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Democritus
Greek philosopher who developed an atomistic theory of matter. -
Antoine Lavoisier
French chemist known as the father of modern chemistry; discovered oxygen and disproved the theory of phlogiston -
Law of Conservation of Mass
A fundamental principle of classical physics that matter cannot be created or destroyed in an isolated system -
John Dalton
English chemist and physicist who formulated atomic theory and the law of partial pressures; gave the first description of red-green color blindness -
Dalton's Atomic Theory
The theory that matter consists of indivisible particles called atoms and that atoms of a given element are all identical and can neither be created nor destroyed. -
Dmitri Mendeleev
Russian chemist who developed a periodic table of the chemical elements and predicted the discovery of several new elements. -
Cathode Ray Tube
A high-vacuum tube in which cathode rays produce a luminous image on a fluorescent screen, used chiefly in televisions and computer terminals. -
JJ Thomson
In 1897, Thomson showed that cathode rays were composed of a previously unknown negatively charged particle, and thus is credited with the discovery and identification of the electron. -
Plum Pudding Atomic Model
Proposed in 1904 before the discovery of the atomic nucleus in order to add the electron to the atomic model. In this model, the atom is composed of electrons though G. J. Stoney had proposed that atoms of electricity be called electrons in 1894[1]) surrounded by a soup of positive charge to balance the electrons' negative charges, like negatively charged "plums" surrounded by positively charged "pudding". -
Robert Millikan
Robert A. Millikan was an American experimental physicist honored with the Nobel Prize for Physics in 1923 for his measurement of the elementary electronic charge and for his work on the photoelectric effect. -
Rutherford Model
The Rutherford model is a model of the atom devised by Ernest Rutherford. Rutherford directed the famous Geiger-Marsden experiment in 1909 which suggested, upon Rutherford's 1911 analysis, that the so-called "plum pudding model" of J. J. Thomson of the atom was incorrect. -
Henry Moseley
Henry Gwyn Jeffreys Moseley was an English physicist. Moseley's outstanding contribution to the science of physics was the justification from physical laws of the previous empirical and chemical concept of the atomic number. This stemmed from his development of Moseley's law in X-ray spectra. -
Bohr Planetary
An early model of atomic structure in which electrons travel around the nucleus in a number of discrete stable orbits determined by quantum conditions. -
Niels Bohr
Danish physicist who studied atomic structure and radiations; the Bohr theory of the atom accounted for the spectrum of hydrogen (1885-1962) -
Gold Foil Experiment
The Geiger–Marsden experiment was an experiment to prove the structure of the atom performed by Hans Geiger and Ernest Marsden in 1909, under the direction of Ernest Rutherford at the Physical Laboratories of the University of Manchester. -
Erwin Schrodinger
Austrian physicist who discovered the wave equation (1887-1961) -
Quantum Mechanical Model
Quantum mechanics is a branch of physics which deals with physical phenomena at microscopic scales, where the action is on the order of the Planck constant. Quantum mechanics departs from classical mechanics primarily at the quantum realm of atomic and subatomic length scales -
Ernest Rutherford
British physicist (born in New Zealand) who discovered the atomic nucleus and proposed a nuclear model of the atom (1871-1937) -
James Chadwick
Sir James Chadwick CH FRS was an English physicist who was awarded the 1935 Nobel Prize in physics for his discovery of the neutron in 1932. He was the head of the British scientists who worked on the Manhattan Project during World War II. He was knighted in 1945 for achievements in physics. -
Electron Cloud Model
Atoms consist of a "cloud" of fast moving, negatively charged electrons surrounding a tiny, extremely dense nucleus containing positively charged protons and neutral neutrons. The nucleus contains virtually all of the atom's mass, but occupies only about one ten-thousandth the volume of the atom.
