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440 BCE
plato atomic theory
Plato believed that atoms were composed of invisible elements shaped as triangles and were solid forms of matter -
400 BCE
Democritus' atomic theory
Democritus believed that atoms were hard, solid indestructible and uniform and moved in infinite numbers -
332 BCE
Aristotle's atomic involvement
he did not believe in the atomic theory like Democritus, he believed things were not made of atoms but rather out of four elements, earth, water, fire and air -
Robert Boyle
Robert discovered that the volume of gas decreases with an increase in pressure and the volume increases with a decrease in pressure -
john dalton atomic theory
John Dalton's atomic theory stated that all matter is made up of indivisible atoms and atoms of the same element are identical. -
the alchemists atomic theory
the alchemists believed that all metals were formed in mercury and sulfer -
newland's laws of octaves
created sorting and arranging them by an increasing level of atomic mass. it's also sorted to be that the properties of the first -
Mendeleev's Periodic table
Mendeleev organized the elements in a brand new way -
photoelectric effect
it's an event that happens when a light is shoe onto a metal surface or object that causes a ejection of electrons from the metal -
discovery of radioactivity
Henri Becquerel started with a wrong idea but ended up beginning to discover the radioactivity of uranium -
planck's quantum theory of light
Planck proposed light's energy had a frequency creating Planck's constant. -
plum pudding model
J.J. Thompson, said that the electrons were stuck in a sphere that was of positive charge -
robert millikan
Robert Millikan measured the charge of an electron. He accomplished this by using oil drops each carrying an electric charge between two metal plates. With accuracy he determined the amount of electric charge carried by small oil droplets by carefully balancing the forces of gravity and electricity. -
Rutherford's gold foil experiment
Rutherford shoots a beam of alpha particles at a sheet of gold foil and noted that a tiny dense nucleus was causing deflections -
bhor's planetary model
it says that electrons orbited around the nucleus of the atom much like planets orbiting the sun -
mosleys atomic numbers
Mosley posted up a paper that said that the atomic number is the number of positive charges. he also said there were mystery number 43,61,75 -
discoevry of the proton
Ernest Rutherford observed that his scintillation detectors saw hydrogen nuclei when a beam of alpha particles was shot into the air -
schrodinger equation
the Schrodinger equation measured probabilities in waves that are the govern of small particles and in specifics defines how the waves are altered on an external level -
Heisenberg uncertainty principle
Heisenberg noted that we will never know the position and speed of a particle such as a photon or electron with perfect accuracy -
discovery of the neutron
James Chadwick discovered the Neutron by firing alpha particles at beryllium using a polonium source