Development of periodic table

Question 1

John Newlands

Answer 1

-Law of Octaves
-Put all elements known in table based off relative atomic mass
-By ordering it this way, there were many elements placed with each other that didn’t have the same properties.

Question 2

Early work of Dimitri Mendeleev

Answer 2

-Also ordered elements in order of relative atomic mass.
-Realised chemical and physical properties related to atomic mass in periodic way.
-Arranged them so that elements with similar properties fell into vertical columns.

Question 3

Mendeleev’s explanation

Answer 3

-There some gaps that he believed were elements yet to be discovered
-Able to work out atomic mass of missing elements and predict their properties.
-When missing elements discovered, their properties were close to his predictions.