4.1.2 The Periodic Table

The Development of The Periodic Table.

Döbereiner (1829)

Grouped elements in triads (such as Lithium, Sodium and Potassium) based on similar chemical an physical properties. He also proved that the properties of the middle elements could be predicted based on the other 2.

Newlands (1856)

Grouped elements in octaves as he noticed similarities in elements which had a difference in atomic mass of 7.The noble gases had not been discovered yet and he didn't leave space in his table for new elements even having to cram 2 in one box.

Mendeleev (1869)

Grouped elements in vertical columns (groups) according to their properties and in ascending atomic number. He left gaps in his table for undiscovered elements and was able to accurately predict the properties of those elements.

Group 0 - Noble Gases

Noble Gases ate