periodictable

1669 - Hennig Brand invented the Philosopher's Stone, which could turn metals into pure gold. He also discovered phosphorus

Sep 19, 1669

1680 - Robert Boyle also discovered phosphorus without knowing about Hennig Brand's discovery.

Sep 19, 1680

1863 - John Newlands organized the 56 then known elements into eleven separate groups based upon their atom structure.

Sep 19, 1863

1869 - Dimitri Mendellev used John Newlands' grouping and organized the elements into what is now known as the periodic table.

Sep 19, 1869

He used the atomic mass as the primary characteristic to decide where each element belonged in his table. The elements were arranged in rows and columns. He even left spaces for elements to be discovered because of the pattern he saw once he started organizing those elements known at that that time. His table looked like this

1886 - Antoine Becquerel discovered radioactivity.

Sep 19, 1886

1894 - Sir William Ramsay and Lord Rayleigh discovered the noble gases and they were added to the periodic table as group O.

Sep 19, 1894

1911 - Ernest Rutherford and Hans Geiger discovered that electrons moved around the nucleus of the cell's atom much like planets orbit the sun.

Sep 19, 1911

1911 - Ernest Rutherford and Hans Geiger discovered that electrons moved around the nucleus of the cell's atom much like planets orbit the sun.

Sep 19, 1914

1945 - 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 in today's Periodic Table.

Sep 19, 1945

As of October 16, 2006 there are 117 different elements. The most recent elements discovered are meitnerium, darmstadtium, and ununquadium.

Sep 19, 2006