Periodic Table History. Dobereiner. He put elements with similar chemical properties together They went into in groups of 3 He noticed these trends in groups of elements such as:. Atomic Weight of “middle” element is average of other two – approx. Can you name these elements ?.
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Periodic Table History
Atomic Weight of “middle” element is average of other two – approx.
Can you name these elements ?
(i.e. had 7 groups)
Gaps left for undiscovered elements
Group 0 elements missing
Elements discovered since 1869 missing
D-block elements arranged as subgroups beside each main group
Elements arranged in order of increasing atomic weight in almost all cases.
Gaps have been filled
Group 0 elements included
Elements discovered since 1869 included
D-block elements arranged as subgroups in a separate block
Elements arranged in order of increasing atomic number