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500 BCE
The Alchemists
The Alchemists broke down the chemical composition of the four basic elements, Dire, Water, Earth, and Wind. Eventually, it evolved into the periodic table we use today. -
Period: 500 BCE to
Atomic Timeline
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427 BCE
Plato
Plato was a Greek philosopher who discovered that the universe is made up of atoms as well as a new form of matter called ether. -
400 BCE
Democrius
Democritus introduced the atom as the basic human building block. He also said that atoms are very small solid particles that are indestructible. -
Robert Boyle
Robert Boyle's atomic theory showed that the volume of a gas is decreased while the pressure increases proportionally. This is the understanding that gases are made of tiny particles. -
Antoine Lavoisier
Lavoisier said that matter can neither be created nor destroyed in a chemical reaction. -
John Dalton
John Dalton proposed that all matter was composed of atoms, indivisible and indestructible building blocks. Also, all atoms of an element were identical and different atoms had differing sizes and masses of atoms. -
Billiard ball Model
The Billiard Ball Mode created by John Dalton shows that atoms were the smallest particles of matter. It envisions solid hard spheres. So to describe this John Dalton used wooden balls to create a model known as the Billiard Ball Model. -
Dmitri Mendeleev
Dmitri created the periodic table. He also found the existence and properties of the new chemical elements. -
Robert Millikan
Millikan's discovery showed that fundamental electric charge is the charge of an electron. Millikan determined the mass of an electron by using charged oil drops. -
JJ Thompson
JJ Thompson wanted to explain the neutrality of atoms. He proposed a model of the atom and negative electrons core scattered throughout a sphere of positive charge. -
Henry G. J. Mosely
Henry Mosely discovered the atomic number of positive charges in the nucleus. He also found three unknown elements. -
Pierre and Marie Curie
The Curies experimented on uranium rays and discovered that was the atom's element structure. They discovered polonium and radium. -
Albert Einstein
Einstein proved that atoms existed. His theory showed that any/all liquids are made up of molecules, and are in random continual motion. -
Ernest Rutherford
Ernest Rutherford predicted the nuclear structure of the atom. Ernest discovered the scattering caused by a dense core of the atom (the nucleus). -
Neils Bohr
Neils Bohr said that electrons could only have certain classical motions. Electrons in atoms orbit the nuclear. He also said that electrons can only orbit stably without radiating in certain orbits "stationary orbits" at a certain discrete set of distances from the nucleas -
Solar System Model
The Solar System Model by Neils Bohr defines that electrons orbit around the nucleus at distances that vary. It also says that electrons in different orbits have different energies. -
Erwin Schrodinger
Erwin found that electrons absorb and release radiation of fixed wavelengths when bouncing through fixed orbits around a nucleus. -
Electron Cloud Model
The Electron Cloud Model is a model of an atom that contains a nucleus surrounded by a cloud of fast-moving electrons. It says that we can't know exactly where the electron is but are likely to be in specific areas. -
James Chadwich
James Chadwich discovered that a neutron is a particle without an electric charge with positively charged protons that make up the nucleus of an atom. -
Plum Pudding Model
The Plum Pudding Model was the first model to represent the atomic structure of matter. It is redefined by electrons surrounded by a volume of positive charge inside a positively charged "pudding".
