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The Alchemists proposed that all metals were formed of sulfur and mercury in different proportions. This ended up being false, but this was important because it started a conversation about what makes up matter. -
Plato said that all matter is a copy of an "ideal form" that is unchanging. He also said that matter could be divided into smaller and smaller units infinitely. -
Democritus formed a hypothesis about the universe, he posed that everything was made up of atoms. -
Robert Boyle demonstrated that matter is made up if smaller particles. These particles are now known as atoms. -
Antone Lavoisier discovered oxygen and named it. He also studied how it behaves and combusts. -
John Dalton discovered that each element had its own unique kind of atom. -
The Billiard Ball Model was the first atomic model created by John Dalton. It shows how atoms join together to form molecules. -
Amadeo Avogadro posed that equal volumes of gasses will contain the same number of molecules. -
Dmitri Mendeleev created the first version of the periodic table of elements. -
JJ Thompson discovered the electron, which was the first subatomic particle to be found. -
Pierre and Marie Curie confirmed that some elements were radioactive. And discovered multiple new elements. -
The Plum Pudding Model was created by JJ Thompson, it showed the "pudding" as the positive charged atom, and the "plums" in the pudding as the negative charged electrons. -
Albert Einstein Mathematically proved the existence of atoms. -
Robert Millikan discovered electrons. And measured the charge of an electron. -
The Solar System Model was created by Ernest Rutherford and it shows the nucleus int the center (like the sun) surrounded by electrons (like planets orbiting the sun). -
Henry G.J. Mosely justified the concept of the atomic mass of elements. -
Neils Bohr made an atomic model where the electrons surround the nucleus. -
Ernest Rutherford discovered the proton and developed an atomic numbering system. He also discovered radioactive half-life which is a way to figure out how old rocks and minerals are. -
The Electron Cloud Model shows a nucleus in the middle and a cloud of energy (electrons) surrounding it. -
James Chadwick was the first person to discover the neutron. -
Erwin Schrodinger advanced the field of quantum mechanics and wave theory (how subatomic particles function).
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