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400
Discovery of atom
Atoms were first discovered by Democritus. -
Phosphorus discovered
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Hosphorus became public
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Johann Dobreiner
Johann Dobreiner grouped elements based on the elements -
Atomic Theory is first thought up
John Dalton comes up with the Atomic Theory -
47 elements discovered
47 elements were discovered. People began to see patterens in the elements. -
Law of traids
The law of traids is thought up which grouped elements based on similarities of the elements. -
X-Rays discovered
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". -
First Cathode Ray tube made.
J. Plucker invents the Cathode Ray tube, which is used for making X-rays -
Law of Octaves
The Law of Octaves is thought of, which again helps show similarities in elements discovered. -
Atomic Weight
Elements are organized by atomic weight. -
Dimitri Mendeleev
Development of the periodic table started by Dimitri Mendeleev. -
Radioactiviy
Radioactivity discovered by Antoine Bequerel -
Henry Moseley
Henry Moseley performed x-rays on known elements. -
X-rays
Henry Moseley performed x-rays on known elements. -
Noble gas
Group 0 was added to the periodic table, known as noble gases. -
Electrons
Electrons were discovered by J.J. Thomson. -
Electron Discovered
JJ thomson discovers the electron.He describes atoms as a ball of positive energy containing a number of electrons. -
Beta particles
Beta particles and electrons were discovered. -
Radioactivity
Radioactivity caused breakdown of atoms. -
Nucleus
Electrons orbit around the nucleus. Discovered by Rutherford and Hans Geiger. -
Orbitals
Electrons are in energy called orbitals. Radiation is released by movement -
Protons
Rutherford discovered protons in the nucleus. -
Isotopes discovered
Aston uses a spectrograph and discovers isotopes, variations in atoms where the amount of neutrons has been changed. -
Atoms are "succesive or bital shells of electrons"
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
Electron Cloud Theory introduced by Erwin Schrodinger. -
Nucleus of atom discovered to have a positive charge
Ernest Rutherford discovers that the nucleus of an atom has a positive charge. -
Neutrons and isotopes
Neutrons and isotopes were discovered by James Chadwick. -
Lanthanides and actinides
Lanthanides and actinides were discovered by Glenn Seaborg. -
Neutron Discovered
James Chadwick discovered the neutron. -
Alpha Particles made
John Douglas Cockcroft and Ernest Thomas Sinton Walton put lithium with protons and created alpha particles. -
Cyclotron invented.
Ernest Lawrence invented the cyclotron then realized potential for isotopes. -
First chain reaction from atoms releasing energy.
First chain reaction releasing energy from atoms by Enrico Fermi. -
First atomic bomb dropped.
The first atomic bomb is dropped by Us soldiers onto Japan for World War II -
60 elements
60 more elements were discovered.