-
400 BCE
Democritus
atoms were uniform ,solid, hard, incompressible, and there hard. -
330 BCE
Solar system model
Describes atoms as consisting of a nucleus with a number of electrons in orbits around that nucleus -
350
Plato
Solid forms of matter are composed of individual elements shaped like triangles -
501
The Alchemists
That all metals were formed from two principles (Mercury and Sulfar) -
Robert Boyle
He believed that everything was composed of very tiny proporties -
Antone Lavoisier
Grounded in the law of conversation of mass exploring matter was converted during chemical changes -
John Dalton
Discovered the atomic theroy all matter was compressed of indivisible and indestructible atoms -
Billiard ball model
He defined an atom to be a ball-like structure as the concepts of the atomic nucleus and electrons were unknown at the time -
Amedeo Avogadro
Equals volumes opf gases of the same temperature and pressure contain the same number of molecules -
Dmitri Mendeleev
Elements arranged according to the value of their atomic weights. -
JJ Thompson
Composed the plum pudding model of the atom. (soap) -
Pierre and Marie Curie
Discovered the strongly radioactive elements and radium which occur naturally in minerals. -
Plum pudding model
Depects the electrons as a negatively charged particles embedded in a sea of positive charge -
Albert Einstein
proved the existence of atoms. Any liquid is made up of particles -
Robert Millikan
That electron did have a discrete, even charge -
Ernest Rutherford
Described atom as having tiny, decease charged core called the nucleus -
Neils Bohr
Theory for the hydrogen atom. Some physical quantities only take discrete values -
Henery G.J Mosley
Frequency of the x-ray by an atom is proportional to its atomic number -
Electron Cloud model
Shows a practicular area in which an electron is likely to be -
Erwin Schrodinger
the behavior of electrons within atoms could be explained by treating them mathematically as matter waves. -
James Chadwich
Discovery of the neutron