Manganese Facts - Periodic Table of the Elements

Manganese Facts - Periodic Table of the Elements Manganese  Basic Facts Atomic Number: 25 Symbol: Mn Atomic Weight: 54.93805 Discovery: Johann Gahn, Scheele, Bergman 1774 (Sweden) Electron Configuration: [Ar]4s2 3d5 Word Origin: Latin magnes: magnet, referring to the magnetic properties of pyrolusite; Italian manganese: corrupt form of magnesia Properties: Manganese has a melting point of 1244/-3 °C, boiling point of 1962 °C, specific gravity of 7.21 to 7.44 (depending on allotropic form), and valence of 1, 2, 3, 4, 6, or 7. Ordinary manganese is a hard and brittle gray-white metal. It is chemically reactive and slowly decomposes in cold water. Manganese metal is ferromagnetic (only) after special treatment. There are four allotropic forms of manganese. The alpha form is stable at normal temperatures. The gamma form changes to the alpha form at ordinary temperature. In contrast to the alpha form, the gamma form is soft, flexible, and easily cut. Uses: Manganese is an important alloying agent. It is added to improve the strength, toughness, stiffness, hardness, wear resistance, and hardenability of steels. Together with aluminum and antimony, especially in the presence of copper, it forms highly ferromagnetic alloys. Manganese dioxide is used as a depolarizer in dry cells and as a decolorizing agent for glass that has been colored green due to iron impurities. The dioxide is also used in drying black paints and in the preparation of oxygen and chlorine. Manganese colors glass an amethyst color and is the coloring agent in natural amethyst. The permanganate is used as an oxidizing agent and is useful for qualitative analysis and in medicine. Manganese is an important trace element in nutrition, although exposure to the element is toxic in higher quantities. Sources: In 1774, Gahn isolated manganese by reducing its dioxide with carbon. The metal may also be obtained by electrolysis or by reducing the oxide with sodium, magnesium, or aluminum. Manganese-containing minerals are widely distributed. Pyrolusite (MnO2) and rhodochrosite (MnCO3) are among the most common of these minerals. Element Classification: Transition Metal Isotopes: There are known 25 isotopes of manganese ranging from Mn-44 to Mn-67 and Mn-69. The only stable isotope is Mn-55. The next most stable isotope is Mn-53 with a half-life of 3.74 x 106 years. Density (g/cc): 7.21 Manganese Physical Data Melting Point (K): 1517 Boiling Point (K): 2235 Appearance: Hard, brittle, grayish-white metal Atomic Radius (pm): 135 Atomic Volume (cc/mol): 7.39 Covalent Radius (pm): 117 Ionic Radius: 46 (7e) 80 (2e) Specific Heat (20 °C J/g mol): 0.477 Fusion Heat (kJ/mol): (13.4) Evaporation Heat (kJ/mol): 221 Debye Temperature (K): 400.00 Pauling Negativity Number: 1.55 First Ionizing Energy (kJ/mol): 716.8 Oxidation States: 7, 6, 4, 3, 2, 0, -1 The most common oxidation states are 0, 2, 6 and 7 Lattice Structure: Cubic Lattice Constant (Ã…): 8.890 CAS registry number: 7439-96-5 Manganese Trivia: Manganese dioxide is used to make clear glass. Normal silica glass is tinted green and the manganese oxides add a purple tint to the glass that cancels out the green. Because of this property, glassmakers called it glassmakers soap.Manganese is found in the enzymes necessary to metabolize fats and carbohydrates.Manganese is found in the bones, liver, kidneys, and pancreas.Manganese is important in the processes that form bones, clots blood, and regulates blood sugar.As important as manganese is to our health, the body does not store manganese.Manganese is the 12th most abundant element in the Earths crust.Manganese has an abundance of 2 x 10-4 mg/L in sea water (parts per million).The permanganate ion (MnO4-) contains the 7 oxidation state of manganese.Manganese was found in a black mineral called magnes from the ancient Greek kingdom of Magnesia. Magnes was actually two different minerals, magnetite and pyrolusite. The pyrolusite mineral (manganese dioxide) was called magnesia. Manganese is used in steel production to fix the sulfur found in iron ores. It also strengthens steel and prevents oxidation. References: Los Alamos National Laboratory (2001), Crescent Chemical Company (2001), Langes Handbook of Chemistry (1952), CRC Handbook of Chemistry Physics (18th Ed.) International Atomic Energy Agency ENSDF database (Oct 2010)

Rivalry Between Beijing vs. Shanghai

Rivalry Between Beijing vs. Shanghai Beijing and Shanghai are arguably China’s two most famous and most important cities. One is the center of government, the other the center of modern commerce. One is steeped in history, the other is a glittering tribute to modernity. You might imagine that the two fit together like yin and yang, complimenting each other, and maybe that’s true... but they also hate each other. Beijing and Shanghai have a fierce rivalry that’s been going on for decades, and it’s fascinating. What Shanghai Thinks of Beijing and Vice Versa In Shanghai, people will tell you Beijing ren (Ã¥Å'â€"ä º ¬Ã¤ º º, â€Å"Beijingers†) are arrogant and uncouth. Although the city is host to more than 20 million people, Shanghai’s denizens will tell you they act like peasants- friendly, perhaps, but blustery and uncultured. Certainly not as refined and fashionable as Shanghaiers! â€Å"They [Beijingers] smell like garlic,† one Shanghai resident told the LA Times in an article on the rivalry. In Beijing, on the other hand, they’ll tell you that Shanghai people only care about money; they’re unfriendly to outsiders and selfish even among themselves. Shanghai men are said to place too much importance on business while being impotent pushovers at home. Shanghai women are supposedly bossy dragon ladies who push their men around whenever they’re not too busy spending their money shopping. â€Å"All they care for is themselves and their money,† a Beijinger told the LA Times. When Did the Rivalry Originate? Although China has dozens of huge cities these days, Beijing and Shanghai have played a major role in China’s culture for centuries. At the beginning of the twentieth century, Shanghai clearly had the upper hand it was the center of Chinese fashion, the â€Å"Paris of the East†, and Westerners flocked to the cosmopolitan city. After the revolution in 1949, though, Beijing became the center of China’s political and cultural power, and Shanghai’s influence waned. When China’s economy was opened up following the Cultural Revolution, Shanghai’s influence began to rise again, and the city became the heart of Chinese finance (and fashion). Of course, it’s not all macroeconomics and geopolitics. Although denizens of both cities would like to believe their cities are more influential, there is also a grain of truth to the stereotypes and jokes that get passed around; Shanghai and Beijing do have very different cultures, and the cities look and feel different. The Rivalry Today These days, Beijing and Shanghai are considered mainland China’s two greatest cities, and although the government being located in Beijing means that Beijing will probably have the upper hand for the foreseeable future, but that hasn’t stopped the two from competing. The Beijing Olympics in 2008, followed by Shanghai’s World Expo in 2010, have been a great source of fodder for comparative arguments about the virtues and faults of the two cities, and denizens of both will argue it was their city that put on the better show when they were on the world stage. Of course, the rivalry also plays out in professional sports. In basketball, a match between the Beijing Ducks and the Shanghai Sharks can be counted on to be contentious, and both teams are among the best in the league historically, though it has been more than a decade since the Sharks made an appearance in the finals. In soccer, Beijing Guoan and Shanghai Shenhua duke it out for bragging rights each year (though again, Beijing has had more recent success than Shanghai in the league). It’s unlikely that Beijingers and Shanghaiers will ever see totally eye to eye. It’s worth noting that the Beijing versus Shanghai feud sometimes even extends the ​city’s expatriate communities, so if you’re looking for a Chinese city to live in, choose wisely.