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The alchemists thought that all metals were formed by mercury and sulfur.
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Plato introduced the theory that ideal geometric forms serve as atoms. -
Democritus found that everything was made up of atoms and he thought they were uniform, indestructible, and incompressible. -
Aristotle believed that all things were made up of fire, water, earth, and air. -
Antoine Lavoisier found how mass was conserved during chemical reactions. -
John Dalton assigned atomic weights to all the 20 elements he knew at the time. -
The founder of this was a British chemist named John Newlands. Newlands law of octaves is when elements are arranged by atomic mass every eighth element is similar.
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He created the periodic table and left gaps for elements that have not been discovered. -
Albert Einstein found that increasing the frequency of light made electrons with higher energies. -
Henri Becquerel opened a drawer and discovered spontaneous radioactivity. -
The discovery of the electron was by J. J. Thomson. He used cathode ray tubes that showed that all atoms have tiny negatively charged particles. -
According to the theory founded by Max Planck different atoms and molecules can produce or absorb small quantities of energy. -
The plum pudding model is electrons surrounded by a positive charge. The model was founded by J. J. Thompson's. -
Ernest Rutherford hit a piece of gold foil with alpha particles which have a positive charge. Most alpha particles went through this showed that gold was mostly empty space. He concluded that there was a tiny nucleus deflecting some of the alpha particles. -
The proton was discovered by Ernest Rutherford. He caused a reaction which led to the splitting of the atom where he found protons. -
Robert Millikan measured the charge of an electron using oil droplets that were negatively charged. -
He precisely found the magnitude of an electrons charge. -
In Bohr's model the electrons orbit the nucleus of the atom. This was founded by Neils Bohr. -
Henry Moseley made a paper that stated that an atomic number is the number of positive charges in the nucleus. -
It is an equation that governs the wave function of a quantum-mechanical system. Erwin Schrodinger founded the equation. -
Werner Heisenberg found that we can not know the position and speed of a particle to an exact accuracy. -
James Chadwick found the neutron by hitting beryllium with alpha particles from the natural radioactive decay of polonium. The radiation showed penetration through a lead shield which could not be explained.