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410
Democritus
Democritus came up with the idea that all matter contains atoms. He reasoned that atoms were the smallest part of matter, and were indivisible. the name atom comes from the Greek word atomos which means indivisible. -
410
Aristotle
Aristotle generalized that everything was made up of four things, fire, water, air and air. -
Robert Boyle
Robert Boyle's contribution to the atomic theory was helping develope the definition of an element:any substance broken into more than 2 or more substances is not an element. -
Isaac Newton
Sir Issac Newton theorized a mechanical universe with small, solid masses in motion. -
Antoine Lavoisier
He discovered that, although matter may change its form or shape, its mass always remains the same. He recognized and named oxygen and hydrogen. -
Joseph Louis Proust
Joseph Louis Proust published his law of definite proportions stating that when compounds are analysed into their constituent parts they always contain the same proportions of their elements by weight. -
Jöns Berzelius
The chemist Jons Berzelius assumed that equal volumes of gases at the same temperature and pressure contained equal numbers of atoms. -
J,J. Thompson
J.J. Thompson discovered the electron in an experiement using the cathode ray tube. Using the tube he was able to cause non-radioactive atoms to produce streams of negatively charged particles, later named electrons. -
Ernest Rutherford
Ernest Rutherford discovered the Nucleus. He was able to do this by conducting an experiment in which he shot positvly charged particles at a very thing foil of pure gold. By doing this experiment he discovered that 1 out of 10,000 particles shot rebounded and came back. That meant that there was a positivly charged particle in the center of the atom now known as the Nucleus. -
Niels Bohr
Niehls Bohr discovered that electrons travel around an atomic nucleus in a stationary orbit.
