Images Dated 5th December 2006

The Periodic Table Digital Illustration

In the late 19th century, Russian chemist Dmitri Mendeleev published his first attempt at grouping chemical elements according to their atomic weights. There were only about 60 elements known at the time, but Mendeleev realized that when the elements were organized by weight, certain types of elements occurred in regular intervals, or periods.
Today chemists officially recognize 118 elements and still use Mendeleev's periodic table of elements to organize them. The table starts with the simplest atom, hydrogen, and then organizes the rest of the elements by atomic number, which is the number of protons each contains. With a handful of exceptions, the order of the elements corresponds with the increasing mass of each atom

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Illustration, cross-section diagram of catalytic converter with arrows indicating the direction of emissions flow

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Sibling Rivalry

The only sister who would write to her brother, though the table had got folded down! The other sisters are sternly resolved to set off to Halnaby and the Castle, tho it is yet early early morning - Rembrondt. An early pen and ink sketch by Charles Lutwidge Dodgson, aka Lewis Carroll, circa 1850. (Photo by Hulton Archive/Getty Images)

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