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500 BCE
Alchemists
Alchemists layed down many parts of the basic periodic table that we know today. They broke everything up into 4 elements fire, water, earth and wind. They also developed the theory that all metals are composed out of sulfur and mercury and that they can change these base metals into gold. -
400 BCE
Ancient Greeks
“by convention bitter, by convention sweet, but in reality atoms and void”
Democritus and Leucippus are saying that everything is built up of atoms and that everything is dictated such as biter and sweet are just different structure and mixtures of atoms -
John Dalton
Dalton's theory was that all matter was created out of atoms, invisible and indestructible building blocks of life. While all elements had different and distinct atoms of different sizes. This theory was based on the law of conservation of mass. This helped with how we looked at each element and different substances and this made us look at them differently. -
J.J. Thomson
Thomson’s experiments using cathode ray tubes showed that atoms had a tiny negatively charged subatomic particles or electrons. Thomson put forward the plum pudding model of the atom, which had negatively charged electrons in a positively charged soup. although the plum pudding model is incorrect this showed that atoms had positive and negatively charged objects inside the atom. -
Marie curie
Curie found out that the number of elements present in a compound changed the amount of radiation and as it turns out it depends on the amount present. Her research helped a lot with the Manhatten project. She was also know for extracting pure radium for the first time. -
Max Planck
Planck was a german physicist who is best know as the originator of the quantum theory of energy. What he worked on contributed significantly to how we understand the atomic and subatomic processes. His work in thermodynamics also led to many formulations of his quantum theory that focuses on the nature of matter. -
Hantaro Nagaoka
Hantaro was a Japanese physicist who developed the Saturnian system. The atom as suggested in previous diagrams was inherently unstable because by radiating constantly the electron would lose energy and hit the nucleus. -
Albert Einstein
Albert Einstein came up with the theory of relativity that sought to harmonize the laws of mechanics and the laws of the electromagnetic field. His work helped establish the photon theory of light and also he proposed the theory of gravitation. -
Ernest Rutherford
Rutherford put forward that the atom is comprised of mostly empty space with electrons orbiting in a set. Predictable orbits around the positively charged nucleus at the center. -
Niels Bohr
Bohr put forward a theory about the hydrogen atom based on quantum theory transferred only in certain well-defined quantities. it talked about how electrons should move around the nucleus but only in predetermined orbits around the nucleus. -
Frederick Soddy
Soddy found that some elements have isotopes and these isotopes had different atomic weights to them. He also proposed the idea of a half-life for radioactive material. This helps with many things even today such as carbon dating and knowing how long atomic bombs will last. -
Louis de Broglie
was a French physicist who gained worldwide acclaim for his amazing work on the quantum theory. He suggested that all matter had wave-like properties and this even started a whole new branch of physics known as the wave theory. -
Satyendra Nath Bose
Bose was an Indian mathematician and physicist who helped Albert Einstein in the development of the theory regarding gas like qualities of electromagnetic radiation. -
James Chadwick
Chadwick bombarded beryllium atoms with lots of alpha particles and an unknow radiation was produced from it. He interpreted this radiation as being comprised of particles with no charge with the mass of a proton also know as the neutron today. -
Wolfgang Pauli
Pauli successfully hypothesized the existence of the neutrino as well as many physics papers and largely contributed to quantum mechanics, quantum field theory and solid-state physics. He also came up with the exclusion principle what stats that no two electrons can have the same quantum state at the same time. -
Erwin Schrödinger
Schrödinger another physicist took the Bohr model another step further. He used many math equations to describe the likelihood of finding an electron in certain positions. This atomic model is known as the quantum mechanical model. -
Werner Heisenberg
Heisenberg formulated quantum mechanics in terms of metrics as well as discovering the uncertainty principle, which says that you can not know both the position and momentum at the same time. -
Irene Joliot Curie
Curie found out that people can artificially produce radioactive elements from stable elements. This research also helped with the Manhattan project. -
Glenn Seaborg
Seaborg co-discovered 10 elements and proposed a change in the periodic tables layout to support the transuranium elements. -
Ronald Gillespie
Gillespie is known for helping Ronald Nyholm in the development of the valence shell electron pair repulsion. It’s a bunch of rules that help calculate the geometric shape of a molecule based on what it is. He also helped with the LCP theory. -
Richard Bader
Bader proposed the atoms in molecules theory and this theory tries to establish a physical base from many working theories of chemistry. Some things it helps with is atoms in molecules and bonding. For the topology of the electron function in 3D space.
