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400 BCE
Democritus
Democritus, was very influential for his time. Many still believed that the world was made up of the four elements, meaning earth, air, wind and fire. Democritus however had an idea that all life is made up of small particles and attempted to prove this. So he conducted experiments, namely, he took small seashells and broke them in half, repeatedly until a fine powder was created and could no longer be broken. This proved his atomic theory that wouldn't be accepted till much later. -
John Dalton
The obvious creator of Dalton's law, John Dalton had discovered that atoms behaved different depending on the weight. This meant that different pressures were present depending on the heavy or lightness of the object. He did so by experimenting on many gases Including hydrogen. He did this by testing displacement in water and discovered that while something can have no water inside, if weighed down enough, the displacement of the water will happen causing the empty object to fill with hydrogen. -
Ernest Ruthford
Ernest Ruthford had been very influential to the atomic theory as well. Through experiments he had single handedly discovered alpha rays as well as beta rays. He even went as far as to discover that atoms had amounts of nuclear radiation as well as had a core that he named the Nucleus. He came to these conclusions by firing energetic particles at a foil, and measured the deflection of the particles as they arrived from the opposite side. -
J.J. Thomson
J.J. Thomson was possibly just as influential to the understanding of the atom as Democritus. J.J. had discovered the electron, through no other means than experimentation as most scientists do. The discovery of the electron was accomplished by proving that charged particles or electrons would be propelled back by magnetic fields. He tested this by producing magnetic fields and then reading the mass to charge ratio of the rays he called cathode rays. -
Niels Bohr
Niels Bohr had discovered many ideals about the atomic theory that furthered the understanding of the substance that makes up the world. He had discovered, again, through experimentation that energy from atoms and particles could be transferred, however in a small quantity. He also had created the Bohr model of the atom. He found this fact of life by measuring the energy levels in the electrons of the atom.
