NOTES: Lewis Structures for Ionic Compounds
Review: Lewis Structures of Atoms
Ionic compounds form between _________________ and _____________________.
Write the atomic symbol for each element, 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.
a. On your Lewis structure, cross out (X) the metal’s valence electrons to indicate that they
have been removed.
b. Draw the electrons gained by the nonmetal as X’s to indicate that they came from the metal.
c. Additional metals and nonmetals can be added until all structures are stable (have 8 valence
electrons).
d. 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.
a. 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.
a. List the metal’s atomic symbol first, followed by a subscript indicating the number of atoms
used in your Lewis structure.
b. The list the nonmetal’s atomic symbol, followed by a subscript indicating the number of
atoms used in your Lewis structure.
Lithium Fluoride
Formula: _________________________
Magnesium Bromide
Formula: _________________________
Calcium Oxide
Formula: _________________________
Potassium Nitride
Formula: _________________________
Sodium Sulfide
Formula: _________________________
Aluminum Oxide
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.
a. Show how these unpaired electrons are shared by enclosing one electron from each
atom in an oval.
b. Continue to do this until each unpaired electron is paired up with another unpaired
electron from a different atom.
c. 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.
a. 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
NH3
Cl2O
Step 1/2:
Step 1/2:
Step 1/2:
Step 3/4:
Step 3/4:
Step 3/4:
CH4
CH3Br
IBr
Step 1/2:
Step 1/2:
Step 1/2:
Step 3/4:
Step 3/4:
Step 3/4: