Atomic Theory
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Transcript of Atomic Theory
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Atomic TheoryThe Movers and Shakers of the Subatomic World.
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DaltonIn the early 1800s, the English chemist John Dalton did a number of experiments that eventually led to the acceptance of the idea of atoms.
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Daltons Atomic TheoryAll elements are composed of atoms. Atoms are invisible and indestructible particles.
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continued...Atoms of the same element are exactly alike.
HH
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continued...Atoms of different elements are different.
O H
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continued...Compounds are formed by the joining of atoms of two or more elements.
H H O
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Questions...What were the four parts of the Daltons atomic theory?Say it again...
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Was he right?Daltons atomic theory of matter became one of the foundations of chemistry.BUT it needed workother scientists had to modify the theory.
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ThomsonIn 1897, the work of an English scientist J. J. Thompson provided the first hint that atoms were made up of even smaller particlesAtoms are divisibleDalton was wrong!
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Thompsons ModelHe stated that atoms are made up of positively (+) and negatively (-) charged particles
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And...He thought the positive (+) and negative (-) particles were s p r e a d o u t in atoms like p p u l d u d m i s n
(plums in puddin)
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Questions...What kind of particles did Thompson find in atoms?What did his idea of an atom look like?
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Was Thomson Right?Not reallythere are positively (+) and negatively (-) charged particles inside atoms.BUT...
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Rutherfords ModelIn 1908, Rutherford discovered the nucleus.He stated that atoms have a small, dense, positively (+) charged center called a nucleus.
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Questions...What did Rutherford find inside the atom?What did Rutherfords atom look like?
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So...Particles are not spread out like plums in puddingPositive particles (protons) are in the center (nucleus).Where are the negative particles (electrons)?
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Bohrs ModelIn 1913, Niels Bohr proposed an improvement to Rutherfords Model:Electrons move in definite orbits around the nucleus, like planets around the sun.
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Questions...What did Bohr propose?Where were the particles in Bohrs model of an atom?What did it look like?What was special about the electrons in Bohrs model?
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Are we there yet?Bohrs model was used for a long time
BUT...
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Modern Atomic ModelAn atom has a small, positively charged nucleus surrounded by a large region in which there are enough electrons (-) to make the atom neutral (0).
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PEEEEEEEEEEEPPPPPPPPPPPE
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Questions...Do electrons have specific orbits in the modern model?What does the atom look like in the new model?
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Make Your TimelineAfter the sheet is passed out:write your name on it!Fill out the timeline according to date, scientist, notes, and picture (if there is one) for each scientist we went over.Neatness counts!!!!!HAVE FUN