-
400 BCE
Democritus
He suggested atoms. -
John Dalton - http://modernbiochemistry.weebly.com/uploads/5/3/3/8/53388477/1966726_orig.jpg
Proposed the modern atomic theory. Dalton's atomic theory proposed that all matter was composed of atoms, indivisible and indestructible building blocks. While all atoms of an element were identical, different elements had atoms of differing size and mass. Dalton’s atomic theory also stated that all compounds were composed of combinations of these atoms in defined ratios. -
Dmitri Mendeleev - https://swh-826d.kxcdn.com/wp-content/uploads/2010/08/periodic_table.gif
He created the first periodic law and created the first periodic table. The Periodic Law states that when elements are arranged according to their atomic number. -
Eugene Goldstein - https://d1ox703z8b11rg.cloudfront.net/uploads_image/7e2dd6dc-5c33-42f5-a45d-15642df6b214/5070ca85bc59058412258b20dd83689a.jpeg
He discovered protons and canal rays with the experiments he did with cathode rays. -
J.J. Thomson - http://wps.prenhall.com/wps/media/objects/165/169289/GIFS/AAAUATG0.JPG
He discovered the electron by experimenting with a Crookes. He demonstrated that cathode rays were negatively charged. He created the plum pudding model. -
Max Planck - https://sites.google.com/site/csetstudyguidechemistry/_/rsrc/1472780978732/home/atomic-structure-1-2/max_planck_atom.gif
His work in thermodynamics led to the creation of his quantum theory. -
Robert Millikan - http://chemed.chem.purdue.edu/genchem/history/gifs/fig6_4.gif
He did the oil drop experiment that helped to understand the charge of an electron. This contributed to our understanding of the structure of the atom and atomic theory. -
Ernest Rutherford - http://images.tutorcircle.com/cms/images/44/atom(1).png
He did the gold foil experiment which demonstrated that the atom has a tiny and heavy nucleus. -
Niels Bohr - https://study.com/cimages/multimages/16/bohr_model_of_an_atom_simple.png
He proposed that the hydrogen atom was based on the quantum theory and energy is transferred in defined quantities. Electrons move around the nucleus but only in designated orbits. -
Werner Heisenberg - http://science-class.net/archive/science-class/Notes/Images_8th_Notes/atom.jpg
He was known for his principle and theory of quantum mechanics. He also found different forms of the hydrogen atom. -
Erwin Schrodinger -
He furthered the Bohr atom model. He also used mathematical equations to describe the likelihood of finding an electron in certain positions. -
James Chadwick - https://sites.google.com/site/historyofanatom/_/rsrc/1468750669870/james-chadwick/Chadwick%20neutron.png
Ηe discovered the Neutron in atoms. He found that neutrons have the same contribution to the atomic weight as protons.
