Writing Lewis Structures for Molecular (Covalent) Compounds

1
Writing Lewis Structures for Molecular (Covalent)
Compounds

1. sketch arrangement of atoms (determine central
   atom)
2. determine number of valence e-
3. place two e- in each bond
4. complete octets on non-central atoms
5. place any remaining e- on central atom
6. IF central atom has less than an octet, form
   multiple bonds

2
Drawing Lewis Structures
3
Draw the Lewis structure for the NO21- ion.
First, determine the atomic arrangement.
4
Next, determine the total number of
valence electrons.
5 electrons from the N
6 electrons from each O for 12 more electrons
1 additional electron because it is a monoanion
5
Use the electrons to make electron-pair bonds
between the central and outer atoms.
18 - 4 14 electrons remain
6
Complete the octet of each outer atom.
14 - 12 2 electrons remaining
7
If there are any remaining electrons, put them on
the central atom.
..
All of the valence electrons have now been used.
8
If, and only if, the central atom has fewer than
eight electrons, complete its octet by using
nonbonding electron pairs from outer atoms to
make multiple bonds.
9
In the final Lewis structure, each atom should
have a complete octet of electrons. If it is an
ion, indicate the charge outside of brackets.