Mendeleev's table

Question 1

How was Mendeleev’s table created?

Answer 1

1) Mendeleev put the elements in order of the relative atomic masses.
2) He checked the properties of the elements and their compounds.
3) He swapped the places of some elements so that elements with similar properties lined up.
4) He left gaps where he thought there were other elements and predicted their properties.
5) When these elements were discovered, Mendeleev’s predictions fitted the properties very well.