SI WORKSHEET 5
1. (All are ions)
Formula
Name
Charge of the ion
NO3
Nitrate
-1
ClO4
Perchlorate
-1
ClO3
Chlorate
-1
NH4
Ammonium
+1
SO4
Sulfate
-2
SO3
Sulfite
-2
PO4
Phosphate
-3
PO3
Phosphite
-3
H3O
Hydronium
+1
OH
hydroxide
-1
2.
Phosphorus trichloride
Sodium nitride
Aluminum phosphate
Acetate
Thiosulfate
Dichromate
Carbonate
Copper (II) Sulfate
PCl3
Na3N
AlPO4
CH3COOS2O32Cr2O72CO32CuSO4
3. Give the Lewis structure and formal charges for Ethanol (C2H5OH)
Formal charge= # of valence electrons – (# of lone pair electrons
+ # of bonds). In this structure the carbons are equal because they both have same # of bonds so:
Carbon= 4 – (0+4)=0 and oxygen= 6 – (4+2)= 0 so this is a neutral molecule. **Extra lone pair on
oxygen does not need to be there
4. Give the Lewis structure, formal charge, and any resonance contributes for sulfate ion.
Which resonance contributor(s) are the most prevalent (stable)
*The Top row shows the MOST correct way to depict the sulfate ion in a Lewis Structure
and its resonance structures. The Bottom row is an acceptable way to draw Sulfate for the
purposes of this class and test. Sulfur is in the 3rd row of periodic table and so it can break
the octet rule. The top row is most correct because the charges on each atom are
minimized. Remember formal charge = val. Electrons – (# of lonepair electrons + #bonds)
Top Row: Sulfur: 6 – (0 + 6) = 0
2-Oxygen (with dub. Bond): 6-(4+2)= 0
2- Single bonded oxygen: 6-(6+1)= -1 *2(
Bottom figure: Sulfur: 6- (0 + 4) =2
This oxygen isn’t present here
4-single bonded O: 6-(6+1)=-1*4
BOTH SUM TO -2 but the charges are minimized in the top row = more stable
5. Give the Lewis structure, formal charge, and any resonance contributes for phosgene
(COCl2). Which resonance contributor(s) is/are the most prevalent (stable)
In Good resonance: C: 4 – ( 0+4)= 0; Oxygen: 6 – (4+2)= 0; 2 Cl: 7 – (6+1)=0
In Bad resonance: C: 4- (0+3)= 1; Oxygen: 6 – (6+1) = -1; 2 Cl: 7 – (6+1)=0
6. Draw the Lewis structure and any resonance structures for Thiocyanate ion (SCN-)
*The bend in the pictures represents a carbon atom. The middle picture with two double
bonds is most stable because the negative charge on the atom resides on the most
electronegative atom