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400
Democritus’ -440 B.C to 360 B.C,
Demcratis was an anchient greek philsopor. He believed that matter was made up of extremely small particles. He called these particles atoms or atomos, which comes from an ancient Greek word meaning 'indivisible'. He also said bewtween them lies empy space called the void.
- first mention of atoms or atomos.
- no mentions of any atomic nucleus or its .
-no experiments he used theoretical reasoning.
-couldn't explain how atoms combined to form solids, liquids, and gases. -
Period: 400 to
Development of the Atomic Theory
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450
Aristotle (384-322 B.C.)
Aristotle was Ancient Greek philosopher. He went to Plato's academy (top class). He taught Alexander The Great himself witch gained him respect. He believed that there were only five elements: air which was light, earth which was cool and heavy, water which was wet, fire which was hot. He believed that all matter was made or of these 4 elements. Aristotle thought that no matter the number of times you cut a form of matter in half, you would always have a smaller piece of that matter. -
Jan 22, 1561
Francis Bacon
He was an english philosopher, statesman, spy, freemason and essayist. Francis Bacon is most known for seperation science and religion.Where philosophy is based on reason, faith is based on revelation, and therefore it is irrational. -
René Descartes
He is most known for his writings about science and mathematics could be used to explain everything in nature, was the first to describe the physical universe in terms of matter and motion, seeing the universe a as giant mathematically designed engine. -
Robert Boyle
Boyle mostly studied gases. He thought of the possibility of atoms existing, But his work was greatly diagreed by the church. He attempted alchemy or turning regular metals into gold. He made gas chambers to study from. Unlike the greek philosophers, he was doing physical experiments. He proposed that elements are composed of 'corpuscles' of various types and sizes that are able to organize themselves into groups that represent different chemical substances. -
Isaac Newton
He was a enlgish philosopher, He is known for being the inventor of of the teloscope. He also is famouse for his 3 laws of motion. One of his greatest experiments that he did was called the crucial experiment demonstrated his theory of the composition of light. -
William Crookes
Discovered cathode rays had the following properties: travel in straight lines from the cathode; cause glass to fluoresce; impart a negative charge to objects they strike; are deflected by electric fields and magnets to suggest a negative charge; cause pinwheels in their path to spin indicating they have mass. -
Joseph Priestly
He was an English chemist, philosopher, and Teacher. He was'nt very popular and honored as many other chemist because he belived in he theory of phlogiston until the day he died. whitch was wrong.The theory holds that all flammable materials contain phlogiston, a substance without colour, odour, taste, or mass that is liberated in burning. Once burned, the "dephlogisticated" substance was held to be in its "true" form, the calx. -
Joseph Proust's
Joseph Proust's impact on atomic theory was when he stated that a substance has the same make up where ever or how ever it was made. He discovered that the same substance found in different areas of the world had the same elements at the same ratio. He called this his Law of Definite Proportions or Proust's law. If you make water by combining hydrogen and oxygen or by decomposing hydrogen peroxide, the resulting water will still be 1 part by mass of hydrogen to eight parts by mass of oxygen. -
John Dalton
Dalton's atomic theory proposed that all matter was composed of atoms, indivisible and indestructible building blocks. While all atoms of an element were identical, different elements had atoms of differing size and mass. Dalton also stated that all compounds were composed of combinations of these atoms in defined ratios. dalton could not form atomic ratios (formulas), only mass ratios. -
Eugen Goldstein
Used a CRT to study "canal rays" which had electrical and magnetic properties opposite of an electron. -
Henri Becquerel
Henry Becquerel is known for his impact to radiation and radioactive decay. There is a term known after him called the Becquerel which is a measure of radioactive decays of a substance per second. In other words, it is the activity of the substance - the rate at which it decays -
J. J. Thomson
J. J. Thomson identified the negatively charged electron in the cathode ray tube in 1897. He determined that the electron was a component of all matter and calculated the charge to mass ratio for the electron. -
Robert Millikan
Robert Millikan 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. -
Ernst Rutherford
Ernst Rutherford braught up the nuclear atom as the result of the gold-foil experiment in 1911. Rutherford proposed that all of the positive charge and all of the mass of the atom occupied a small volume at the center of the atom and that most of the volume of the atom was empty space occupied by the electrons. -
Niels Bohr
Bohr's greatest contribution to modern physics was the atomic model. The Bohr model shows the atom as a small, positively charged nucleus surrounded by orbiting electrons. -
Erwin Schrödinger
Edwin Schrodinger stated that rather than electrons being distributed within an electron configuration of shells and energy levels, they were arranged in orbitals which were systematically distributed within Electron Clouds. He defined an orbital as: The region of space that surrounds a nucleus in which two electrons may randomly move. This represents the Quantum Model of Electrons.
