Valence Electrons and Lewis Dot diagrams

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Valence Electrons and Lewis Dot diagrams
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Valence Electrons

• Outermost electrons in an atom
• Electrons that interact with other molecules
  during a chemical reaction
• Only the s and p electrons of an atom
• Determined by counting groups (columns) from the
  left of the periodic table to the element of
  interest
• Group 1 1 valence electron
• Group 2 2 valence electrons
• Group 13 3 valence electrons
• Group 14 4 valence electrons
• Group 15 5 valence electrons
• Group 16 6 valence electrons
• Group 17 7 valence electrons
• Group 18 8 valence electrons

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Lewis Dot Structures

• Developed an atomic model using dots to represent
  the valence e- that are involved in bond
  formation
• Remember valence electrons electron present in
  the outermost energy level of an atom
• The symbol is written for the element
• Dots are written around the element illustrating
  how many valence electrons are present

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• H He
• Li Be
• B wait! Remember Hunds rule

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Hunds rule

• Hunds rule requires that p, d, or f orbitals in
  a sublevel must all be filled with one electron
  each before a second electron is allowed to pair
  in any orbital
• B ? N (the three separate p orbitals fill with
  one electron each)
• O ? Ne (the electrons for oxygen, fluorine, and
  neon then form pairs until all of the p orbitals
  are filled

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• Electron dot notation for the representative
  elements.

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Lewis dots are used to show electron movement

• With ions we know they transfer electrons
• Metals (cations) lose electrons
• Called oxidation
• Na ? Na e-
• Nonmetals (anions) gain electrons
• Called reduction
• Cl e- ? Cl -