Unit 3 part 1

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Unit 3part 1

• Atomic Theory

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EQ

• How does knowing the history of the development
  of the atomic theory shape our present
  understanding of the composition behavior of
  atoms?

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GPS

• SC3. Students will use the modern atomic theory
  to explain the characteristics of atoms.
• a. Discriminate between the relative size,
  charge, and position of protons, neutrons, and
  electrons in the atom.
• c. Explain the relationship of the proton number
  to the elements identity.
• d. Explain the relationship of isotopes to the
  relative abundance of atoms of a particular
  element.

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History of the atoms

1. Matter is composed of empty space through which
   atoms move
2. Atoms are solid, homogeneous, indestructible, and
   indivisible
3. Different kinds of atoms have different sizes and
   shapes
4. Differing properties are due to the size, shape
   and movement of atoms
5. Changes in matter result from the changes in
   groupings of atoms

• Matter is composed of air, fire, water, and Earth
• His popularity allowed his ideas to persist into
  the 1800s.

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• Daltons Atomic theory
• All matter is composed of extremely small
  particles called atoms
• All atoms of a given element are identical
• Atoms can not be created, divided, or destroyed
  (Law of Conservation of Mass)
• Different atoms combine in simple whole number
  ratios to form compounds (Law of Definite
  Proportions)
• In a chemical reaction, atoms are separated,
  combined, or rearranged

Unlike Democritus, Dalton proved his ideas with
science experiments. Known for the atomic theory
we use today.
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Subatomic Particles

• JJ Thomson
• Found charge to mass ratio of electron
• Connection btwn matter electricity
• Proved atoms were divisible into smaller
  subatomic particlesBig Shock to Science
  Community
• Discovered electron using Cathode Ray Tube
• Created the Plum Pudding Model Thompsons model
  of the atom resembled a chocolate chip cookie.

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Subatomic Particles

• Millikan
• Oil drop experiment
• Found the charge of one electron
• Electron charge 1.602x10-19 coulombs
• Accepted as -1 charge

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Subatomic Particles

• Ernest Rutherford
• Gold Foil Experiment
• Shoot positive particles at gold foil

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Subatomic Particles

• Ernest Rutherford
• Gold Foil Experiment
• Found that most positive shots went straight
  through but some bounced back
• Atom was largely empty space through which
  electrons moved
• Atoms contained tiny dense region called a
  nucleus that contained most of the mass
• Discovered-nucleus 7 proton.

-An atom the size of two football fields would
have a nucleus the size of a nickel -disproved
Thompsons PPM
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Subatomic Particles

• Chadwick
• Discovered the neutrons
• Neutrons act to separate the protons so that
  they dont repel each other
• Neutrons are like glue to hold the protons
  together

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Atom Smallest particle of an element
that retains the properties of the element