The Structure of an Atom

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The Structure of an Atom
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I. Three Main Parts to the Atom

• Nucleus
• 1) Protons
• a. Positive Charge ()
• b. of Protons Atomic Number
• 2) Neutrons
• a. No charge (neutral)
• b. Neutrons Atomic Mass minus the
  Atomic Number

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• B. Electrons
• 1) Negative Charge (-)
• 2) Electrons Protons
• Atomic
• General Rules about Electrons
• 1. The electrons live in different
  energy levels around the nucleus
• 2. An energy level shell must be filled
  before adding another energy level.

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• a) 1st Energy Level (Closest to the nucleus)
  can only have 2 electrons
• b) 2nd Energy Level Maximum of 8 electrons
• c) 3rd Energy Level
• 1. If the 3rd shell is the outer shell then
  8 electrons maximum.

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• 2. If the 3rd shell is not the outer shell
  then it must have at least 8 electrons but
  not more than 18 electrons.
• 3. 4th Energy Level
• If the 4th shell is the outer shell then 8
  electrons maximum.

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• 3) Valence Electrons The number of electrons
  in the outer energy level. These electrons are
  used in chemical bonds.
• The End