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4287 BCE
plato
Plato was a Greek philosopher born in Athens during the classical period -
460 BCE
democrius
he was a Greek philosopher. he is known for being one of the ancient atomist theory founders. -
384 BCE
aristotle
he was a Greek philosopher and polymath born during the classical period in ancient Greece. he made contributions to all philosophy and science fields he invented the field of formal logic -
The alchemists
the alchemists where viewed to manipulate the properties of matter in order to prepare more valuable substances -
lavoisier
he was a french chemist he made the discovery of the role oxygen plays in combustion he also recognized and named oxygen and hydrogen -
john dalton
he was an English chemist physicist and meteorologist he introduced atomic theory -
newtons law of octaves
In 1864, an English scientist, John Newland proposed his law of octaves where he arranged the elements in order of their atomic mass. Newland noticed that every 8th element had similar chemical properties. the properties of every eighth Element starting from any Element are a repetition of the properties of the starting Element. -
mendeleev's pd. table
the periodic table is a table full of elements with there property, function and atomic weight -
photoelectric effect
the photoelectric effect was when electrically charged particles are released from and or within a material if and when it absorbs electromagnetic radiation -
discovery of radioactivity
march 1st of 1896 Henri Becquerel Discovers Radioactivity it was an accidental discovery but it is one of the most well known on an overcast day French physicist Henri Becquerel opened a drawer and discovered spontaneous radioactivity Radioactivity demonstrated that the atom was neither indivisible nor immutable. -
robert millikan
he was an American physicist and chemist, he is known for developing the molecular orbital theory of molecular structure -
discovery of the electron
j.j Thomas founded the electron he was experimenting with other things and ended up finding electrons he also studied positively charged particles in neon gas -
discovory of the proton
the proton was discovered by Ernest Rutherford in the early 1900's his research resulted in a nuclear reaction which led to the first 'splitting' of the atom, where he discovered protons protons is based on the Greek word Protos which means first. -
planck's quantum theory
Planck's quantum theory shows the different atoms and molecules can absorb energy in discrete quantities only -
plum pudding model
the plum pudding model is a model of an atom it shows the charges and the electrons -
rutherford's gold foil experiment
the gold foil experiment is when you take a piece of gold foil and hit it with alpha particles. alpha particles have a positive charge most particles went straight through the gold foil. that showed that gold atoms were mainly empty space -
bohr's planetary model
the model is a structural atom the electrons travel around the nucleus of an atom in distinct circular orbits, or shells. Bohr was the first to discover that electrons travel in separate orbits around the nucleus and that the number of electrons in the outer orbit determines the properties of an element. -
mosley's atomic number
Mosley made a paper where he found the atomic number is the number of positive charges in the atomic nucleus he also found three unknown elements between gold and aluminum -
charge of the electron
the electron has a charge of -1 Robert Millikan discovered the charge -
heisenberg uncertainty principle
it shows that we cannot both know the position of speed and position of a particle like an electron with perfect accurate answers -
discovery of the neutron
James Chadwick found a new particle called the electron -
schrodinger equation
the Schrodinger equation is a linear partial differential equation that governs the wave function of a quantum-mechanical system. the equation describes the motion of small particles and specify's how the waves work