Atomic Structure

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Chapter 3

• Atomic Structure

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DEMOCRITUS

• Greek philosopher
• 470-380 BC
• Deduced the atom
• Greek for
• Everything in universe is made of

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Lavoisier

• Concluded a chemical reaction

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Proust

• Law of
• A given compound always has the same ratios of
  elements

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Dalton

• Atomic theory of matter

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Daltons Postulates

• Each element is
• All atoms of a given element are

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Daltons Postulates

• Atoms are
• A given compound always

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How did he know?

• Indirect evidence
• Observations on how things reacted

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Scanning Tunneling Microscope

• Atoms in Silicon

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Structure

• Michael Faraday
• Proved atoms contained

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Ben Franklin

• Studied static electricity
• Flew a kite in a thunderstorm
• Dont do this at home
• Concluded 2 charges

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Charges

• Positive ()
• Negative (-)
• Like charges
• Opposite charges
• Built up
• When the electrons jump to a door or person

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Cathode Rays

• TV
• Electrons moving through a glass tube with little
  pressure inside.
• J.J. Thompson

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Atomic Structure Review

• Proton
• Neutron
• Electron

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The Modern Day Atom

• Nucleus
• Orbiting Nucleus

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Atomic Numbers (Z)

• Equal to
• NEVER CHANGES

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Mass Number (A)

• Sum of

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Isotopes of the Elements

• Same
• Different number of

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Isotopes

• Defined
• Will have different mass
• C-12
• C-13

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Average Atomic Mass

• Ave Mass
• No
• No
• Only

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Practice

• What is the average atomic mass of the following
  element.
• Isotope/mass Abundance
• Q-54 43
• Q-55 29
• Q-53 17
• Q-56 11

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Ions of the Elements

• Same number of
• Has lost or gained
• Contains

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Practice

• How many electrons in