Question

1. Give the oxidation number for each atom in the following elements and ions:

Br₂       Cu²⁺     Ni        O₃        Li⁺        S₈         Ca        F^-       P^3-        H^-        Fe³⁺

Ox #:

2. For ionic compounds made of monoatomic ions, the oxidations numbers are assigned based on the monoatomic rule above. Give the oxidation number for each atom in the following ionic compounds:

Compound	Cation	Cation oxidation number	Anion	Anion oxidation number
NaCl	Na+	+1	Cl-	-1
LiF
CuS

Answer 1

Oxidation number is the charge that an atom carry in a compound or element. Elements have oxidation number of zero and ions have oxidation number equal to their charge.

Br2 : 0

Cu2+ : +2

Ni : 0

O3 : 0

Li+ : +1

S8 : 0

Ca : 0

F- : -1

P3- : -3

H- : -1

Fe3+ : +3

2) LiF :

Cation = Li+ Oxidation number : +1

Anion = F- Oxidation number : -1

CuS :

Cation = Cu2+ . Oxidation number : +2

Anion = S2- Oxidation number : -2