Download Oxidation Numbers (14).

Oxidation Numbers
Oxidation Numbers
• An oxidation number is the charge (or the
apparent charge) of an element in a formula.
+1
-1
NaCl
+1
-2
H2O
0
Fe
+6 -2
SO42-
Oxidation Numbers
1) The sum of the oxidation numbers for each
atom in a formula is ALWAYS equal to the total
charge of the formula!
+1
-1
NaCl
+1
-2
H2O
0
Fe
+6 -2
SO42-
Oxidation Numbers
2) The oxidation number for free elements is
ALWAYS zero (0)!
0
Na
0
Cl2
0
S
3) The oxidation number for monoatomic ions is
ALWAYS equal to the charge of the ion!
+1
Na1+
-1
Cl1-
-2
S2-
Oxidation Numbers
4) When they are bonded to different elements…
a) The oxidation number for group 1 elements
is ALWAYS +1! (except hydrogen)
b) The oxidation number for group 2 elements
is ALWAYS +2!
c) The oxidation number for silver (Ag)
is ALWAYS +1!
d) The oxidation number for zinc (Zn )
is ALWAYS +2!
e) The oxidation number for aluminum (Al)
is ALWAYS +3!
f) The oxidation number for fluorine (F)
is ALWAYS -1!
Na
Ca
Ag
Zn
Al
F
Oxidation Numbers
“The Sweet Sixteen Elements”
Oxidation Numbers
5) The oxidation number for hydrogen is
USUALLY +1.
In hydrides, the oxidation number for
hydrogen is –1.
6) The oxidation number for oxygen is
USUALLY –2.
In peroxides, the oxidation number for
oxygen is –1.
In OF2, the oxidation number for oxygen
is +2.
H
O
Oxidation Numbers
7) The more electronegative element is assigned
the negative oxidation number
8) In BINARY formulas, the oxidation number for:
a) group 17 elements is USUALLY –1.
Cl
b) group 16 elements is USUALLY –2.
S
c) group 15 elements is USUALLY –3.
N
Oxidation Numbers
9) In ALL formulas for compounds and ions,
metals ALWAYS have a positive oxidation
number.
10) In MOST formulas, the first part is assigned a
positive oxidation number and the second part
is assigned a negative oxidation number.
+4 -2
+1 -1
-3 +1
NO2
KBr
NH3
Oxidation Numbers
+2 -1
Ex. (1) CaCl2
+2 -1
Ex. (2) XeF2
+1
Ex. (3) Hg22+
0
Ex. (4) S8
Oxidation Numbers
-1
Ex. (5) F1+1 +1 +4 -2
Ex. (6) KHCO3
0
Ex. (7) Pb
-2
+2 +6 -2
Ex. (8) FeSO4
Oxidation Numbers
+6 -2
Ex. (9) SO3
+6 -2
Ex.(10) MnO42+1
Ex.(11) Cu1+
+1
-1
-3 +1 +5 -2
Ex.(12) NH4NO3
Oxidation Numbers
-1
+2 +5 -2
Ex.(13) Sn(NO3)2
+2 -1
Ex.(14) CaH2
+3 -2
Ex.(15) C2O420
Ex.(16) I2
Oxidation Numbers
+4 -2
Ex.(17) SO32+5 -2
Ex.(18) N2O5
+2
+ -2
Ex.(19) NiS
+5 -1
Ex.(20) PCl5
Oxidation Numbers
+1 -1
Ex.(21) Na2O2
+3 -1
Ex.(22) AlCl3
-3 +1
Ex.(23) NH3
+1 +1 -2
Ex.(24) NaClO
Oxidation Numbers
0
Ex.(25) Ag
-3
+2 +5 -2
Ex.(26) Zn3(PO4)2
+2 -2
Ex.(27) S2O32-1
Ex.(28) O22-
Oxidation Numbers
+1 +5 -2
Ex.(29) KNO3
+1 +6 -2
Ex.(30) Ag2CrO4
+1 -2
Ex.(31) Na2X
+1
-2
Ex.(32) M2O