Choose the true statements regarding the charge-minimized Lewis structure(s) of the BrO2- ion. (selet all that apply)
a. There is only one charge-minimized structure for this ion.
b. There are two charge-minimized resonance structures for this ion.
c. The formal charge on the central Br atom is -1
d. The formal charge on the central Br atom is +1
e. The formal charge on the central Br atom is 0
I think b and e are true ... is this right?
right on!
You are correct. Statements b and e are true regarding the charge-minimized Lewis structure(s) of the BrO2- ion.
To determine the true statements regarding the charge-minimized Lewis structure(s) of the BrO2- ion, we need to consider the valence electrons and the octet rule.
The BrO2- ion consists of a bromine atom (Br) and two oxygen atoms (O).
To begin, let's calculate the total number of valence electrons for the BrO2- ion:
Valence electrons of Br = 7
Valence electrons of O = 6 (2 x 6 = 12)
Charge of the ion = -1
Total valence electrons = Valence electrons of Br + 2 x Valence electrons of O + Charge
= 7 + 2 x 6 + (-1)
= 19
Now, let's construct some possible Lewis structures and analyze the formal charge on the central Br atom.
Structure 1:
In this structure, the bromine atom forms a single bond with one of the oxygen atoms (Br-O), and there is a double bond between the central bromine atom and the other oxygen atom (O-Br=O). This structure is symmetric.
Oxygen atoms are more electronegative than bromine. Therefore, in this structure, we assign both the oxygen atoms a formal charge of -1 and the bromine atom a formal charge of +2.
Formal charge on the central Br atom = Valence electrons of Br - (Number of bonds + Number of lone pair electrons)
= 7 - (1 + 6)
= 0
Structure 2:
In this structure, the bromine atom forms a double bond with one of the oxygen atoms (Br=O), and there is a single bond between the central bromine atom and the other oxygen atom (O-Br-O).
In this structure, we assign the oxygen with a double bond a formal charge of 0, and the other oxygen an atom a formal charge of -1. The bromine atom has a formal charge of -1.
Formal charge on the central Br atom = Valence electrons of Br - (Number of bonds + Number of lone pair electrons)
= 7 - (1 + 6)
= 0
Both of these structures satisfy the octet rule for all atoms and exhibit charge minimization.
Based on the above analysis, the true statements regarding the charge-minimized Lewis structure(s) of the BrO2- ion are:
b. There are two charge-minimized resonance structures for this ion.
e. The formal charge on the central Br atom is 0.
So, your answer is correct.