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Chemistry 3: History of the Periodic Table
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- 1THE EARLY PERIODIC TABLEIn the early 18oo's, there were two obvious ways to categorise elements:
1) their physical and chemical properties
2) their relative atomic mass
Nobody knew of atomic structure or protons and neutrons - 2THE EARLY PERIODIC TABLE: JOHN NEWLANDS'Newlands' started to arrange elements in a table in 1864, by order of relative atomic mass. He noticed that every 8th element had similar properties (Newlands' Octaves). However this pattern broke down on the 3rd row.
- 3THE EARLY PERIODIC TABLE: DMITRI MENDELEEVMendeleev arranged the known elements of the time (50) in a table, by order of relative atomic mass. However, he left gaps in order to keep elements with similar properties in the same groups. The gaps predicted the properties of unknown elements.
- 4THE EARLY PERIODIC TABLE: COMPARISONS-Mendeleev and Newlands both arranged elemts by RAM.
-Newlands only included known elements, Mendeleev left gaps for undiscovered elements.
-Newlands was criticised for grouping some elements that didn't belong together e.g. O and Fe
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- Fichas sobre Chemistry 3: History of the Periodic Table, creado por hk13 el 10/01/2016.
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