-
400
Democritus
Formulated atomic theory in 400 B.C. -
Antoine Lavoisier
He named both oxygen (1778) and hydrogen (1783) and Helped construct the metric system, put together the first extensive list of elements, and helped to reform chemical nomenclature. He was also the first to establish that sulfur was an element rather than a compound.[3] He discovered that, although matter may change its form or shape, its mass always remains the same. -
Law of Conservation of mass
Discovered by Antoine Lavoisier. States that all mass is neithier created nor destroyed in a chemical reaction. -
John Dalton
Did alot of research on colorblindness. Came up with some ideas in the atomic theory. Developed "Gas laws." Suggested that different atoms combine in simple whole number ratios to form compounds. -
Dalton's Atomic Theory
His theory is that:
1.All matter is composed of extremely small particles called atoms.
2.All atoms of a given element are identical, having the same size,mass,and chemical properties.
3. Atoms cannot be created, divided into smaller particles, or destroyed.
4. Different atoms combine in simple whole number ratios to form compunds.
5. In a chemical reaction, atoms are seperated, combined, or rearranged. -
Dmitri Mendeleev
He is credited as being the creator of the first version of the periodic table of elements. Using the table, he predicted the properties of elements yet to be discovered. -
J.J. Thomson
Discovered electrons through experiments using the cathode ray tube. -
Cathode Ray Tube
The first cathode ray tube scanning device was invented by the German scientist Karl Ferdinand Braun. -
Plum Pudding Atomic Model
Intoduced by J.J. Thomson, during the Gold Foil Experiement. -
Gold Foil Experiment
Experiment to probe the structure of the atom performed by Hans Geiger and Ernest Marsden. -
Robert Millikan
Determined the mass of an electron is 9.1 times 10 to the negative 28 power or 1/1840 mass of a hydrogen atom. -
Rutherford Model
Discovered protons, positevly charged particles using the Gold Foil Experiment. Determined that the atom was made of mostly empty space through which electrons moved. -
Ernest Rutherford
Discovered protons. -
Bohr Planetary Model
Introduced by Niels Bohr , depicts the atom as a small, positively charged nucleus surrounded by electrons that travel in circular orbits around the nucleus. -
Henry Moseley
Developed the application of X-ray spectra to study atomic structure; Moseley's discoveries resulted in a more accurate positioning of elements in the Periodic Table by closer determination of atomic numbers. -
Niels Bohr
Awarded the Nobel Prize in physics. Was the first to apply the quantum theory, which restricts the energy of a system to certain discrete values, to the problem of atomic and molecular structure. -
Erwin Schrodinger
Developed a powerful model of the atom .Developed a number of fundamental results in the field of quantum theory, which formed the basis of wave mechanics: he formulated the wave equation (stationary and time-dependent Schrödinger equation) and revealed the identity of his development of the formalism and matrix mechanics. -
Electron Cloud Model
It was developed by Ernest Schodinger and Werner Heisenberg.The cloud model represents a sort of history of where the electron has probably been and where it is likely to be going. The red dot in the middle represents the nucleus while the red dot around the outside represents an instance of the electron. -
Quantum Mechanical Model
Constucted by Erwin Scrodinger and is based on mathematics. The quantum mechanical model is based on quantum theory, which says matter also has properties associated with waves. -
James Chadwick
Discovered the neutron has no charge and is founfdcin the nucleus.
