Selenium - Selenium Arsenic - Selenium - Bromine S Se Te Full table General Name, Symbol, Number Selenium, Se, 34 Series Nonmetals Group, Period, Block 16 (VIA), 4 , p Density, Hardness 4790 kg/m3(300K), 2 Appearance grey, metallic lustre Atomic Properties Atomic weight 78.96 amu Atomic radius (calc.) 115 (103) pm Covalent radius 116 pm van der Waals radius 190 pm Electron configuration [Ar]3d3d104p44s2 e- 's per energy level 2, 8, 18, 6 Oxidation states (Oxide) ±2,4,6 (strong acid) Crystal structure Hexagonal Physical Properties State of matter solid (__) Melting point 494 K (430 °F) Boiling point 957.8 K (1265 °F) Molar volume 16.42 ×1010-3 m3/mol Heat of vaporization 26.3 kJ/mol Heat of fusion 6.694 kJ/mol Vapor pressure 0.695 Pa at 494 K Speed of sound.
Jöns Jacob Berzelius - of the fathers of modern chemistry (along with John Dalton and Antoine Lavoisier). Berzelius discovered the elements silicon, selenium, thorium, and cerium. He was inducted into the Royal Swedish Academy of Sciences in 1808, and became a member of the Swedish Academy in 1837. Trained as a medical doctor at the Uppsala University, in 1807 he became a professor at the Stockholm University. Not long after arriving there he wrote a chemistry textbook for his medical students, from which point a long and fruitful career in chemistry began. While conducting experiments in support of the textbook he discovered the law of constant proportions, which showed that inorganic substances are composed of different elements in constant proportions by weight. From this, by 1828 he compiled a table of the relative atomic weights.
I, Robot - first paragraph is a quotation of one of the book's characters, Dr Susan Calvin, but the rest reads rather like the copy of an editor who hadn't actually read the book. At the time of publication, robots were depicted in science fiction as either servile machines or evil creations that revolted in the manner of Frankenstein. Asimov himself said that in writing the Robot stories he sought to replace both views with something more rational. Warning: Wikipedia contains spoilers Robbie This first story in the collection is basically about the technophobia that surrounds robots, and how it is misplaced. This is not such a strange place to start, when you see that almost every science fiction story to feature a robot up until publication of this one was of the 'robot.
Instamatic - more basic Instamatic 50, without no built-in flash, had been released in the UK a couple of weeks earlier. A few of other models soon followed, including the 400 which featured a clockwork automatic film advance and automatic exposure bsaed on a selenium light meter, and the aluminum chassis 800 with rangefiner based focus in addition to clockwork winding and light meter. The Instamatic was an instant success; more than 50 million Instamatic cameras were produced between 1963 and 1970. In 1965 came the four exposure flash cubess, the cameras so equipped identifiable by 4 being added to the model number (the 100 became the 104 etc.). The Magicube came in 1970, each bulb featuring a mechanically triggered pyrotechnic detonator, thus avoiding the requirement for batteries. Models equipped for these cubes.
Heat of vaporization - 37 Element Heat of vaporization (kJ/mol) Radon 16.4 Rhenium 715 Rhodium 493 Rubidium 72.216 Ruthenium 595 Scandium 314.2 Selenium 26.3 Silicon 384.22 Silver 250.58 Sodium 96.96 Strontium 144 Sulfur 1.7175 Tantalum 743 Technetium 660 Tellurium 52.55 Thallium 164.1 Thorium 514.4 Tin 295.8 Titanium 421 Tungsten 824 Vanadium 452 Xenon 12.636 Yttrium 363 Zinc 115.3 Zirconium 58.2 .
Hydride - covalently bonded to more electronegative p-block (boron, aluminium and Group 4-7) elements and beryllium. Common compounds including hydrocarbons, ammonia and hydrazine could be considered as hydrides of carbon and nitrogen but the term is only used for collectively naming all hydrogen compounds of an element. Ammonia is never called nitrogen trihydride. The hydride nomenclature does not suffice to provide a unique name for each hydrocarbon. Choice of nomenclature, either as metal hydrides or in parallel to alkane, alkene and alkyne, mostly depends on the perspective of the scientist. Covalent hydrides behave as molecules with the weak London forces and hence are volatile at room temperature and atmospheric pressure. Aluminum and beryllium hydrides are polymeric because of three center bond. Properties of covalent hydrides vary individually. The following is a list of.
Ultramarine - up for by addition of the calculated weight of finely divided silica); (2) anhydrous sulphate of soda; (3) anhydrous carbonate of soda; (4) sulphur (in the state of powder); and (5) powdered charcoal or relatively ash-free coal, or colophony in lumps. "Ultramarine poor in silica" is obtained by fusing a mixture of soft clay, sodium sulphate, charcoal, soda and sulphur. The product is at first white, but soon turns green ("green ultramarine") when it is mixed with sulphur and heated. The sulphur fires, and a fine blue pigment is obtained. "Ultramarine rich in silica" is generally obtained by heating a mixture of pure clay, very fine white sand, sulphur and charcoal in a muffle-furnace. A blue product is obtained at once, but a red tinge often results. The different ultramarines—green, blue,.
Glutathione peroxidase - glutathione. Glutathione reductase then reduces the oxidized glutathione to complete the cycle: GSSG + NADPH + H+ → 2 GSH + NADP+ Glutathione peroxidase is a tetramer, and the bovine erythrocyte enzyme has a molecular weight of 84,000. It is a selenium containing enzyme with 4 selenocysteine amino acid residues that participate in the actual mechanism of this enzyme..
Film developing - of chemicals : The first of these is developer, which makes the image visible. The second chemical is a stop bath, which stops the action of developer. (Sometimes plain water is used for this step.) It also helps to clean the developer residue off of the film to prevent contaminating the fixer. The third chemical is called fixer. It makes the image permanent and light-resistant. Fixer itself is slightly corrosive, so the film must be washed. Sometimes, it is then placed in a bath of a hypo clearing agent (and sometimes another material, such as selenium). It is then treated with a solution to prevent the appearance of hard-water stains, dried, and cut into strips of a convenient length. The film is now ready to be used in photographic printing..
Elements song - Tom Lehrer. The song is sung to the tune of Sir Arthur Sullivan's "Major General's Song" ("I am the very model of a modern major-general...") from The Pirates of Penzance. The song starts: There's antimony, arsenic, aluminum, selenium, And hydrogen and oxygen and nitrogen and rhenium ... and ends: ... These are the only ones of which the news has come to Harvard, And there may be many others but they haven't been discovered. Indeed, since that time, 11 more have been discovered, and 8 of those have been named..
Electron orbital - 15 Phosphorus 2 8 5 16 Sulfur 2 8 6 17 Chlorine 2 8 7 18 Argon 2 8 8 19 Potassium 2 8 8 1 20 Calcium 2 8 8 2 21 Scandium 2 8 9 2 22 Titanium 2 8 10 2 23 Vanadium 2 8 11 2 24 Chromium 2 8 13 1 25 Manganese 2 8 13 2 26 Iron 2 8 14 2 27 Cobalt 2 8 15 2 28 Nickel 2 8 16 2 29 Copper 2 8 18 1 30 Zinc 2 8 18 2 31 Gallium 2 8 18 3 32 Germanium 2 8 18 4 33 Arsenic 2 8 18 5 34 Selenium 2 8 18 6 35 Bromine 2 8 18 7 36 Krypton 2 8 18 8 37 Rubidium 2.
Discoveries of the chemical elements - it was later shown that Berzelius and Hisinger's cerium was actually a mixture of cerium, lanthanum and didymium. Cerium 1803 Martin Heinrich Klaproth; Jöns Jacob Berzelius and Hisinger Rhodium Palladium Osmium Iridium Magnesium At this point, Sir Humphry Davy pioneered the use of electricity from the Voltaic pile to decompose the salts of alkali metals, and so a number of thse metals were first prepared as the pure element: the beginning of the field of electrochemistry. Potassium 1807 Humphry Davy Calcium 1808 Humphry Davy Sodium 1807 Humphry Davy Barium 1808 Humphry Davy Iodine 1811 Bernard Courtois Lithium 1817 Arfvedson (metal prepared by Bunsen using electrolysis in 1855) [This is unclear] Cadmium 1817 Friedrich Strohmeyer Independently discovered by K.S.L Hermann Selenium 1817 Jöns Jacob Berzelius Silicon 1823 Jöns Jacob Berzelius Aluminium 1825.
Dietary mineral - the most important trace minerals include (in alphabetical order): chromium copper iodine iron magnesium manganese potassium selenium zinc Secondary trace minerals, not all of which have been definitively established as essential to human nutrition, include: bismuth cobalt molybdenum nickel rubidium strontium tellurium titanium tungsten vanadium Calcium and sodium are not generally considered trace minerals, as they are needed in larger quantities. Aluminium is an essential trace mineral, but is toxic in higher doses; due to the extensive use of aluminium in food packaging today, one is more likely to get too much than too little. Iron and potassium are needed in larger quantities than the other listed minerals and are sometimes included, sometimes not..
Deiodinase - the prohormone thyroxine to the active hormone triiodothyronine by the removal of an iodine atom. Deiodinases are unusual in that the enzyme contains selenium, in the form of an otherwise rare amino acid selenocysteine.
Dandruff - up to about once a fortnight. Dandruff is more common in the winter than the summer, probably because of the wearing of hats and central heating. Treatment There are some dandruff shampoos available, like Head & Shoulders.These shampoos contain selenium sulfide or zinc pyrithione, both of which slow down the rate of cell growth in the uppermost layer of skin on the head. Severe forms of dandruff, particlualy if accompanied by flaking or scaling on other parts of the body should be treated by a doctor, as there may be other causes or the patient may be suffering from seborrheic dermatitis( a condition that appears to be caused by a yeast infection) or psoriasis Causes There is speculation that dandruff is linked with Hair loss..
Alexander Graham Bell - telephone, Bell continued his experiments in communication, which culminated in the invention of the photophone-transmission of sound on a beam of light -- a precursor of today's optical fiber systems. He also worked in medical research and invented techniques for teaching speech to the deaf. The range of Bell's inventive genius is represented only in part by the 18 patents granted in his name alone and the 12 he shared with his collaborators. These included 14 for the telephone and telegraph, four for the photophone, one for the phonograph, five for aerial vehicles, four for hydroairplanes, and two for a selenium cell. In 1888 he founded the National Geographic Society. He was born at Edinburgh and comes of a family associated with the teaching of elocution. His grandfather in London, his.
Alan Beaven - and a trial attorney in New York. In 1992 he helped form the firm Stammell Tabacco and Singer in San Francisco. He successfully sued Shell Oil over its selenium discharges in 1992 on the behalf of California fishermen. In 1997 he sued the city of Pacifica, California for violating the United States Clean Water Act with its sewage treatment. Beaven died at 48, in the crash of United Airlines flight 93 in the September 11, 2001 Terrorist Attack. He was on his way to the San Francisco area to prepare for his final trial before a planned sabbatical to Bombay, India. It is believed that he was one of the passengers that overtook the hijackers after learning about the other three planes in the terrorist attack. He is survived by his.
Antioxidant - sources include citrus fruits (like oranges, sweet lime etc.), green peppers, broccoli, green leafy vegetables, strawberries, raw cabbage and tomatoes. vitamin E (tocopherol) is fat soluble and similarly protects lipids. Sources include wheat germ, nuts, seeds, whole grains, green leafy vegetables, vegetable oil and fish-liver oil. selenium It is best to get selenium through foods, as large doses of the supplement form can be toxic. Good food sources include fish, shellfish, red meat, grains, eggs, chicken and garlic. Vegetables can also be a good source if grown in selenium-rich soils. Several food additives (including ascorbic acid and tocopherol-derived compounds) are used as antioxidants to help guard against deterioration of food. (see: preservative).
Tellurium - are used except where noted. Tellurium is a chemical element in the periodic table that has the symbol Te and atomic number 52. A brittle silver-white metalloid which looks like tin, tellurium is chemically related to selenium and sulfur. This element is primarily used in alloys and as a semiconductor. Table of contents showTocToggle("show","hide") 1 Notable Characteristics 2 Applications 3 History 4 Occurrence 5 Compounds 6 Isotopes 7 Precautions 8 External Links Notable Characteristics Tellurium is a relatively rare element, in the same chemical family as oxygen, sulfur, selenium, and polonium (the chalcogens). When crystalline, tellurium is silvery-white and when it is in its pure state it has a metallic luster. This is a brittle and easily pulverized metalloid. Amorphous tellurium is found by precipitating it from a solution of tellurous.
Arsenic - Arsenic Germanium - Arsenic - Selenium P Ar Sb Full table General Name, Symbol, Number Arsenic, As, 33 Series Metalloids Group, Period, Block 15 (VA), 4 , p Density, Hardness 5727 kg/m3, 3.5 Appearance metallic grey Atomic Properties Atomic weight 74.92160 amu Atomic radius (calc.) 115 (114) pm Covalent radius 119 pm van der Waals radius 185 pm Electron configuration [Ar]33d10 4s2 4p3 e- 's per energy level 2, 8, 18, 5 Oxidation states (Oxide) +-3,5 (mildly acidic) Crystal structure Rhombohedral Physical Properties State of matter solid Melting point 1090 K (1503 °F) Boiling point 887 K (1137 °F) Molar volume 12.95 ×1010-3 m3/mol Heat of vaporization 34.76 kJ/mol Heat of fusion 369.9 kJ/mol Vapor pressure __ Pa at __ K Speed of sound __ m/s at.
