over 90% of theEarth's crust. The diversity and abundance of mineral species is controlled by the Earth's chemistry. Silicon and oxygen constitute approximately 75% of the Earth's crust, which translates directly into the predominance of silicate minerals. Minerals are distinguished by various chemical and physical properties. Differences in chemical composition and crystal structure distinguish various species, and these properties in turn are influenced by the mineral's geological environment of formation.

The first criterion means that a mineral has to form by a natural process, which excludes anthropogenic compounds. Stability at room temperature, in the simplest sense, is synonymous to the mineral being solid. More specifically, a compound has to be stable or metastable at 25°C. Classical examples of exceptions to this rule include native mercury, which crystallizes at −39°C, and water ice, which is solid only below 0°C; as these two minerals were described prior to 1959, they were grandfathered by the International Mineralogical Association (IMA).[2][3] Modern advances have included extensive study of liquid crystals, which also extensively involve mineralogy. Minerals are chemical compounds, and as such they can be described by fixed or a variable formula. Many mineral groups and species are composed of a solid solution; pure substances are not usually found because of contamination or chemical substitution. For example, the olivine group is described by the variable formula (Mg, Fe)2SiO4, which is a solid solution of two end-member species, magnesium-rich forsterite and iron-rich fayalite, which are described by a fixed chemical formula. Mineral species themselves could have a variable compositions, such as the sulfidemackinawite, (Fe, Ni)9S8, which is mostly a ferrous sulfide, but has a very significant nickel impurity that is reflected in its formula.[1][4]

Minerals are not equivalent to rocks. Whereas a mineral is a naturally occurring usually solid substance, stable at room temperature, representable by a chemical formula, usually abiogenic, and has an ordered atomic structure, a rock is either an aggregate of one or more minerals, or not composed of minerals at all.[27] Rocks like limestone or quartzite are composed primarily of one mineral—calcite or aragonite in the case of limestone, and quartz in the latter case.[28][29] Other rocks can be defined by relative abundances of key (essential) minerals; a granite is defined by proportions of quartz, alkali feldspar, and plagioclase feldspar.[30] The other minerals in the rock are termed accessory, and do not greatly affect the bulk composition of the rock. Rocks can also be composed entirely of non-mineral material; coal is a sedimentary rock composed primarily of organically derived carbon.[27][31]

In rocks, some mineral species and groups are much more abundant than others; these are termed the rock-forming minerals. The major examples of these are quartz, the feldspars, the micas, theamphiboles, the pyroxenes, the olivines, and calcite; except the last one, all of the minerals are silicates.[32] Overall, around 150 minerals are considered particularly important, whether in terms of their abundance or aesthetic value in terms of collecting.[33]

REFERENCES:

[1] Dyar and Gunter, pp. 2–4

[2] "Mercury". Mindat.org. Retrieved 2012-08-13.

[3] Mindat.org. Retrieved 2012-08-13.

[4] "Mackinawite". Mindat.org. Retrieved 2012-08-13.

[5]  Chesterman and Lowe, pp. 13–14



THE CONTRIBUTION OF GREAT CHEMISTS TO THE DEVELOPMENT OF MODERN CHEMISTRY, MEDICINE AND PHARMACEUTICAL SCIENCE

Noeline Wesley, group 34. Scientific adviser is Svetlana Nakonechnaya.


Jabir bin Hayyan (721-815), Persia (some say Arab others say Persian race) was a prominent polymath and considered the father of modern chemistry. He invented of over twenty types of now-basic chemical laboratory equipment, such as the alembic and retort.
He discovered sulfuric acid, and by distilling it together with various salts, Jabir discovered hydrochloric acid (from salt) and nitric acid (from saltpeter).

John Dalton (1766-1844) Started as a lecturer, Sir John Dalton is one of the most famous chemists. His achievements include discovery of atoms, development of John Dalton's atomic theory and color blindness findings. He postulated that elements are made up of small atoms, which can neither be created nor destroyed. In his theory, it was mentioned that atoms of an element are similar to each other, but they differ from those of other elements.English chemist and physicist. His theory (1805) accounts for the law of conservation of mass, law of definite proportions, and law of multiple proportions, he also reduced the first table of atomic weights



Alfred Nobel (1833-1896), Swedish chemist, engineer, best known for isolating dynamite
Luis Federico Leloir (1906-1987), Argentine biochemist and winner of the 1970 Nobel Prize for research into sugar nucleotides, metabolism of carbohydrates, and renal hypertension
TeunisVen-der Linden (1884-1965), Dutch chemist, developed insecticide "Lindane"
Democritus (460-370B.C.), Greek philosopher introduced idea that matter consisted of atoms having physical size and shape which constantly moved in a void and interacted in different ways
Daniel Rutherford (1749-1819), discovered nitrogen
Robert Boyle (1627-1691), English physicist and chemist. Experimented in pneumatics (thestudy of mechanical properties of air and other gases). Through research he rejected the accepted definition of matter and Proposed Boyle's Law (1662)
Henry Canvendish (1731-1810), English physicist and chemist, discovered hydrogen (1766), and discovered nitric acid
John Dalton (1766-1844), English chemist and physicist,(1793), developed atomic theory. His theory (1805) accounts for the law of conservation of mass, law of definite proportions, and law of multiple proportions, he also reduced the first table of atomic weights
Amedeo Avogadro (1776-1856) stated that equal volumes of gases, at the same temperature and pressure, had the same amount of molecules, Avogadros number is 6.022e23, meaning that exactly 12 grams of carbon 12 has exactly 6.022e23 carbon atoms
Joseph Louis Gay-Lussac (1778-1850), French chemist and physicist, developed the law of volumes concerning the combination of gases, and also discovered Boron
Robert Wilhelm Bunsen (1811-1899), German chemist, helped develop the spectroscope, introduced the Bunsen burner that was actually developed by his laboratory assistant, Peter Desaga, discovered elements Cesium and Rubidium
Dmitri Ivanovich Mendeleev (1834-1907), Russian chemist, Developed the periodic table by placing the elements in order of increasing atomic weight (1869), Predicted the existence and properties of elements that would fill the gaps left in his chart (1871), These elements were discovered between 1875 and 1885.


IRON

Noeline Wesley, group 34. Scientific adviser is Svetlana Nakonechnaya.


Iron is abundant in biology. Iron-proteins are found in all living organisms, ranging from the evolutionarily primitive archaea to humans. The color of blood is due to the hemoglobin, an iron-containing protein. As illustrated by hemoglobin, iron often is bound to cofactors, e.g. in hemes. The iron-sulfur clusters are pervasive and include nitrogenase, the enzymes responsible for biological nitrogen fixation. Influential theories of evolution have invoked a role for iron sulfides, iron-sulfur world theory.

Iron is a necessary trace element found in nearly all living organisms. Iron-containing enzymes and proteins, often containing heme prosthetic groups, participate in many biological oxidations and in transport. Examples of proteins found in higher organisms include hemoglobin, cytochrome (see high-valent iron), and catalase.

The most important use of iron supplements is to treat iron deficiency anemia. Anemia is low levels of iron in the blood. Iron is important because it is a key component of hemoglobin, which carries oxygen to the entire body. Anemia can be caused by many conditions, including loss of blood during heavy menstruation, pregnancy, blood donation, bleeding ulcers, and surgery

NITROGEN

Gunanesan James Alexsanth, group 34. Scientific adviser is Svetlana Nakonechnaya.


Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere. The element nitrogen was discovered as a separable component of air, by Scottish physician Daniel Rutherford, in 1772.

Many industrially important compounds, such as ammonia, nitric acid, organic nitrates (propellants and explosives), and cyanides, contain nitrogen. The extremely strong bond in elemental nitrogen dominates nitrogen chemistry, causing difficulty for both organisms and industry in breaking the bond to convert the N2 into useful compounds, but at the same time causing release of large amounts of often useful energy when the compounds burn, explode, or decay back into nitrogen gas.

Nitrogen occurs in all living organisms, and the nitrogen cycle describes movement of the element from the air into the biosphere and organic compounds, then back into the atmosphere. Synthetically produced nitrates are key ingredients of industrial fertilizers, and also key pollutants in causing the eutrophication of water systems. Nitrogen is a constituent element of amino acids and thus of proteins  and nucleic acids (DNA and RNA). It resides in the chemical structure of almost all neurotransmitters, and is a defining component of alkaloids, biological molecules produced by many organisms. The human body contains about 3% by weight of nitrogen, a larger fraction than all elements save oxygen, carbon, and hydrogen.

The contribution of great chemists to the development of modern chemistry, medicine and pharmaceutical science

Ndongotou Diema, group 1ST dentistry. Scientific adviser is Svetlana Kozub.


The development in chemistry

Chemistry was a huge quantitative progress with Antoine Lavoisier, who was promoted to the rank of an exact science. His Elements of Chemistry (1789) is considered the first modern chemical textbook, this book contains a list of items or substances that can not be decomposed further, including oxygen, nitrogen, hydrogen, phosphorus, mercury, zinc and sulfur. Antoine Lavoisier is considered the father of modern chemistry.

It was during the nineteenth century, the chemistry really took off: Dalton atomic theory, gas laws, Avogadro's hypothesis, calculation of atomic weights, birth of organic chemistry, valence theory, structural chemistry and ordering of the elements with the Mendeleyev periodic Table. At the end of the century, physics and chemistry contribute to the discovery of radioactivity.

It is the discovery of X-rays (1895), and the radioactivity by Henri Becquerel in 1896 and his work with Pierre and Marie Curie in 1898 that helped to begin to understand the structure of atoms.



The development in medicine

Medicine has experienced a revolution from the nineteenth century because of advances in chemistry and laboratory techniques. The old concepts of epidemiology of infectious diseases have been supplanted by the emergence of bacteriology and virology.

After the publication in 1859 of Charles Darwin's Origin of Species, Gregor Mendel (1822-1884) published in 1865 his books on the transmission of genetic traits peas, discoveries that will later known under the name of Mendel's Laws .Semmelweis's work have been strengthened by the discoveries of Louis Pasteur. By establishing a link between the disease and the microorganisms, Pasteur brought about a revolution in medicine. He also invented with Claude Bernard (1813-1878) the process of pasteurization still in use today. The participation of women in health care (outside of the role of midwives, assistants and housekeepers) was initiated by people like Florence Nightingale. In a profession previously dominated by men, women have played a role in nursing in order to reduce the mortality of patients due to poor hygiene and a lack of nutrition. Nightingale set up the St Thomas' Hospital, after the Crimean War in 1852. Elizabeth Blackwell was the first woman to study and then to practice medicine in the United States.

Development modern in pharmacy:

In 1888: Dr. Wallace C. Abbott, a physicist begins totabletingdosimetric that incorporate active ingredients, but at extremely low doses rigorous, eicaces the treatments available at the time. This is one of the founders of modern pharmacy.

Sir Alexander Fleming is a British biologist and pharmacologist, born August 6, 1881 at Lochfield, Ayrshire, Scotland and died March 11, 1955 in London. He has published many articles on bacteriology, immunology and chemotherapy. His best-known discoveries are those of the enzyme lysozyme in 1922 and the antibiotic substance penicillin he called isolated from the fungus Penicilliumnotatum in 1928, for which discovery he shared the Nobel Prize in Physiology or Medicine Howard Walter Florey and with Ernst Boris Chain in 1945

Paul EhrlichIn 1909, Bayer student derivatives of atoxylBéchamp, he develops an arsenical active against syphilis, arsphenamine, or 606, the first truly effective synthetic drug it markets under the name Salvarsan and that it improves thereafter Néosalvarsan2. Isolated in the early 1920s, the active element arsphenamine will be developed in 1936 by Tatum and Cooper and marketed under the name Mapharsen. He will be replaced in 1945 by penicillin. The discovery of Salvarsan is Paul Ehrlich to be regarded by many as the "father of chemotherapy".


Відповідальні за випуск: Козуб С.М., Наконечна С.А., Тішакова Т.С.



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