-
300
Democritus
Democritus was an ancient Greek philosopher who lived from 460 BC to 370 BC.Democritus claimed that everything is made up of atoms. These atoms are physically, but not geometrically, indivisible; between atoms lies empty space; atoms are indestructible; have always been, and always will be, in motion; there are an infinite number of atoms and kinds of atoms, which differ in shape, and size. -
Period: 300 to
Timeline
-
Antoine Lavoiser
Lavoisier was known for his experimentation skills. One of his favorite experiments being turing HgO into Hg+O. He used this experiment to help himself come up with the Law of Conservation. The law states that matter cannot be made or destroyed. He also hints at the rearrangement of matter in reactions. Matter rearranged, but never disappeared.He began the conversation on what an atom was exactly. -
Law of conservation of mass
Established in 1789 by French Chemist Antoine Lavoisier States that mass is neither created nor destroyed in any ordinary chemical reaction. Or more simply, the mass of substances produced (products) by a chemical reaction is always equal to the mass of the reacting substances (reactants). E.g., 1.00g carbon + 5.34g sulphur ? 6.34g carbon disulphide
and
2.00g carbon + 10.68g sulphur ? 12.68g carbon disulphide -
John Dalton
John Dalton FRS was an English chemist, meteorologist and physicist. He is best known for his pioneering work in the development of modern atomic theory, and his research into colour blindness. Wikipedia
Born: September 6, 1766, Eaglesfield, Cumbria, United Kingdom
Died: July 27, 1844, Manchester, United Kingdom -
Daltons atomic theory
Dalton's Atomic Theory
1) All matter is made of atoms. Atoms are indivisible and indestructible. 2) All atoms of a given element are identical in mass and properties 3) Compounds are formed by a combination of two or more different kinds of atoms. 4) A chemical reaction is a rearrangement of atoms. -
Dmitri Mendeleev
Dmitri Ivanovich Mendeleev was a Russian chemist and inventor. He formulated the Periodic Law, created his own version of the periodic table of elements, and used it to correct the properties of some ... Wikipedia
Born: February 8, 1834, Tobolsk, Russia
Died: February 2, 1907, Saint Petersburg, Russia -
Cathode Ray Tube
Thomson built a cathode ray tube ending in a pair of metal cylinders with a slit in them. These cylinders were in turn connected to an electrometer, a device for catching and measuring electrical charge. Perrin had found that cathode rays deposited an electric charge. Thomson wanted to see if, by bending the rays with a magnet, he could separate the charge from the rays. He found that when the rays entered the slit in the cylinders, the electrometer measured a large amount of negative charge. Th -
J.J. Thomson
Sir Joseph John "J. J." Thomson, OM, FRS was a British physicist. In 1897, Thomson showed that cathode rays were composed of a previously unknown negatively charged particle, and thus is credited with ... Wikipedia
Born: December 18, 1856, Manchester, United Kingdom
Died: August 30, 1940, Cambridge, United Kingdom -
Plum Pudding atomic model
The Plum Pudding Model is an atom model proposed by JJ Thomson, the physicist who discovered the electron. It is also known as the Chocolate Chip Cookie model.For example, you can imagine a plum pudding wherein the pudding itself is positively charged and the plums, dotting the dough, are the negatively charged electrons. -
Robert Milikan
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. Wikipedia
Born: March 22, 1868, Morrison, IL
Died: December 19, 1953, San Marino, CA -
Rutherford model
In 1909 Ernest Rutherford conducted what is now a famous experiment where he bombarded gold foil with alpha particles (Helium nuclei). A source which undergoes alpha decay is placed in a lead box with a small hole in it. Any of the alpha particles which hit the inside of the box are simply stopped by the box. Only those which pass through the opening are allowed to escape, and they follow a straight line to the gold foil -
Henry mosely
Born: November 23, 1887, Weymouth, Dorset, United Kingdom
Died: August 10, 1915, Gallipoli, Turkey.
Henry Moseley (1887-1915): A British chemist, Henry Moseley studied under Rutherford and brilliantly 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. -
The Bohr Planetary
In the Bohr Model the neutrons and protons (symbolized by red and blue balls in the adjacent image) occupy a dense central region called the nucleus, and the electrons orbit the nucleus much like planets orbiting the Sun -
Niels Bohr
Born: October 7, 1885, Copenhagen, Denmark
Died: November 18, 1962, Copenhagen, Denmark.
he studied of the structure of atoms on the basis of Rutherford's discovery of the atomic nucleus. By introducing conceptions borrowed from the Quantum Theory as established by Planck, which had gradually come to occupy a prominent position in the science of theoretical physics -
Gold Foil Experiment
This model suggested that most of the mass of the atom was contained in a small nucleus, and that the rest of the atom was mostly empty space. -
Erwin Schrodinger
Schrodinger combined the equations for the behavior of waves with de Broglie equation to generate a mathematical model is that it consists of mathematical equations known as the wave functions that satisfy the requirments placed on the behavior of electrons. -
Quantum Mechanical Model
Quantum Mechanical Model is based on quantum theory, which says matter also has properties associated with waves -
Ernest Rutherford
Earnest Rutherford publishes his atomic theory describing the atom as having a central positive nucleus surrounded by negative orbiting electrons. -
James Chadwick
James Chadwick proved the existence of neutrons, the elementary particle without any electrical charge and a fundamental building block of the atom's nucleus. -
Electron Cloud Model
The electron cloud model is an atom model wherein electrons are no longer depicted as particles moving around the nucleus in a fixed orbit.
