-
The law of the triads
The middle element in the triad had atomic weight that was the average of the other two members. -
Period: to
Development of the periodic table
-
Discovered elements
There were about 60 elements which had already been discovered by 1860 -
the first periodic table
alexandre Beguyer de Chancourtois published a list of all the known elements. The list was constructed as a helical graph wrapped around a cylinder. Elements with similar properties occupied positions on the same vertical line of cylinder. -
Law of the octaves
Elements exhibit similar behavior to the eighth element following it in the table. -
Discovered the periodic table
Dmitri Mendeleev decided to stay at home to work on a way to arrange all the chemical elements so instead of going to visit a factory he proceeded to dicover the periodic table. first he ordered it in rows horisontally but found it easier to understand when ordered in columns. -
discovery of the noble gases
after the discovery of argon in 1895, William Ramsey decided that a new group should be established in the periodic table because argon did not fit into any of the other categories. -
Moseley's table
moseley arranged the elements in increasing atomic numbers instead of atomic mases
