10/10/2012 1 John Dalton (1766-1844) Daniel Clark, Hazel Wertz, Cody Fletcher, Brooke Bailey Dalton’s Theory He proposed the atomic theory in 1803 which stated that all matter was composed of small indivisible particles called atoms. Atoms of a given element possess unique characteristics and weight The three types of atoms are: Simple Compound complex. 5 steps of Daltons Theory All matter consists of tiny particles Atoms are indestructible and unchangeable Elements are characterized by the mass of the atom When elements react there atom combine in simple whole number ratios When elements react there atoms sometimes combine into more then one simple whole number ratio John Dalton Daltons core theory that chemical reactions can form and separate atoms and that teach atom has a characteristic property is the foundation of modern physical science. Model of Atom This is what Dalton believed the atom looked like. Daltons Experiments 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 then developed the hypothesis that the sizes of the particles making up different gases must be different.
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10/10/2012
1
John Dalton
(1766-1844)Daniel Clark,
Hazel Wertz, Cody Fletcher,
Brooke Bailey
Dalton’s Theory� He proposed the atomic theory in 1803
which stated that all matter was composed of small indivisible particles called atoms.
� Atoms of a given element possess unique characteristics and weight
� The three types of atoms are:
� Simple� Compound� complex.
5 steps of Daltons Theory� All matter consists of tiny particles� Atoms are indestructible and
unchangeable� Elements are characterized by the mass
of the atom� When elements react there atom
combine in simple whole number ratios� When elements react there atoms
sometimes combine into more then one simple whole number ratio
John Dalton
� Daltons core theory that chemical
reactions can form and separate atoms and that teach atom has a characteristic property is the foundation of modern
physical science.
Model of Atom
� This is what Dalton believed the atom
looked like.
Daltons Experiments
� 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 then developed the hypothesis that the sizes of the particles making up different gases must be different.
10/10/2012
2
Works Cited� http://teachertube.com/viewVideo.php?title=John_Dal
� He discovered a method for separating different kinds of atoms and molecules by the use of positive rays. First to suggest that the fundamental unit was
over 1000 times smaller than an atom
Discovery
� A cathode ray tube is a fluorescent glow caused by a glass tube the has wires inserted in both ends. When air is pumped through, an electric charge is produced that causes the glow.
�He discovered electrons
Cathode Ray Tube
“J.J Thomson first experiment was to build a cathode ray tube with a metal cylinder on the end. This cylinder had two slits in it, leading to electrometers, which could measure small electric charges.
In 1897, he found that by applying a magnetic field across the tube, there was no activity recorded by the electrometers and so the charge had been bent away by the magnet. This proved that the negative charge and the ray were inseparable and intertwined.
Melanie Lippert, Kevin Dorsey, Mikayla Salazar, Jeremy Mayo
� He got his Master’s degree in physics in 1909 and his Doctor’s degree in 1911
� In 1916 he was appointed Chair of Theoretical Physics at U. of Copenhagen
� In 1922 he won the Nobel Prize in physics for his atomic structure
� In 1957 he received the first U.S. Atoms for Peace Award
Niels Bohr
� Quantum theory: Electrons travel in discrete orbit around the atoms nucleus
� Liquid Droplet theory: A liquid drop would give a very good picture of the nucleus permitted the understanding of the mechanism of nuclear fission
� You can’t move an electron a little bit, it must be moved a lot to keep it in the same order
� Uranium Isotope Fission Theory- he concluded that rare Uranium isotopes 235 were fissionable by slow neutrons while the common isotope 238 was not
Theories
� He did precise experiments on the vibrations of water jets as a way of determining surface tension
� He also sealed elemental gasses into cathode type tubes. He then electrified them, and each element fluoresced a different color. Knowing that light from the sun and from regular bulbs fluoresced white and formed a full spectrum when separated by a prism he separated the elemental light and was surprised because he only saw individual colored lines. The lines from each element were different and were like an identifying fingerprint. He called this line spectral analysis.
Experiments
� Main points of the Bohr Model:
• Electrons orbit the nucleus in orbits that have a set size and energy. • The energy of the orbit is related to its size. The lowest energy is found in the smallest orbit.
• Radiation is absorbed or emitted when an electron moves from one orbit to another.
• Where electrons orbit the nucleus in specific orbits
• Model based on an earlier theory of Rutherford's.