Question 1

What is an oxidation number?

Accepted Answer

An oxidation number (oxidation state) is a number assigned to an atom representing the hypothetical charge it would have if all bonds were completely ionic. It helps track electron transfer in redox reactions.

Question 2

What are the basic rules for assigning oxidation numbers?

Accepted Answer

Key rules: (1) Free elements have oxidation state 0. (2) Monatomic ions have oxidation state equal to their charge. (3) Oxygen is usually -2 (except in peroxides, -1). (4) Hydrogen is usually +1 (except in metal hydrides, -1). (5) Fluorine is always -1. (6) Sum of oxidation states = overall charge.

Question 3

Why are oxidation numbers important?

Accepted Answer

Oxidation numbers are essential for balancing redox equations, identifying which atoms are oxidized (lose electrons) and reduced (gain electrons), and understanding electron transfer in chemical reactions.

Question 4

Can oxidation numbers be fractions?

Accepted Answer

Yes, in some compounds the average oxidation number per atom can be a fraction. For example, in Fe₃O₄ (magnetite), iron has an average oxidation state of +8/3. This indicates mixed oxidation states among the iron atoms.

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