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law of trials prposed
In 1829 Dobereiner proposed the Law of Triads: Middle element in the triad had atomic weight that was the average of the other two members. -
first 60 elements
in 1860 the first 60 elements found -
the first periodic table had been published
the first periodic table was made by proffesor Alexandre Beguyer de Chancourtois -
new arrangment of periodic table perposed
Dimitri Mendeleev proposed arranging elements by atomic weights -
17 group table with eight columns
In 1871 Mendeleev revised the 17-group table with eight columns (the eighth group consisted of transition elements). -
discoverd the inert gases
In 1895 Rayleigh reported the discovery of a new gaseous element named argon. -
elements xrayed
Soon after Rutherford's landmark experiment of discovering the proton in 1911, Henry Moseley subjected known elements to x-rays. -
last major change to the periodic table
Starting with plutonium in 1940, Seaborg discovered transuranium elements 94 to 102 and reconfigured the periodic table by placing the lanthanide/actinide series at the bottom of the table. -
seaborg got a nobel prize
In 1951 Seaborg was awarded the Nobel Prize in chemistry and element 106 was later named seaborgium (Sg) in his honor.