1-16-08

Metallic Bonding

      Metallic bonding is the electrostatic attraction between delocalised electrons, called conduction electrons, and the metallic ions within metals. Because it involves the sharing of free electrons among a lattice of positively-charged metal ions, metallic bonding may be compared to that within molten salts.

      Metallic bonds are non-polar, because in alloys there is little difference among the electronegative of the atoms participating in the bonding interaction and, the electrons involved in the interaction are delocalised throughout the crystalline structure of the metal.

      The metallic bond also accounts for many characteristics of metals. These include strength, malleability, ductility, conduction of heat and electricity, and luster. Without metallic bonding, metals would not be as useful as they are now.

Observing Nanscale Metallic Puddles And Mystery Behavior In Electrons

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Sciencedaily, (2007), Observing Nanscale Metallic Puddles And Mystery Behavior In Electrons

      In collaboration with the Center for Integrated Nanotechnologies at Los Alamos, an international team of researchers has, for the first time, viewed on a nanoscale the formation of mysterious metallic puddles that facilitate the transition of an electrically insulating material into an electrically conducting one. The research may lead to a better understanding of superconductors–materials that conduct electricity without energy loss–or development of better materials for powering high-speed electronics.

      For decades scientists have puzzled over how this transformation to a fully metallic state–known as “Mott” metal-insulator transition–occurs. Balatsky, a Los Alamos condensed-matter theorist, believed, like many other scientists, that the transition begins when metallic puddles begin forming at sites of impurities or imperfections within the lattice. The puddles grow until they touch, and at that point the material becomes conductive, or superconductive.

“We had evidence to believe that metallic puddles were forming in an inhomogenous manner within the material at the transition phase, but we had no way of proving it,” said Balatsky. “If you had the right glasses that could see something extremely small, you could see this process occurring.”

      By reading this articl, I learned that people viewed on a nanoscale, the formation of mysterious metallic puddles that facilitate the transition of an electrically insulating material into an electrically conducting one

Catalyst-free Chemistry Makes Self-healing Materials More Practical

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ScienceDaily, (2007), Catalyst-free Chemistry Makes Self-healing Materials More Practical

      A new catalyst-free, self-healing material system developed by researchers at the University of Illinois offers a far less expensive and far more practical way to repair composite materials used in structural applications ranging from airplane fuselages to wind-farm propeller blades.

      The new self-healing system incorporates chlorobenzene microcapsules, as small as 150 microns in diameter, as an active solvent. The expensive, ruthenium-based Grubbs’ catalyst, which was required in the researchers’ first approach, is no longer needed. During normal use, epoxy-based materials experience stresses that can cause cracking, which can lead to mechanical failure. Autonomous self-healing — a process in which the damage itself triggers the repair mechanism — can retain structural integrity and extend the lifetime of the material.

      By reading this article, I learned that a new self-healing material has been developed. It offers a new way to repair composite materials used in structural applications.

Scientists Unravel Plants’ Natural Defenses

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Sciencedaily, (2007), “Scientists Unravel Plants’ Natural Defenses”

      A team of researchers, led by the University of Sheffield and Queen Mary, University of London, has discovered how plants protect their leaves from damage by sunlight when they are faced with extreme climates. The new findings, which have been published in Nature, could have implications both for adapting plants to the threat of global warming and for helping man better harness solar energy.

      Photosynthesis in plants relies upon the efficient collection of sunlight. This process can work even at low levels of sunlight, when plants are in the shade or under cloud cover for example. However, when the sun is very bright or when it is cold or very dry, the level of light energy absorbed by leaves can be greatly in excess of that which can be used in photosynthesis and can destroy the plant. However, plants employ a remarkable process called photoprotection, in which a change takes place in the leaves so that the excess light energy is converted into heat, which is harmlessly dispersed. Until now, researchers hadn’t known exactly how photoprotection works. By joining forces with their physicist colleagues in France and the Netherlands, the UK team have determined how this process works. They were able to show how a small number of certain key molecules, hidden among the millions of others in the plant leaf, change their shape when the amount of light absorbed is excessive; and they have been able to track the conversion of light energy to heat that occurs in less than a billionth of a second.

      By reading this article, I learned that plants can protect themselves from sunlight. I learned that during photoprotection, ceartain molecules change their shape to protect themselves from to much sunlight.

11-15-07

The Manhattan Project           

       The Manhattan Project was a very important event in U.S. history. Without it, World War 2 would have lasted much longer then it did. I believe the creation of the atomic bomb helped the United States in many ways. Without it, the world would be much different then it is today.           

      If the atomic bomb had not been created and was not used against Japan in World War 2, the war would have probably lasted much longer then it did. It may even have still been going on today. Now that America can create an atomic bomb, other countries do not want to go to war with us. They want to remain at peace. The creation of the atomic bomb also gave America more power. Had the atomic bomb not been created, other countries may not have had as much respect for America as they do now.           

      I believe The Manhattan Project was very helpful to America. It made our country stronger and made all other countries show respect. It also ended World War 2 earlier, which without it may have still been going on today.

Chemists Discover Molecule Considered Too Unstable To Exist

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EVANSTON, Ill., (2002), Chemists Discover Molecule Considered Too Unstable To Exist

      Organic chemistry textbooks will need to be revised to recognize a chemical species that chemists have discovered at Northwestern University. The species — pentamethylcyclopentadienyl cation — was thought not to exist for long because theory said it was unstable. I’ve said this molecule is unstable and doesn’t exist dozens of times in organic chemistry class, but, as it turns out, the molecule had different ideas,” said Joseph B. Lambert, Clare Hamilton Hall Professor of Chemistry at Northwestern. He and graduate student Lijun Lin discovered that the cation (a positively charged ion) is stable in the solid state for weeks at room temperature and in solution.           

     The cyclopentadienyl cation is a common textbook example of an antiaromatic molecule, a molecule so electronically unstable and, therefore, extremely reactive that it should not exist for any length of time. Lambert believes the cation now should be described as non aromatic. They found that the cation was stable in the open atmosphere at room temperature. The cation achieves this stability by avoiding interactions among electrons. This condition is known as localized bonding. Normally molecules are stabilized by delocalization of electrons, whereby they may be located in more than one part of the molecule.           

      By reading this article, I learned that a new molecule was discovered. People thought it was too unstable to exist but found that at certain temperatures, the molecule is stable. 

11-08-07

Chemists Forge a New Form of Iron

 www.sciencedaily.com  

University of Wisconsin, (2006), “Chemists Forge a New Form of Iron”     

     An international team of chemists has discovered a new and unexpected form of iron, a finding that adds to the fundamental understanding of an element that is among the most abundant on Earth, and that in nature is fundamental for life.    

      The new species of iron found by John Berry and his colleagues is designated iron VL, which means the atom, has just two valance electrons and is highly reactive as it seeks to regain iron’s eight electron stable configurations by grabbing electrons from other elements. The new form is so reactive it can only be studied at very low temperatures.     

     By reading this article, I learned that a new form of iron has been discovered. I also learned that it is so reactive that it can only be studied at about minus 40 degrees F.

     The Manhattan Project was the project to develop the first atomic bomb during World War II by the United States, the United Kingdom, and Canada. The project succeeded in developing and detonating three nuclear weapons in 1945. Born out of a small research program in 1939, the Manhattan Project eventually employed more than 130,000 people and cost nearly $7 million. It resulted in the creation of multiple production and research sites that operated in secret. The three primary research and production sites of the project were the plutonium-production facility at what is now the Hanford Site, the uranium-enrichment facilities at Oak Ridge, Tennessee, and the weapons research and design laboratory, now known as Los Alamos National Laboratory.           

     Ernest Rutherford, Robert Oppenheimer, and Robert Serber were some of the main people involved in the Manhattan Project. They worked on uranium research and nuclear fission to create an atomic bomb. The conferences in the summer of 1942 provided the detailed theoretical basis for the design of the atomic bomb, and convinced Oppenheimer of the benefits of having a single centralized laboratory to manage the research for the bomb project, rather than having specialists spread out at different sites across the United States. The bombs that were created were used against Japan in 1945. As a result, World War II ended.