-
490 BCE
Democritus
He developed the concept of the atom. A Molecular Dynamics simulation. About 400 B.C. the Greek philosopher Democritus suggested that all matter was formed of different types of tiny discrete particles and that the properties of these particles also determined the properties of matter. -
330 BCE
Aristotle
He didn't believe in Atomic theory, He thought that all things weren't made of atoms but of the 4 elements -
Antoine Lavoisier
The first breakthrough in the study of chemical reactions resulted from the work of the French chemist Antoine Lavoisier. -
Joseph Proust
He was best known for his discovery of the law of constant composition in 1794 -
John dalton
he identified the hereditary nature of red-green color blindness. In 1803 he revealed the concept of Dalton's Law of Partial Pressures. All things are made of atoms. All atoms of a given element are identical. Atoms cannot be divided created or destroyed. Atoms combined in whole number ratios to form compounds. In chemical reactions atoms are combined,separated or rearranged -
JJ Thomson
Thomson discovered the electron by experimenting with a Crookes, or cathode ray, tube. He demonstrated that cathode rays were negatively charged. In addition, he also studied positively charged particles in neon gas. -
Ernest Rutherford
A pioneer of nuclear physics and the first to split the atom, Rutherford was awarded the 1908 Nobel Prize in Chemistry for his theory of atomic structure. Dubbed the “Father of the Nuclear Age,” Rutherford died in Cambridge, England, on October 19, 1937 of a strangulated hernia. -
Robert Milikan
determined the unit charge of the electron in 1909 with his oil drop experiment at the University of Chicago. Thus allowing for the calculation of the mass of the electron and the positively charged atoms. -
Niels Bohr
proposed a theory for the hydrogen atom based on quantum theory that energy is transferred only in certain well defined quantities. Electrons should move around the nucleus but only in prescribed orbits. When jumping from one orbit to another with lower energy, a light quantum is emitted. -
Schrodiner & Heisnberg
an Austrian physicist, took the Bohr atom model one step further. Schrödinger used mathematical equations to describe the likelihood of finding an electron in a certain position. This atomic model is known as the quantum mechanical model of the atom. -
James Chadwick
James Chadwick announced that the core also contained a new uncharged particle, which he called the neutron.