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Dimitri Mendeleev (1869) constructed a
table of rows and columns. He places
Elements horizontally according to
their atomic mass and vertically
according to their propertiesEnglish Scientist J.J Thomson (1897)
led to the discovery of electronsHenry Moseley (1913) Determined where
elements would go that were out of place from
Dimitri's table using atomic massNeils Bohr (1913) Proposed the Theory of the Hydrogen AtomJohann Dobereiner (1829) Discovered
similarities between element triads
that had chemically similar propertiesJohn Newlands (1864) Proposed
classifying the elements in order
of increasing atomic weights and were
grouped similarly to today's 7 groups
(e.g Alkali Metals, Metalloids, ect.)
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