Sapling Learning Chapter 1; Problem 2

 

    

The number of Valence e- in the free atom B is 3. In question number 1, there are NO nonbonding e- so you will move on to the bonding e-. 

1) FC=3-0-1/2(6)=0, so therefore the B in BH3 is 0.

In question number 2, there are NO nonbonding e-, so you will move on to the bonding e-. 

2) FC=3-0-1/2(8)= -1, so therefore the B in BH4 is -1 or has a negative formal charge.

In question number 3, there are nonbonding e- and NO bonding e-.

3) FC=7-6-0=1, so therefore the Iodine has a charge of +1 or a positive formal charge.

Only the B in BH4 has a full octet because it has 8 shared electrons.