The Structure of Atoms

1
The Structure of Atoms

• Amanda Yu

2
Objectives

• 6(A) Describe the existence and properties of
  subatomic particles
• 4(D) Describe the physical and chemical
  characteristics of an element using the periodic
  table and make inferences about its chemical
  behavior
• 3(E) Research and describe the history of
  chemistry and contributions of scientists

3
What is an Atom?

• Atom
• Smallest particle of an element that retains all
  the properties of that element
• Contains protons, electrons, and neutrons

4
Atom Model Development

• Democritus (Greek philosopher)
• All matter composed of indivisible particles
  called atoms (Greek for uncuttable)
• John Dalton Billiard Ball Model
• Viewed the atom as a small solid sphere
• Joseph Thomson Plumb Pudding Model
• Spherical atom was positive with negative
  particles imbedded throughout

5
Atom Model Development

• Solar System Model
• Ernest Rutherford (top)
• Atom is mostly empty space with a dense
  positively charged nucleus surrounded by negative
  electrons
• Neils Bohr (bottom)
• Electrons travel in circular orbits and that only
  certain orbits were permitted

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Parts of an Atom

• Electron negatively charged, fast-moving
  particle with an extremely small mass
• Proton - positively charged, subatomic particle
  located in the atoms nucleus
• Neutron - subatomic particle located in the
  atoms nucleus, no charge

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Parts of an Atom

• Neutron - subatomic particle located in the
  atoms nucleus, no charge
• Nucleus dense center of an atom that contains
  protons and neutrons
• Model of Nitrogen atom

8
Atomic Number

• Atomic number
• Number of protons in an atom
• Examples
• Hydrogen (H) 1
• Oxygen (O) 8
• Gold (Au) 79
• Mercury (Hg) 80

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Atomic Mass

• Atomic mass
• Weighted average mass of the isotopes of that
  element
• Isotopes
• Atoms of the same element with the same number of
  protons but different numbers of neutrons
• Examples of atomic mass values
• Hydrogen (H) 1.008
• Oxygen (O) 15.999
• Gold (Au) 196.967

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Finding Atomic Information

• How can I find out the number of protons for
  oxygen?
• By using the periodic table
• Atomic number is 8
• Number of protons is 8

Oxygen 8 O 15.999
Element Atomic number Symbol Atomic mass
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Resources

• Content
• Dingrando, L., Gregg, K., Hainen, N., Lampe, P.,
  Roepcke, C., Wistrom, C. (2002).Glencoe
  Chemistry Matter and Change. New York, New
  York The McGraw-Hill Companies, Inc.
• http//www.csmate.colostate.edu/cltw/cohortpages/v
  iney/atomhistory.html (7/25/04)
• http//education.jlab.org/qa/atom_model.html
  (7/24/04)
• Pictures
• http//education.jlab.org/qa/atom_model.html
  (7/24/04) - slides 6 7
• http//particleadventure.org/particleleadventure/f
  rameless/modern_atom/html (7/25/04) - slide 3

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Resources

• Pictures
• http//www.chemheritage.org/EducationalServices/ch
  emach/ans/er.html (7/25/04) - slide 5
• http//www2.physics/umd/edu/redish/Money/bohr.jpg
  (7/25/04) - slide 5
• http//www.csmate.colostate.edu/cltw/cohortpages/v
  iney/atomhistory.html (7/25/04) - slide 4
• Microsoft power point clip art - slide 4
• Amanda Yu - slide 10
• Sounds
• www.wavsource.com/sfx/sfx.htm (7/25/04) - slides
  3, 5, 10
• Microsoft power point sounds slides 11 12