-
Atoms were first discovered by Democritus.
-
-
-
Johann Dobreiner grouped elements based on the elements
-
John Dalton comes up with the Atomic Theory
-
47 elements were discovered. People began to see patterens in the elements.
-
The law of traids is thought up which grouped elements based on similarities of the elements.
-
Willhelm Roentgen discovers chemicals that glowed in a CRT. Some rays within the chemicals weren't deflected by a magnetic field, and called these rays "X-Rays".
-
J. Plucker invents the Cathode Ray tube, which is used for making X-rays
-
The Law of Octaves is thought of, which again helps show similarities in elements discovered.
-
Elements are organized by atomic weight.
-
Development of the periodic table started by Dimitri Mendeleev.
-
Radioactivity discovered by Antoine Bequerel
-
Henry Moseley performed x-rays on known elements.
-
Henry Moseley performed x-rays on known elements.
-
Group 0 was added to the periodic table, known as noble gases.
-
Electrons were discovered by J.J. Thomson.
-
JJ thomson discovers the electron.He describes atoms as a ball of positive energy containing a number of electrons.
-
Beta particles and electrons were discovered.
-
Radioactivity caused breakdown of atoms.
-
Electrons orbit around the nucleus. Discovered by Rutherford and Hans Geiger.
-
Electrons are in energy called orbitals. Radiation is released by movement
-
Rutherford discovered protons in the nucleus.
-
Aston uses a spectrograph and discovers isotopes, variations in atoms where the amount of neutrons has been changed.
-
Neils Bohr becomes the father of Quantum Theory. He propses that atoms are "succesive or bital shells of electrons" and comes up with the "Bohr Planetary Model"
-
Electron Cloud Theory introduced by Erwin Schrodinger.
-
Ernest Rutherford discovers that the nucleus of an atom has a positive charge.
-
Neutrons and isotopes were discovered by James Chadwick.
-
Lanthanides and actinides were discovered by Glenn Seaborg.
-
James Chadwick discovered the neutron.
-
John Douglas Cockcroft and Ernest Thomas Sinton Walton put lithium with protons and created alpha particles.
-
Ernest Lawrence invented the cyclotron then realized potential for isotopes.
-
First chain reaction releasing energy from atoms by Enrico Fermi.
-
The first atomic bomb is dropped by Us soldiers onto Japan for World War II
-
60 more elements were discovered.