Atomic Theory and Structure

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by kelly6421
Last updated 3 years ago

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Chemistry

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Atomic Theory and Structure

Atomic Theory and Structure

By Kat Schmitter and Kelly Weins

Time Line

470-380B.C

Democritis- Ancient Greek philosopher, pupil of Leucippus

1766-1844

John Dalton-English chemist, meterologist, physicist

1856-1940

JJ Thomson- British physicist

1871-1937

1885-1962

Ernest Rutherford- New Zeland born physicist and chemist(father of nuclear phisics)

Niels Bohr- Danish physicist who made foundational contributions to understanding atomic structure

-The catapult is invented by Greek engineers.

-Matter could not be divided into smaller and smaller pieces forever, eventually the smallest possible piece would be obtained. This piece would be indivisible.-To Democritus, atoms were small, hard particles that were all made of the same material but were different shapes and sizes. Atoms were infinite in number, always moving and capable of joining together.

-All matter is made of atoms. Atoms are indivisible and indestructible.-All atoms of a given element are identical in mass and properties.-Compounds are formed by a combination of two or more different kinds of atoms.-A chemical reaction is a rearrangement of atoms.-Atoms can be neither created nor destroyed.

1897- changed the view of an atom by discovering the electron. Suggests that the atom is not indivisible as it was of smaller pieces – electrons and protons.An atom consists of a sphere of positive charge with negatively charged electron embedded in it.-Plum Pudding Model-The positive and the negative charges in an atom are equal in magnitude, due to which an atom is electrically neutral. It has no over all negative or positive charge.

-First Christmas cards, and printed Valentines Day cards(1903-1904) -The first World Series is held, Boston vs. Pittsburgh -The first comic book is invented

March 7, 1911-Based on an experiment he had performed, he realized that the atom must have almost all of its mass concentrated at its center, in a nucleus, with the vast majority of the atom consisting chiefly of empty space.-it has since become known as the planetary model because electrons orbit the nucleus like planets around the Sun.

1885-World's first skyscraper built in Chicago

1913- electrons orbit the nucleus without losing energy;-could move only in fixed orbits of specific energies.-Electrons with low energy would orbit closer to the nucleus while electrons with high energy orbit further from the nucleus1924-A French physicist named Louis de Broglie suggested that, like light, electrons could act as both particles and waves.-To view an electron in its orbit, you must shine a wavelength of light on it that is smaller than the electron's wavelength.-The electron will absorb that energy.-The absorbed energy will change the electron's position.

1902-The Teddy Bear Is Introduced1903-First Message to Travel Around the World 1906-Kellogg's Starts Selling Corn Flakes

- Developed the first useful atomic theory of matter around 1803-He performed a series of experiments on mixtures of gases to determine what effect properties of the individual gases had on the properties of the mixture as a whole.-He realized the vital theoretical connection between atomic weights and weight relations in chemical reactions. He was the first to associate the ancient idea of atoms with stoichiometry.

-Mayonnaise invented -First shoes made for left and right feet

-Democritus performed no experiments and had only the flimsiest evidence for postulating the existence of atoms, his theory was kept alive by the Roman poet Lucretius which survived the Dark Ages to be discovered in 1417

-Discovered the electron in a series of experiments designed to study the nature of electric discharge in a high-vacuum cathode-ray tube, an area being investigated by numerous scientists at the time-interpreted the deflection of the rays by electrically charged plates and magnets as evidence of "bodies much smaller than atoms" that he calculated as having a very large value for the charge-to-mass ratio. Later he estimated the value of the charge itself

Quantum Theory-an electron can be viewed in two ways, either as a particle or as a wave, but never both at the same time.-this concept, which forms the basis of early quantum theory, also explains that regardless of how one views an electron, all understanding of its properties must be rooted in empirical measurement. Bohr's theory stresses the point that an experiment's results are deeply affected by the measurement tools used to carry them out-when combined with the mass and charge of the electron, produce a measure of length. Numerically, the measure is close to the known size of atoms. This encouraged Bohr to use Planck's constant in searching for a theory of the atom.

-gold foil experiment -this experiment involved the firing of radioactive particles through minutely thin metal foils (notably gold) and detecting them using screens coated with zinc sulfide (a scintillator). Rutherford found that although the vast majority of particles passed straight through the foil approximately 1 in 8000 were deflected leading him to his theory that most of the atom was made up of 'empty space'.


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