Chemists of the Atom

By Hovhannes Aklyan, Period 6



460 BC - 370 BC

Democritus believed that all matter is made up of tiny, indestructible bits which he called atoma (atomos for plural) or "indivisible units", from which we get the English word atom.


1731 - 1810

Cavendish discovered Hydrogen (H).


1754 - 1826

Proust’s largest accomplishment was creating elements from water. Proust made artificial elements.


1766 - 1844

John Dalton developed the atomic theory.


1778 - 1850

Gay-Lussac formulated two gas laws. Discovered the element boron. Devised a measure of alcohol by volume, which came to be termed degrees Gay-Lussac. Gay-Lussac found that when you mixed hydrogen and oxygen, you got water. For every volume of oxygen, it took two of the same volume of hydrogen to complete the reaction. Further investigation found this true for many other gas reactions.


1834 - 1907

Mendeleev formed the Periodic table by arranging the elements in the order of increasing atomic mass. The columns reflected uniform trends in their chemical properties.


1856 - 1940

Thompson created a model known as the "Plum Pudding Model". He stated that the atom was a positively charged atom with negative particles in it. He called them electrons.


1858 - 1947

Plank's quantum theory basically says that radiant energy can only be emitted or absorbed in discrete quantities, like small packages or bundles. He gave the name quantum to the smallest quantity of energy that can be emitted (or absorbed) in the form of electromagnetic radiation. E = hν. E is the energy of a single quantum and v (which is the greek symbol nu) is the frequency of the radiation and h is Plank's constant (6.63 x 10-34 J s).


1865 - 1950

Nagaoka rejected Thomson's model on the ground that opposite charges are impenetrable. He proposed an alternative model in which a positively charged center is surrounded by a number of revolving electrons, in the manner of Saturn and its rings.


1871 - 1937

Rutherford was a brilliant scientist who, among other things, discovered what was inside an atom, putting paid to the previously accepted "plum pudding" model. By setting up a classic experiment involving gold foil and an alpha particle emitter, he noticed that atoms consisted of a dense central region (the nucleus), which possessed a positive charge.


1885 - 1962

Bohr helped discover quantum physics, the structure of the atom, and the atomic bomb. Bohr was awarded the Nobel Prize in 1922 for, in short, discovering the quantization of atomic energy levels. he published his theory of electrons. He introduces the theory of electrons traveling in orbits around the nucleus of the atom in 1913 and the chemical properties of the orbit. He introduced the idea that an electron can drop from a higher energy orbit to a lower one. Then it can emit a photon of discrete energy. This is the basis of quantum theory.


1891 - 1974

Chadwick discovered the neutron (sub-atomic particle with no charge).


1903 - 1930

Ramsey looked to the experiments conducted by Cavendish 100 years ago. He left his mark not solely on philosophy (especially philosophical logic, probability theory and attempts to derive mathematics from logic), but also on economics and mathematics proper.