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John Dalton
Experiment: Took two substances and reacted them together to produce another substance. Also found that different ratios could produce different things.
Used the Law of Multiple Proportions and the Law of Conservation of Mass to deduce that there must be some "fundamental indivisible particle." -
JJ Thomson
Discovered negatively charged electrons with cathode ray tube experiment
Discovered that neutrons were negatively charged using a positively charged metal plate to curve the cathode ray. Which is evidence that the electron is negatively charged because they're attracted to each other. He used different types of metal plating just to prove that his theory was correct. -
Ernest Rutherford
Experiment: Took a piece of gold foil and shot alpha particles at it to prove that the atom is mostly empty space.
Majority of the particles went straight through the foil, but some were bounced back due to them hitting the center of the atom.
Proved that the electrons are moving around the nucleus instead of being stuck inside. -
Niels Bohr
Proved the different power levels that electrons are found in. If they were randomly floating around the nucleus, they would eventually run out of energy and fall into the nucleus, destroying the atom.
It's impossible for electrons to exist out of said levels. -
James Chadwick
Discovered the neutron to be in the center of the atom. Was also able to explain the existence of isotopes through his discovery of the neutron.
Isotopes are two or more forms of the same element that contain an equal number of protons, but different numbers of neutrons. Meaning they differ in atomic mass, but not in chemical properties.
