-
340
Aristotle B.C.
He believed that stuff can be broken into elements and elements are atoms with different masses.He discovered this through observation. He believed that the atom had fire, earth, air, and water elements combined. -
450
Democritus B.C.
He believed that matter is composed of tiny particles and are solid and invisible, homogeneous, and they differ in size and shape he called them atoms. He used a microscope to determine this idea.He believed the atom had no protons, neutrons, and electrons. -
Dalton
www.universetoday.comHe believed that elements exsit in descrete packets of matter.He also discovered that certain gasses can only be combined in certain proportions. -
Thomson
www.scienceblogs.comHe took the idea of the atom and tried to incorporate the evidencefor the electron.He used 'Cathode Rays" (beams of electrons,by having the beam interact with electric and magnetic fields).He called it the "Plumb Pudding Model". -
Rutherford
www.iun.edu.comHe discovered the nucleus most of the atom is empty space.He used a thin sheet of gold foil called the "Planetry Model". -
Bohr
He believed that an elecctron can only have certian energies,different elements have different energies."An atom absorbs or gives off energy(as in light or heat) the electron jumps to higher or lower orbits."He called it "stationary" orbits. -
Heisenberg and Schrodinger
http://www.pbs.org/electrons stuck in their orbits would set up "standing waves".He said that you can describe only the probiability of where an electron could be, it was not definite. Known for Schrodinger equation is "the wave equation of non relavistic quantom mechanics." He showed that waves can be used to describe electrons in atoms.(built off of Bohr's model).
