Oxidation Numbers

What is the oxidation number of free elements? (e.g. Na, C, Cl, Cl₂, P_4, O₂)

• -2

• -1

• 0

• +1

• +2

What is the oxidation number of oxygen when bonded to another element?

• -2

• -1

• 0

• +1

• +2

What is the oxidation number of fluorine when bonded to another element?

• -2

• -1

• 0

• +1

• +2

What is the oxidation number of hydrogen when bonded to another non-metal element?

• -2

• -1

• 0

• +1

• +2

An oxidising agent ​ (a)   in oxidation number as in undergoes ​ (b)   and ​gains electrons.

A reducing agent ​ (c)   in oxidation number as it undergoes ​ (d)   and ​loses electrons.

• decreases
• reduction
• increases
• oxidation

A reducing agent ​increases in oxidation number as it undergoes ​ (a)   ​ and ​​ (b)   electrons.

An oxidising agent ​ decreases in oxidation number as in undergoes ​ (c)   and ​​ (d)   electrons.

• reduction
• oxidation
• loses
• gains

Determine the oxidation numbers in KClO₄.

K: (a)  

Cl:​ (b)  

O: (c)  

• -1
• +1
• -2
• +7
• +5
• 0

Determine the oxidation numbers in C₆H₁₂O₆.

C: (a)  

H:​ (b)  

O: (c)  

• -1
• +1
• -2
• +7
• +5
• 0
• +12
• -12
• +2

Determine the oxidation numbers in Na₂O.

Na - (a)  

O-​ (b)  

• -1
• +1
• -2
• -3
• +3
• 0
• +4
• -4
• +2

Determine the oxidation numbers in CaCl₂.

Ca - (a)  

Cl-​ (b)  

• -1
• +1
• -2
• -3
• +3
• 0
• +4
• -4
• +2