-
427 BCE
Plato
Plato postulated there has to be a fifth atomic type. -
427 BCE
Aristotle
Aristotle later called Plato's discovery of the fifth atomic type ether. -
400 BCE
Democritus
Democritus was a Greek philosopher who was
the first person to use the term atom. -
Antoine Lavoisier
Lavoisier is most noted for his discovery of the role oxygen plays in combustion. He recognized and named oxygen (1778) and hydrogen (1783), and opposed the phlogiston theory. He helped construct the metric system, he wrote the first list of elements, and helped to reform chemical nomenclature. -
John Dalton
John Dalton adapted Democritus’ theory into the first modern atomic model. -
Alchemists
The Alchemists developed practical knowledge about matter as well as sophisticated theories about it's hidden nature and transformations. -
Newlands law of octaves
Law of octaves, in chemistry, the generalization made by the English chemist states that, if the chemical elements are arranged according to increasing atomic weight, those with similar physical and chemical properties occur after each interval of seven elements. -
Mendeleev's periodic table
Mendeleev made the first periotic table in 1869. -
Photoelectric Effect
The Photoelectric Effect was discovered by German physicist Heinrich Rudolf Hertz. -
discovery of the electron
J.J Thomson was a physicist who discovered the
electron. He used his research on cathode ray tube technology in this discovery. -
Discovery of Radioactivity
Henri Becquerel Discovered Radioactivity. In one of the most well-known accidental discoveries in the history of physics, on an overcast day in March 1896, French physicist Henri Becquerel opened a drawer and discovered spontaneous radioactivity. -
Discovery of the proton
The proton was discovered by Ernest Rutherford in the early 1900's. He named his discovery “protons” based on the Greek word “protos” which means first. -
Planck's Quantum Theory of light
Planck's Quantum Theory of light states that light bulb filaments should be heated to a temperature of about 3,200 Kelvin to ensure that most of the energy is emitted as visible waves. -
plum pudding model
JJ Thompson made a model today known as the plum pudding model. -
Charge of the electron
Robert Millikan discovered the charge of an electron. -
Rutherford's gold foil experiment
Ernest Rutherford was not convinced about the model of the atom
proposed by Thomson. He then set up his now famous Gold Foil
Experiment. -
Bohr's Planetary model
Niels Bohr agreed with the planetary model of
the atom, but he also knew that it had a few
flaws. Using his knowledge of energy and
quantum physics he was able to perfect
Rutherford’s model. -
Moseley's Atomic numbers
Moseley published a paper in which he concluded that the atomic numbers is the number of positive charges in the atomic nucleus. -
Robert Millikan
Robert wins the Nobel prize for discovering the charge of an electron. -
Schrodinger Equation
The Schrodinger equation was a linear, partial, differential equation the governs the wave function of a quantum-mechanical system. -
Heisenberg uncertainty principle
Formulated by the German physicist Werner Heisenberg in 1927, 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
James Chadwick announced that the core also contained a new uncharged particle, which he called the neutron.
