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Period: 350 to
History of the Atomic Models and Scientists
A long history of the atomic model and the scientists who helped to create it. -
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Democritus
An Ancient Greek philosopher who believed all particles where made of "atomus" or atoms, which were indivisible and that there were many different kinds of atoms. He is considered to be the father of modern science. -
Antoine Lavoisier
He is most credited with creating the law of conservation of mass, or principle of mass conservation. It states that the mass of a closed system must remain constant over time. System mass cannot change quantity if it is not added or removed. The law implies that mass cannot be created or destroyed, but can be rearranged or transferred from one object to another. -
John Dalton
Created the Spherical Model and created the first Atomic Theory, stating:
-elements are made of atoms
-atoms of a given element are identical, while atoms of different elements differ in properties
-they cannot be divided, created, or destroyed
-atoms of different elements form in simple, whole-number ratios to form chemical compounds
-atoms are combined in chemical reactons -
Joseph Proust
His main contribution to the field of chemistry was his law of definite proportions. This law stated that a chemical compound always contains the exact same proportion of elements by mass. -
Eugen Goldstein
While it is debateable, he is credited with the discovery of the proton (some argue Rutherford) and the discoverer of canthode rays. He noticed the negatively charged cathode moving toward the positively charged anode. This later was recognized as the discovery of the proton. -
J. J. Thomson
He showed that cathode rays were composed of a negatively charged particle during his experiment with cathode rays, thus discovering the electron. He also create the Plum Pudding Model, which showed the electrons in a soup of positively charged "pudding" to balance out the charge. -
Hantaro Nagaoka
He developed an early planetary model of the atom. It was based as an analogy of the rings of Saturn. The model made two predictions:
-a very massive nucleus
-electrons revolve around the nucleus, bound by electrostatic forces -
Ernest Rutherford
Worked with helium ions and contributted greatly to the field of radioactivity. He created the nuclear model, which included a very small, charged nucleus and was orbited by electrons. He performed the Gold Foil Experiment, which proved the structure of the atom. -
Max Planck
He is most famous for originating quantum theory, which provided a mathmatical description of dual particle-like and wave-like behavior and interactions of energy and matter. -
Erwin Schrodinger
He helped discover results in the field of wave mechanics. He also developed the schrondinger equation to calculate stationary and time-dependent waves and further enchanced the quantum theory. Finally, he is known for creating the quantum mechanical model, which uses orbitals and volumes of space to show where there is likely to be an electron. -
Neil Bohr
Developed the Bohr Model of the atom, in which it was proposed that energy electron levels are discrete and that electrons orbit the nucleus. The element bohrium (or borium) was named after him. -
Werner Heisenburg
A German theoretical physicist, who was one of the main creators of Quantum Mechanics. In 1927, he published the uncertainty principle. It was a breakthrough, configuring a way to work with properties of a particle known as complimentary (multiple) variables. -
James Chadwick
He is most well known for his discovery of the neutron. During Chadwick's time there was speculation of a third existing subatomic particle, however finding scientific proof was not easy. After studying works in Europe, he collected proof of the neutron, founds its mass, and published its findings. This led to his modified nuclear model. It includes a nucleus with positively charged protons and neutral neutrons.
