Properties of Atoms and the Periodic Table

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CHAPTER 18

• Properties of Atoms and the Periodic Table

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Section 1 Structure of the Atom

• Elements are abbreviated in scientific shorthand
• Atom smallest piece of matter
• 1. protons positive charge (p)
• 2. neutrons no charge (n)
• 3. electrons negative charge (e-)

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• Protons and neutrons are made up of smaller
  particles called quarks
• 1. six quarks exist sixth called top quark
• Scientists use models to represent atoms
• 1. electron cloud model

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Section 2 Masses of Atoms

• Atomic mass composed of protons and neutrons
• 1. unit amu
• 2. atomic - protons in an atom

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• B. Isotopes atoms of the same element with
  different numbers of neutrons

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Section 3 The Periodic Table

• Elements organized by increasing atomic
• Groups vertical columns
• 1. elements in same group have the same number
  of electrons in their outer energy level (el)
• 2. each el can have a maximum number of
  electrons
• 3. electron dot diagrams use element symbol
  and dots to represent outer el electrons

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• Periods horizontal rows of elements
• 1. elements classified as metals, nonmetals, or
  metalloids
• 2. elements are synthesized in laboratories all
  over the world

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The Periodic Table