In chemistry, the ball-and-stick model is a molecular model of a chemical substance, to display both the three-dimensional position of the atoms and the bonds between them. The atoms are represented by spheres, connected by rods which represent the bonds. Double and triple bonds are represented by two or three curved rods or alternately by positioned sticks for the sigma and pi bonds. In a good model, the angles between the rods should be the same as the angles between the bonds, the distances between the centers of the spheres should be proportional to the distances between the corresponding atomic nuclei; the chemical element of each atom is indicated by the sphere's color. In a ball-and-stick model, the radius of the spheres is much smaller than the rod lengths, in order to provide a clearer view of the atoms and bonds throughout the model; as a consequence, the model does not provide a clear insight about the space occupied by the model. In this aspect, ball-and-stick models are distinct from space-filling models, where the sphere radii are proportional to the Van der Waals atomic radii in the same scale as the atom distances, therefore show the occupied space but not the bonds.
Ball-and-stick models can be virtual computer models. The former are built from molecular modeling kits, consisting of a number of coil springs or plastic or wood sticks, a number of plastic balls with pre-drilled holes; the sphere colors follow the CPK coloring. Some university courses on chemistry require students to buy such models as learning material. In 1865, German chemist August Wilhelm von Hofmann was the first to make ball-and-stick molecular models, he used such models in lecture at the Royal Institution of Great Britain. Specialist companies manufacture models to order. One of the earlier companies was Woosters at Bottisham, Cambridgeshire, UK. Besides tetrahedral and octahedral holes, there were all-purpose balls with 24 holes; these models allowed rotation about the single rod bonds, which could be both an advantage and a disadvantage. The approximate scale was not consistent over all elements; the Beevers Miniature Models company in Edinburgh produced small models beginning in 1961 using PMMA balls and stainless steel rods.
In these models, the use of individually drilled balls with precise bond angles and bond lengths enabled large crystal structures to be created in a light and rigid form. VSEPR theory
Leandro Lourenço Franco known as Lê, is a Brazilian football Forward. After playing with South American giants Colo-Colo, he got offers to play in well known Mexican teams, such as Cruz Azul. Went on to play in Super League Greece team Atromitos, his team relegated to Beta Ethniki, so he looked for new options. He got an offer to play for Águila, one of the biggest clubs in El Salvador and Central America. In 2009, he signed a one-year contract with fellow Salvadorans Luis Ángel Firpo. In 2010 he moved back to his native Brazil to play with Marília Atlético Clube only to join Sport Boys in Peru in 2011. Sambafoot paginas.terra
Ashikaga is a city located in Tochigi Prefecture, Japan. As of May 2015, the city had an estimated population of 149,711, a population density of 842 persons per km², its total area is 177.76 km². Ashikaga is located in the far southwestern corner of Tochigi Prefecture, bordering on Gunma Prefecture to the north and south; the Watarase River flows through the center of the city. It is located 80 km north of Tokyo. Tochigi Prefecture Sano Gunma Prefecture Tatebayashi Kiryū Ōta Ōra During the Heian Period, Ashikaga was developed by Minamoto no Yoshikuni, whose descendants became the Ashikaga clan; the area was noted from this period for its academy, the Ashikaga Gakkō. During the Edo period, it was the center of Ashikaga Domain. Following the Meiji restoration, the town of Ashikaga within Ashikaga District, Tochigi was established with the creation of the municipalities system on April 1, 1889, it was elevated to city status on January 1, 1921. Ashikaga annexed the neighboring village of Keno on March 3, 1951 and the town of Yamabe on April 1, 1953.
This was followed on August 1, 1954 by the villages of Mie and Yamamae, on November 1, 1954 by the villages of Kitago and Nagusa. On April 1, 1959, Ashikaga annexed the village of Tomita, the northern half of the village of Yabagawa on July 1, 1960. On October 1, 1962, Ashikaga annexed the towns of Sakanishi. Ashikaga District was dissolved by this final merger. Ashikaga has long been noted for its textile industry, but in recent years, it has become known as an industrial and commercial city producing various aluminum, machine metal works and products. In the agricultural sector, Ashikaga is noted for its tomatoes. Ashikaga Institute of Technology Ashikaga Junior College Ashikaga has 22 primary schools, 12 middle schools and eight high schools. JR East – Ryōmō Line Tomita - Ashikaga - Yamamae - Omata Tobu Railway – Tobu Isesaki Line Agata - Fukui - Tōbu-Izumi - Ashikagashi - Yashū-Yamabe Kita-Kantō Expressway – Ashikaga IC Japan National Route 50 Japan National Route 293 Japan National Route 407 Ashikaga Gakkō: referred to as the oldest school in Japan.
Ashikaga Flower Park: Japan's oldest and largest wisteria. Orihime Shrine: This shrine was built in 1879, the guardians of the textile city, Ashikaga. Bannaji Temple: A temple known for its association with the Ashikaga clan. Kurita Museum: This museum has a fine collection of Imari and Nabeshima porcelains. Watarase River Fireworks display, which takes places on the first Saturday of August attracts thousands of people from around the Kantō area. Coco Farm & Winery, located in the foothills on the outskirts of town. Founded around 1950, the vineyards are tended by adults with special needs and staff members living in community. During the third weekend of November, a harvest festival is held with live wine tasting. Thousands of visitors attend every year. Springfield, United States Jining, China Kamakura, Japan Mitsuo Aida and calligrapher George Akiyama, manga artist Masao Urino, director Yumiko Hara, marathon runner Noriyo Tateno, professional wrestler Atsushi Abe, voice actor Asteroid 9887 Ashikaga, named after the city Media related to Ashikaga, Tochigi at Wikimedia Commons Official Website Ashikaga travel guide from Wikivoyage