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Timeline of the atom. SWBAT: Explain how our conceptions of the atom have changed over time by participating in a class discussion. 10/31: What evidence do we have that atoms exist?
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Timeline of the atom SWBAT: Explain how our conceptions of the atom have changed over time by participating in a class discussion. 10/31: What evidence do we have that atoms exist? Chem Trivia: The term “atom” is a misnomer. It comes from the Greek term “atomos” which means “that which can not be divided”. But we now know that atoms are made up of more fundamental particles. E?: Historically, what have we believed about the atom?
The History of Atomic Theory Atomic Structure
Atom Timeline cont.10/21: On which scientist related to the history of atoms did you do your research?Turn in your letter of recommendation for a scientist! • Chem Trivia: J.J. Thomson wanted to be a railroad engineer. Heisenberg could have become a classical pianist. He studied with one of the great Munich masters and was presenting school concerts by age 12. • SWBAT: Explain how our conceptions of the atom have changed over time by participating in a class discussion and an activity. • E?: What is the general correlation between age and scientific discoveries?
Democritus 470 BC to 380 BC He is best known for his expanding on the atomic theory of Leucippus. In this theory, Democritus says that everything is made up of atoms, even the soul. And that all of these atoms exist in an area in which all motion occurs, which is called the void or the being (space).
Dalton, John (1766-1844) • He proposed the Atomic Theoryin 1803 which stated that • (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).
JJ Thomson (1856-1940) • Used cathode ray experiments. His experiments prompted him to make a bold proposal: these mysterious rays are streams of particles much smaller than atoms, they are in fact minuscule pieces of atoms. He called these particles "corpuscles," and suggested that they might make up all of the matter in atoms. • Discovered the electron – plum pudding model of atom
Rutherford, Ernest (1871-1937) • He pioneered the orbital theory of the atom through his discovery of Rutherford scattering off the nucleus with his gold foil experiment.
The poem entitled "Version" (1962) is Frost's seemingly whimsical ode to the discovery of the nuclear atom by Ernest Rutherfordand his assistants Geiger and Marsden, an event of surpassing significance because it thoroughly revised our conception of matter. VERSION Once there was an Archer, And there was a minute When He shot a shaft On a New Departure. Then He must have laughed: Comedy was in it. For the game He hunted Was the non-existence Of the Phoenix pullet (The Mηόύ [not being] of Plato), And the shaft got blunted On her non-resistance, Like a dum-dum bullet Did in fact get splattered Like a ripe tomato. That's how matter mattered.
James Chadwick (1891-1974) • He was able to determine that the neutron did exist and that its mass was about 0.1 percent more than the proton's. He published his findings with characteristic modesty in a first paper entitled "Possible Existence of Neutron.” In 1935 he received the Nobel Prize for his discovery.
Niels Bohr (1885 – 1962) • In atomic physics, the Bohr modeldepicts 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.
Max Planck (1858-1947) • Energy does not flow in a steady continuum, but was delivered in discrete packets Planck later called quanta. He had tried to reconcile the facts with classical physics, but that hadn't worked. In fact, when people refer to "classical physics" today, they mean "before Planck."
Erwin Schrödinger (1887-1941) • Electrons behave like waves and particles • The central equation of wave mechanics, now known as the Schrödinger equation, turned out to be much simpler for physicists to solve in most cases. • Schrödinger’s cat
Werner Heisenberg (1901-1976) • Heisenberg uncertainty principle – it is impossible to measure the position and speed of an electron simultaneously • INTERVIEW • Real-Time Visualization of the Quantum Mechanical Atomic Orbitals