-
400
The beginning of the periodic table BC
Democritus and Leucippus propose the idea of the atom, an indivisible particle that all matter is made of. -
Hennig Brand invented the Philosopher's stone
The Philosopher's stone is the ability to turn metals into pure Gold, he also discovered Phosphorus. -
Elements Discoverd
By the year 1809 about 47 elements had been discovered, scientists had begun to notice a patteren in the atom's structure. -
Organisation into the table
John Newlands organised all of the discovered 56 elements into eleven separate groups. Dimitri Mendellev used John's grouping and organised all of the elements into what is known as the periodic table. He used the atomic mass to decide where the elements go. -
Radiation Types
After Antoine Bacquerel discovered radioactivity, Ernest Rutherford named the three types of radiation, "Alpha, Beta and Gamma". -
Sir William Ramsey and Lord Reyleigh
This two scientists discovered a noble gas, they were then added to the periodic table as group O. -
Discovery of Electrons
J.J Thomson discovered Electrons, which were small negatively charged Particles. -
Henry Moseley
Henry Moseley labelled the elements with the atomic number based on the number of electrons in the atom rather than on the atomic mass. -
Glenn Seaborg
Glenn Seaborg identified Lanthanides and Actinides which are elements with atomic numbers higher than 92 and are placed in a separate section on the bottom of today's Periodic Table. -
Elements in 2006
There are 117 different elements on the periodic table, the most recent elements to be discovered are Meitnerium, Dramstadtium and Ununquadium.
