Lewis Structures
Lewis structures keep track of the valence electrons. Valence electrons are most often
described as the highest s and p electrons (beyond the last noble gas core).
1. What is the Lewis structure for a sodium ion?
2. What is the Lewis structure for an oxide ion?
3. What is the Lewis structure for NaBr?
In covalent bonding electrons are shared.
4. Write the electron dot structure for the following:
A) H2
B) Cl2
C) O2
D) N2
Electron dot structures and Lewis structures are about the same. When someone asks for
Lewis structures they usually expect to see a line to represent a single bond.
5. Write the Lewis structure for the following:
A) H2
B) Cl2
C) O2
D) N2
6. What is a free pair of electrons?
7. Write the Lewis structure for H2O and NH3.
8. When allowed to mix these molecules are sometimes said to form NH4OH. Write the
Lewis structure for this ionic compound?
9. What is a coordinate covalent bond?
General rules for writing Lewis structures.
1. Write the skeletal structure.
2. Count the number of valence electrons
3. The central atom (exception B and Be) has to have at least 8 electrons. It can have
more. This can involve double and triple bonds or what is called the expanded
octet.
4. The peripheral electrons have to have 8 unless it is H. It cannot have more.
10. Write the Lewis structure for the following:
A) NF3
B) HNO3
C) CO32D) H2SO4
E) CO2
F) CH2O