NOTES: Lewis Structures for Ionic Compounds

Review: Lewis Structures of Atoms

Ionic compounds form between ______and ______.

Write the atomic symbol for eachelement, surrounded by a dot for each valence electron. Each side of the symbol (top, bottom, left, right) needs to have one dot before you can start doubling up. Remember there can be up to 8 valence electrons in an atom.

Draw the Lewis Structures for the following atoms:

Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon

Lewis Structures for Ionic Compounds

1.Write the atomic symbol for each element, surrounded by a dot for each valence electron.

2.Transfer electrons from the metal to the nonmetal.

  1. On your Lewis structure, cross out (X) the metal’s valence electrons to indicate that they have been removed.
  2. Draw the electrons gained by the nonmetal as X’s to indicate that they came from the metal.
  3. Additional metals and nonmetals can be added until all structures are stable (have 8 valence electrons).
  4. The number of electrons lost by the metal(s) must equal the number of electrons gained by the nonmetal(s) because electrons cannot be created or destroyed.

3.Draw square brackets around each structure, and write the ion’s charge as a superscript after the brackets.

  1. The overall charge on the compound must equal zero(the amount of positives equals the amount of negatives).

4.Write the formula of the stable compound.

  1. List the metal’s atomic symbol first, followed by a subscript indicating the number of atoms used in your Lewis structure.
  2. The list the nonmetal’s atomic symbol, followed by a subscript indicating the number of atoms used in your Lewis structure.

Lithium Fluoride

/

Calcium Oxide

/ Sodium Sulfide
Formula: ______ /

Formula: ______

/

Formula: ______

Magnesium Bromide /

Potassium Nitride

/ Aluminum Oxide

Formula: ______

/

Formula: ______

/

Formula: ______

NOTES: Lewis Structures for Covalent Compounds

Review: Covalent compounds form between ______and ______.

Lewis Structures for Covalent Compounds

1.Write the atomic symbol for each element, surrounded by a dot for each valence electron.

2.Determine which electrons will be shared. They are the electrons that are not paired up.

  1. Show how these unpaired electrons are shared by enclosing one electron from each atom in an oval.
  2. Continue to do this until each unpaired electron is paired up with another unpaired electron from a different atom.
  3. Each atom (except Hydrogen) needs to follow the octet rule and end up with a total of 8 valence electrons (original and shared).

3.Then rewrite your atoms, replacing the ovals with dashes.

  1. A single dash represents two shared electrons.

4.Re-draw the other electrons that were paired up in your original Lewis structures (from step 1) as dots

HF
Step 1/2: / NH3
Step 1/2: / Cl2O
Step 1/2:
Step 3/4: / Step 3/4: / Step 3/4:
CH4
Step 1/2: / CH3Br
Step 1/2: / IBr
Step 1/2:
Step 3/4: / Step 3/4: / Step 3/4: