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建立人际资源圈Basic_Chemistry
2013-11-13 来源: 类别: 更多范文
Basic Chemistry
In 1829 Johan Dobereimer first classified elements into a system of so-called triads. Previously, there were so few discovered atoms that this was impossible to group atoms in any way. Johans system was a pioneer in a series of scientific attempts to accurately place like elements, discovered and undiscovered into categories with similar properties. Although Johans system was far from accurate, it laid important foundations for John Newlands and Dimitri Mendeleev, other pioneers of our modern day periodic table. While parts of Newland and Mendeleevs ideas were also inaccurate, they did contribute important discoveries to our table. Newland discovered the relationship between atomic mass and chemical properties while Mendeleev arranged the elements by their atomic mass. Although Mendeleev is credited with the development of the periodic table, he made on critical error in his arrangement of the elements. In 1912 Henry Mosley discovered that if atoms were arranged by atomic numbers (as opposed to Mendeleevs arrangement by atomic mass) they would line up perfectly.
The modern periodic table contains a host of information concerning the elements within. Each element has a block stating its name, symbol, atomic mass, electron structure and atomic number. Elements in vertical rows are grouped into families
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