-
- Hennig Brand invented the Philosopher's Stone, which could turn metals into pure gold. He also discovered phosphorus.
-
47 elements had been discovered and named. Scientists began to see patterns in their atom structures.
-
- John Newlands organized the 56 then known elements into eleven separate groups based upon their atom structure.
-
Antoine Becquerel discovered radioactivity.
-
Sir William Ramsay and Lord Rayleigh discovered the noble gases and they were added to the periodic table as group O.
-
- J. J. Thomson discovered electrons which were small negatively charged particles.
-
J. D. Cockroft and Ernest T. S. Walton worked together in splitting the atom when working with lithium which they bombarded with protons. The lithium nucleus was divided into two helium nuclei.
-
- Ernest O. Lawrence, Milton Stanley Livingston and Milton White worked on the first cyclotron at the University of California in Berkeley. A cyclotron is in the picture below.
-
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. As of October 16, 2006 there are 117 different elements. The mos
