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Dalton Experiemnt
Idea/Experiment: He proposed an atomic theoryHow this contributed to our understanding of the atom: Dalton stated (1) all matter was composed of small indivisible particles termed atoms, (2) atoms of a given element possess unique characteristics and weight, and (3) three types of atoms exist: simple (elements), compound (simple molecules), and complex (complex molecules) -
John Dalton Elements
Six elements appear in this table, namely hydrogen, oxygen, nitrogen, carbon, sulfur, and phosphorus, with the atom of hydrogen conventionally assumed to weigh 1. -
John Dalton Atomic Theory
Elements are made of extremely small particles called atoms.
Atoms of a given element are identical in size, mass, and other properties; atoms of different elements differ in size, mass, and other properties.
Atoms cannot be subdivided, created, or destroyed.
Atoms of different elements combine in simple whole-number ratios to form chemical compounds.
In chemical reactions, atoms are combined, separated, or rearranged. -
New System of Chemical Philosophy (1808)
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JJ Thomson Experiment
In April 1897 Thomson had only early indications that the cathode rays could be deflected electrically (previous investigators such as Heinrich Hertz had thought they could not be). A month after Thomson's announcement of the corpuscle he found that he could deflect the rays reliably by electric fields if he evacuated the discharge tubes to very low pressures. By comparing the deflection of a beam of cathode rays by electric and magnetic fields he was then able to get more robust measurements of -
J.J. Thomson
Studied "canal rays" and found they were associated with the proton H + . -
JJ Thomson disycover
Used a CRT to experimentally determine the charge to mass ratio (e/m) of an electron =1.759 x 10 8 coulombs/gram. -
JJ Thomson Theory
Shortly after the discovery of the Proton, J. J. Thomson discovered the electron (which he called a 'corpuscule' at the time). Performing a similar experiment as Goldstein's, he shot a ray of charged particles through a cathode ray tube. This ray traveled from the cathode (the negatively charged end) towards the anode (the positively charged end), and deflected off of a negatively charged plate to the positively charged plate.
J. J. Thomson also invented the Plum-Pudding model. In this model, t -
Rutherford Experiments
In the early 20th century, experiments by Ernest Rutherford established that atoms consisted of a diffuse cloud of negatively charged electrons surrounding a small, dense, positively charged nucleus. -
Bohr Formulas
L=n(h/2pi)=nh -
Rutherford Cont. Experiment
Given this experimental data, Rutherford naturally considered a planetary-model atom, the Rutherford model of 1911 – electrons orbiting a solar nucleus – however, said planetary-model atom has a technical difficulty. The laws of classical mechanics (i.e. the Larmor formula), predict that the electron will release electromagnetic radiation while orbiting a nucleus. Because the electron would lose energy, it would gradually spiral inwards, collapsing into the nucleus. This atom model is disastrous -
JJ Thomson Rays
In 1912, as part of his exploration into the composition of canal rays, Thomson and his research assistant F. W. Aston channelled a stream of ionized neon through a magnetic and an electric field and measured its deflection by placing a photographic plate in its path -
Bohr Atomic theory
In atomic physics, the Bohr model, introduced by Niels Bohr in 1913, depicts the atom as a small, positively charged nucleus surrounded by electrons that travel in circular orbits around the nucleus—similar in structure to the solar system, but with electrostatic forces providing attraction, rather than gravity -
Bohr Facts
Electrons in atoms orbit the nucleus.
The electrons can only orbit stably, without radiating, in certain orbits (called by Bohr the "stationary orbits"[4]): at a certain discrete set of distances from the nucleus. These orbits are associated with definite energies and are also called energy shells or energy levels. In these orbits, the electron's acceleration does not result in radiation and energy loss as required by classical electromagnetics.
Electrons can only gain and lose energy by jumpi
