On the shoulders of giants


particles of matter, called atoms... atoms of the same element are identical in all respects, particularly weight." - Dalton



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"The chemical elements are composed of... indivisible particles of matter, called atoms... atoms of the same element are identical in all respects, particularly weight." - Dalton

Doberiner Dobereiner noted that similar elements often had relative atomic masses, grouping elements in ‘triads’.

Dechancourtois De Chancourtois'vis Tellurique paper, describing his3D periodic table, was published by the French Academy of Sciences in 1862, but without the visual he had submitted, was poorly understood, and was little noticed for 11 years, but re-introduced the telluric screw after Mendeleev's periodic table attracted attention among chemists.

Cannizaro Stanislao Cannizaro determined atomic weights for the elements known in the 1860s, then a table was arranged by Newlands, with the elements given a numbers in series in order of their atomic weights, beginning with Hydrogen. This made evident that "The eighth element, starting from a given one, is a kind of repetition of the first", which Newlands called the Law of Octaves.

NewlandsThe periodic law, however, appears to have been independently formulated by at least six people within one decade - De Chancourtois, Newlands, Lothar Meyer, Mendeleev, Hinrichs, and Odling. Periodic tables have always been related to the way scientists thought about the shape and structure of the atom, and the relationships between elements, so has changed accordingly over time.

Meyer same

Mendeleyev same

Moseley


SeaborgInto the 1930s the heaviest elements were being put up in the body of the periodic table, and Glenn Seaborg "plucked those out" while working with Fermi in Chicago, naming them the Actinide series, which later permitted proper placement of subsequently 'created' elements - the Transactinides, changing the periodic table yet again. These elements were shown separate from the main body of the table.

GETTING THE LAY OF THE LAND: PERIODICALLY ORGANIZED

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1. Why are the elements placed in specific places on the Periodic Table? The




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