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John Dalton
John Dalton thought that the atom was a result of dividing a compound until it could no longer be divided. He determined the structure of the atom to be a hard indivisible sphere -- and that all atoms of an element were identicle -
J.J. Thompson
J.J. Thompson was working with discharge tubes (like neon lights) and discovered that he could bend the light within the tube and determined it to have a negative charge. He assumed there to be a very light negatively charged particle floating at random within a charged matrix. This gave way to the plumb pudding model! -
Ernest Rutherford
Rutherford used experimentation based upon previous knowledge and determined that the positive charge was concentrated in the middle of the atom. He called this an atoms Nucleus. He also found that the atom was mostly empty space where electrons moved. These positively charged particles he called Protons and the otehr neutral particles he names neutrons. -
Niels Bohr
Bohr studied with Rutherford and together they determined the arrangement of electrons. Bohr discovered the existence of energy levels or shells. Each energy level can have a specific number of electrons. This became known as the planetary model. -
Erwin Schrödinger
Schrödinger discovered what we typically understand today as the best representation of the atom. He determined that electrons actually act as waves and exist in probability clouds or more recognizably named orbitals. This helped us describe bonding between elements as well as several other phenomena.