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460 BCE
democrtus
Democritus was an Ancient Greek pre-Socratic philosopher from Abdera, primarily remembered today for his formulation of an atomic theory of the universe. None of his work has survived -
429 BCE
plato
Plato was an ancient Greek philosopher born in Athens during the Classical period. In Athens, Plato founded the Academy, a philosophical school where he taught the philosophical doctrines that would later become known as Platonism. -
332 BCE
Aristotle
As the father of western logic, Aristotle was the first to develop a formal system for reasoning. He observed that the deductive validity of any argument can be determined by its structure rather than its content, for example, in the syllogism: All men are mortal; Socrates is a man; therefore, Socrates is mortal. -
399
the alchemists
Alchemists laid the groundwork for many chemical processes, such as the refining of ores, the production of gunpowder, the manufacture of glass and ceramics, leather tanning, and the production of inks, dyes, and paints. -
robert boyle
Every general-chemistry student learns of Robert Boyle (1627–1691) as the person who discovered that the volume of a gas decreases with increasing pressure and vice versa—the famous Boyle's law. A leading scientist and intellectual of his day, he was a great proponent of the experimental method. -
john dalton
John Dalton FRS was an English chemist, physicist and meteorologist. He is best known for introducing the atomic theory into chemistry, and for his research into colour blindness, which he had. Colour blindness is known as Daltonism in several languages, being named after him. -
mendeleevs pd table
Dmitri Ivanovich Mendeleev was a Russian chemist and inventor. He is best known for formulating the Periodic Law and creating a version of the periodic table of elements. -
Newland's Law of Octaves
Newland's Law of Octaves states that when Elements are arranged in increasing order of Atomic Mass, the properties of every eighth Element starting from any Element are a repetition of the properties of the starting Element. Law of Octaves was true only for Elements up to Calcium. -
The photoelectric effect
The photoelectric effect is the emission of electrons when electromagnetic radiation, such as light, hits a material. Electrons emitted in this manner are called photoelectrons. -
discovery of radioactivity
Abstract. The radioactivity of uranium was discover by Henri Becquerel who, starting from a wrong idea, progressively realized what he was observing, regularly informing the French Academy of Sciences of the progress he was doing. -
planck quantum theory of light
Planck proposed that the energy of light is proportional to frequency, and Planck's constant (h) is the constant that relates them. Albert Einstein determined that light is made up of discrete quanta of energy called photons as a result of his research. -
plum pudding model
In Thomson's plum pudding model of the atom, the electrons were embedded in a uniform sphere of positive charge, like blueberries stuck into a muffin. The positive matter was thought to be jelly-like, or similar to a thick soup. The electrons were considered somewhat mobile. -
rutherford gold foil experiment
The Geiger–Marsden experiments were a landmark series of experiments by which scientists learned that every atom has a nucleus where all of its positive charge and most of its mass is concentrated. They deduced this after measuring how an alpha particle beam is scattered when it strikes a thin metal foil. -
bohr's planetary model
According to the Bohr model, often referred to as a planetary model, the electrons encircle the nucleus of the atom in specific allowable paths called orbits. When the electron is in one of these orbits, its energy is fixed. -
moseley atomic number
published a paper in which he concluded that the atomic number is the number of positive charges in the atomic nucleus. He also stated that there were three unknown elements, with atomic numbers 43, 61, and 75, between aluminum and gold. -
discovery of proton
The discovery of the proton is credited to Ernest Rutherford, who proved that the nucleus of the hydrogen atom -
The Schrödinger equation
The Schrödinger equation is a linear partial differential equation that governs the wave function of a quantum-mechanical system. Its discovery was a significant landmark in the development of quantum mechanics. -
heisenberg uncertainty principle
, the uncertainty principle states that we cannot know both the position and speed of a particle, such as a photon or electron, with perfect accuracy; the more we nail down the particle's position, the less we know about its speed and vice ... -
discovery of the neutron
ames Chadwick announced that the core also contained a new uncharged particle, which he called the neutron. -
robert millikan
Robert Andrews Millikan was an American experimental physicist who won the Nobel Prize for Physics in 1923 for the measurement of the elementary electric charge and for his work on the photoelectric effect. Millikan graduated from Oberlin College in 1891 and obtained his doctorate at Columbia University in 1895