A question regarding oxidation numbers

In summary, atoms have a limited number of oxidation numbers they can assume due to energetic reasons. This means that certain oxidation states have significantly lower energy levels compared to others. Chlorine, for example, has an odd number of valence electrons which prevents it from having oxidation numbers of 2 or 4. However, compounds with these oxidation numbers do exist, such as chlorine monoxide and chlorine dioxide. It's important to remember that oxidation numbers are just a tool used in balancing redox reactions and do not reflect any measurable property of the atom.
  • #1
espen180
834
2
How come atoms have only a few oxidation numbers they can assume? For example, Cl can have the oxidation numbers -1, 1, 3, 5, 7. What prevents it from having an oxidation number of say, 2 or 4?
 
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  • #2
Nothing prevents it. It's just energetically unfavorable. That is, the other states have significantly lower energy.

You can really dive in here with how 'deeply' you want to explain it, but to just give the cursory, simplest answer: Chlorine has an odd number of valence electrons (7). If it gained or lost an even number, it'd still have an odd number. The resulting compound would be a radical, which are generally high in energy.
 
  • #3
Who told you chlorine doesn't have compounds with ON 2 and 4?

http://en.wikipedia.org/wiki/Chlorine_monoxide

http://en.wikipedia.org/wiki/Chlorine_dioxide

Just remember that oxidation number is just a number assigned to atoms using some simple rules to help in balancing redox reactions. There is a logic behind, but there is no measurable property of the atom that reflects assigned oxidation numbers.

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  • #4
I get it now. Thanks for the help.
 

1. What are oxidation numbers?

Oxidation numbers are a representation of the number of electrons that an atom has either gained or lost in a chemical reaction. It is used to track the flow of electrons in a reaction and determine the overall charge of an atom or molecule.

2. How are oxidation numbers determined?

Oxidation numbers are determined based on a set of rules. The most common method is to assign oxidation numbers based on the electronegativity of the atoms involved in the reaction. The more electronegative atom is assigned a negative oxidation number, while the less electronegative atom is assigned a positive oxidation number.

3. Why are oxidation numbers important?

Oxidation numbers play a crucial role in determining the type of chemical reaction that is taking place. They also help in balancing equations and predicting the products of a reaction. Additionally, they are used to classify elements as oxidizing agents or reducing agents.

4. Can oxidation numbers change?

Yes, oxidation numbers can change in a chemical reaction. This is because the number of electrons an atom gains or loses may vary depending on the type of reaction and the other atoms involved. In a redox reaction, oxidation numbers of some atoms will increase while those of others will decrease.

5. How do you calculate the oxidation number of a compound?

To calculate the oxidation number of a compound, you need to know the individual oxidation numbers of each element in the compound. Then, you can use the overall charge of the compound to determine the oxidation number of the element with an unknown oxidation number. Alternatively, you can use the sum of individual oxidation numbers to calculate the overall charge of the compound.

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