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3500 BCE
The Alchemists
The first alchemists were Mary the Jewess (around 0-200 CE) was the first known alchemist in history. Alchemy and it's contributions to the atomic theory By Breaking down the chemical composition of the 4 basic elements of its period, Fire, Earth, Wind, And water eventually evolved into The Periodic table we use today. Alchemy Contributed to the Atomic Theory, by laying down the foundation of the Modern Day Periodic Table of the elements. -
427 BCE
Plato
Plato theorizes that these solid forms of matter are composed of indivisible elements shaped like triangles (contrary to the popular conception of atoms as spheres). He believes triangles must be the correct form because they can join together to make very different kinds of shapes. -
400 BCE
Democritus
Democritus believed that atoms were uniform, solid, hard, incompressible, and indestructible and that they moved in infinite numbers through empty space until stopped. Differences in atomic shape and size determined the various properties of matter. -
332 BCE
Aristotle
Aristotle theory; He did not believe in atomic theory, unlike Democritus, and thought that all elements on Earth were not made of atoms except for Earth, Fire, Water and Air, themselves. Aristotle believed that all substances were made of small amounts of these four elements of matter. -
Robert Boyle
He believed that everything was composed of very tiny particles, an idea known as atomism. In this early atomic theory of Boyle, he referred to these tiny particles as corpuscles. He conducted many chemical experiments to try and understand more about the nature and behavior of these corpuscles. -
John Dalton
Dalton's atomic theory suggested that all matter was comprised of indivisible and indestructible atoms with distinct masses and properties, the combination of which determined the physical nature of their constituent elements. -
Newlands Law Of Octaves
The person who created the Newlands law of octaves is John Alexander Reina Newland also known as John newland. He found elements with similar properties occured at regular intervals, he divided the elements into seven groups of eight in what is called the "law of octives" -
Medeleev's Pd. Table
Russian chemist Dmitri Mendeleev jotted down the symbols for the chemical elements, putting them in order according to their atomic weights and inventing … the periodic table. -
photoeletric effect
physicist Heinrich Rudolf Hertz is the person who discovered this. In addition to his radio wave breakthrough, Hertz is notable for the discovery of the photoelectric effect, which occurred while he was investigating electromagnetic waves. Because of some difficulty in detecting the small spark produced in his receiving apparatus, Hertz sometimes placed the receiver in a dark case. -
Discovery of the radioactivity
the person who discovered radioactivity is Henri Becquerel. His major finding is the spontaneous emission of radiation by a material. Later, Becquerel demonstrated that the radiation emitted by uranium shared certain characteristics with X rays but, unlike X rays, could be deflected by a magnetic field and therefore must consist of charged particles. -
Planck's Quantum theory of light
the person who discovered this was Max Planck. Planck called the packets of energy quanta and he was able to determine that the energy of each quantum is equal to the frequency of the radiation multiplied by a universal constant that he derived, now known as Planck's constant. -
Plum pudding model
the person who discovered this was J.J. Thomson. his major finding was discovering the electron and then went on to propose a model for the structure of the atom. His work also led to the invention of the mass spectrograph. -
Robert Milikan
Robert Millikan succeeded in precisely determining the magnitude of the electron's charge. Small electrically charged drops of oil were suspended between two metal plates where they were subjected to the downward force of gravity and the upward attraction of an electrical field. -
Bohr's Planetary Model
The person who founded this is Niels Bohr. His major finding is he found the energy levels of electrons are discrete and that the electrons revolve in stable orbits around the atomic nucleus but can jump from one energy level (or orbit) to another. -
Futherford's Gold Foil Experiment
the person who discovered this was Ernest Rutherford. the physicist whose gold-foil experiment revealed key information about the structure of atoms -
Mosley's Atomic Numbers
This was the discovery made by Henry Gwyn-Jefferies Moseley. he observed and measured the X-ray spectra of various chemical elements using diffraction in crystals. Through this, he discovered a systematic relation between wave- length and atomic number. This discovery is now known as Moseley's Law. -
Discovery of the proton
The person who discovered the proton was Ernest Rutherford. He discovered that there are two types of radiation, alpha and beta particles, coming from uranium -
Schrodinger Equation
The person who discovered this was Erwin Schrodinger. Erwin Schrödinger showed that the quantization of the hydrogen atom's energy levels that appeared in Niels Bohr's atomic model could be calculated from the Schrödinger equation, which describes how the wave function of a quantum mechanical system (in this case, a hydrogen atom's electron) evolves. -
Hiesenburg Uncertainty Principle
the person who discovered this was laureate Werner Heisenberg. his major finding was contributed to atomic theory through formulating quantum mechanics in terms of matrices and in discovering the uncertainty principle, which states that a particle's position and momentum cannot both be known exactly. -
Discovery of the neutron
the person who discovered the neutron was physicist Sir James Chadwick. In 1927 he was elected a Fellow of the Royal Society. In 1932, Chadwick made a fundamental discovery in the domain of nuclear science: he proved the existence of neutrons – elementary particles devoid of any electrical charge.