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Period: 500 BCE to 1700 BCE
The Alchemists
The Alchemists created four basic elements, fire, wind, earth, and water. They believed that everything was based off those four elements, later evolving into the periodic table. -
427 BCE
Plato
He found that there are only five solid shapes whose sides are made from regular polygons. Those shapes are triangles, squares, pentagons, hexagons etc. He was convinced that atoms of matter must derive from these five fundamental solids. -
400 BCE
Democritus
He theorized that all material bodies are made up of invisible small atoms. -
1543
Solar System Model
This model is used to arrange solar system planets in order from the sun. The Solar System Model was made by Nicolaus Copernicus. -
Robert Boyle
Boyle proposed that elements are composed of ‘corpuscles’ or various types and sizes that are able to organize themselves into groups that represent different chemical substances. He was sometimes called the Father of Chemistry due to his work on materials. -
Period: to
Antoine Lavoisier
He was a French chemist who found that the total mass of products and reactants in chemical reactions is always the same. -
John Dalton
Dalton proposed that all matter was composed of atoms, or invisible and indestructible building blocks, better known as the atomic theory. -
Billiard Ball Model
The Billiard Ball Model shows how atoms relate to billiard or pool balls because of how Dalton saw them as solid and hard spheres. This model was made by John Dalton. -
Amedeo Avogadro
He is best know for his hypothesis that equal volumes of different gases contain an equal number of molecules, provided that they are at the same temperature and pressure. -
Dimitri Mendeleev
He devised the periodic classification of the chemical elements, later classified as the periodic table. -
J.J. Thomson
His experiments with cathode ray tubes showed that all atoms contain tiny negatively charged subatomic particles or electrons. -
Plum Pudding Model
This model depicts the electrons as negatively charged particles embedded in sea of positive charge. This model was made by J.J. Thomson. -
Pierre and Marie Curie
The Curies discovered the strongly radioactive elements polonium and radium, occurring naturally in uranium minerals. -
Albert Einstein
He mathematically proved the existence of atoms. Proving to be a great contribution to the atomic theory. -
Robert Millikan
His major success was the accurate determination of the charge carried by an electron. He also proved that this quantity was a constant for all electrons, demonstrating the atomic structure of electricity. -
Ernest Rutherford
He is know for his pioneering studies of radioactivity and the atom. He discovered that there are two types of radiation, alpha and beta particles, from uranium. He also discovered that the atom consists of mostly empty space. -
Neils Bohr
He proposed and published a theory for the hydrogen atom based on the quantum theory that some physical quantities only take discrete values. This theory stated that electrons move around the nucleus but only prescribed orbits, and if electrons jump to a lower energy orbit, the difference is sent out as radiation. -
Henry G. J. Mosely
He published a paper concluding that the atomic number is the number of positive charges in the atomic nucleus. -
Erwin Schrodinger
He showed that the quantization of the hydrogen atom’s energy levels that appeared could be described by the Schrodinger equations describing how the wave function of a quantum mechanical system evolves. -
Electron Cloud Model
The Electron Cloud Model shows a particular area in which an electron is likely to be. This model was made by Erwin Schrodinger. -
Werner Heisenberg
He formulated quantum mechanics in terms of matrices. He also discovered the uncertainty principle that states that a particles position and momentum cannot both be known exactly. -
James Chadwick
He is a physicist most known for his discovery of the neutron, a particle that helps make up an atom’s nucleus.