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Dead Dudes Project
Transcript of Dead Dudes Project
• Matter is composed of small particles called atoms.
• Atoms are indivisible & indestructible.
• Atoms of a given element are identical in mass and chemical properties.
• Different atoms combine in simple whole # ratios to form compounds.
• Atoms are separated, combined or rearranged in a chemical reaction. (1856-1940) J.J Thomson Cathode Ray: Thomson came up with the initial idea for the structure of the atom, postulating that it consisted of these negatively charged particles swimming in a sea of positive charge. His pupil, Rutherford, developed the idea and came up with the theory that the atom consisted of a positively charged nucleus surrounded by orbiting tiny negative particles, which he called electrons.
Plum Pudding Model: In 1911, Ernest Rutherford performed an experiment to test the plum pudding model. He fired energetic a [He2+] particles at a foil, and measured the deflection of the particles as they came out the other side. From this he could deduce information about the structure of the foil. If the mound were made of loose, powdery snow, the bullets would be deflected very little; if the bullets were deflected wildly, we might guess that there was a brick of hard material inside.
Rutherford expected all of the particles to be deflected just a bit as they passed through the plum pudding. Occasionally, however, particles were scattered at huge angles. While most of the a’s were undisturbed, a few of them bounced back directly. With this experiment, Rutherford discovered the nucleus. (1871-1937) Ernest Rutherford Gold Foil Experiment: In 1911, Ernest conducted experiments in which he aimed a beam of alpha particles (positively charged helium nuclei) at thin sheets of gold. The fact that a few particles were deflected almost directly backwards revealed that the positive charge of an atom, along with nearly all of the atom’s mass in concentrated in s very small region in the center of the atom, the nucleus. (1885-1962) Niels Bohr In 1913 Bohr proposed his quantized shell model of the atom to explain how electrons can have stable orbits around the nucleus. The motion of the electrons in the Rutherford model was unstable because, according to classical mechanics and electromagnetic theory, any charged particle moving on a curved path emits electromagnetic radiation; thus, the electrons would lose energy and spiral into the nucleus. To remedy the stability problem, Bohr modified the Rutherford model by requiring that the electrons move in orbits of fixed size and energy. The energy of an electron depends on the size of the orbit and is lower for smaller orbits. Radiation can occur only when the electron jumps from one orbit to another. The atom will be completely stable in the state with the smallest orbit, since there is no orbit of lower energy into which the electron can jump.
He received the Nobel Prize for Physics in 1922. Bohr's Model of the Atom (1887-1961) Erwin Schrodinger In 1935, Erwin Schrödinger attempted to criticize the Copenhagen Interpretation with and illustrated example of a cat in a box that aimed at the explanation of the paradoxical nature of the theory.
Imagine a steel chamber in which there is a cat on one side and on the other side of a partition there is a device with deadly poison. If even a single atom of the poison decays during the test period, the device will release the poison and kill the cat. The observer cannot know whether or not an atom of the substance has decayed, and can't know if the cat is dead or alive. Rather than successfully critiquing the Copenhagen Interpretation, he showed that according to quantum law, the cat is both dead and alive. Only when the chamber is opened does the cat become either dead or alive. Therefore, things exist in a state of equanimity until an observer imposes a defined state of being. Schrodinger Model (1834-1907) Dmitry Mendeleev In 1914, Henry Moseley learned you could experimentally determine the atomic numbers of elements. Before that, atomic numbers were just the order of elements based on increasing atomic mass. Mendeleev's table was also based upon his Periodic Law, which stated that when elements are arranged by increasing atomic number, there is a periodic repetition of similar chemical and physical properties. Once atomic numbers had significance, the periodic table was reorganized, and it was no longer placed by increasing atomic mass, even though it may seem like it.
3 main ideas:
1.They were grouped into columns called periods.
2. They were grouped into rows called groups or families.
3. The atomic weight differed between the elements. Henry Moseley (1887-1915) In 1914, Henry Moseley learned you could experimentally determine the atomic numbers of elements. Before that, atomic numbers were just the order of elements based on increasing atomic mass. Mendeleev's table was also based upon his Periodic Law, which stated that when elements are arranged by increasing atomic number, there is a periodic repetition of similar chemical and physical properties. Once atomic numbers had significance, the periodic table was reorganized, and it was no longer placed by increasing atomic mass, even though it may seem like it. "Modern Day" Periodic Table