Question

which group of elements was missing from mendeleev original periodic table​

Answer 1

Answer:

Gallium, germanium and scandium were all unknown in 1871, but Mendeleev left spaces for each and predicted their atomic masses and other chemical properties.

Answer 2

Noble gases

The group 18th of periodic table which is composed of Noble gases mainly was missing from the Mendeleev's periodic table. The reason for this is that Noble gases are least reactive, therefore, it was difficult to predict such elements which do not react with other elements. Hence, it was not part of that table.

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