Evolution of the periodic table

Question 1

Newland in 1800’s

Answer 1

tried to group things into octaves, and group them in a pattern which is a good idea but oxygen and iron are in the same group and they have very different properties. He ordered them by mass and tried to force things to be in the same group even if they didn’t have similar properties, didn’t really work.

Question 2

Mendeleev

Answer 2

ordered them by mass but left gaps this time as well. Also arranged in groups with similar patterns. Because he left gaps he could predict the properties of undiscovered elements – he was correct in his predictions, once the elements were found the fitted nicely into the table so it was accepted.

Question 3

Nowadays

Answer 3

Nowadays its very similar except we arrange them by proton number instead of mass number