3.23 (meaning of oxidation)

[Zuri Smith 1A]

Question 3.23 states:
Chlorine can exist in both positive and negative oxidation states. What is the maximum (a) positive and (b) negative oxidation number that chlorine can have?

My question is, what exactly does oxidation mean? Chlorine (Cl) has 7 valence electrons, meaning it needs only one to form an octet. Why is the answer for (a) +7 and for (b) -1?

[Andre-1H]

I believe oxidation state refers to the number of electrons gained or lost. So that seems to line up with the answer you gave, meaning that chlorine at most would lose 7 electrons because it has 7 valence electrons. At most chlorine is going to gain 1 electron. Both of these numbers take the element to the noble gas in that direction. Hope that helped let me know if you need me to clarify anything.

[nikitasridhar_1b]

but since chlorine needs to gain an electron shouldn't its oxidation state be -1

[Andre-1H]

The question says that chlorine can exist in both positive and negative oxidation states. You're probably right in that most chlorine is in an oxidation state of -1.

[Samantha Castro 1D]

In general, the oxidation state is the number of electrons an atom gains, loses, or shares when it forms a chemical bond. The maximum positive oxidation state for chlorine would be +7. While the maximum negative oxidation state for chlorine is -1.

[Zuri Smith 1A]

Ohh okay. So basically +7 means that Cl can give up, at most, 7 negatively charged electrons (which is why it is +7 and not -7). Thank you!

[Jesus A Cuevas - 1E]

Just to clarify for part (d),would we just state that we found the values by adding and subtracting electrons to obtain a full octet, or is other reasoning? Thanks in advance!

[Chem_Mod]

Oxidation state is calculated using the same equation as formal charge except for the bonding electrons. Oxidation state assumes the more electronegative atom claims both bonding electrons instead of half of the bonding electrons.

In HClO₄, the formal charge of Cl is 0, but the oxidation state is +7.
In HCl, the formal charge of Cl is 0, but the oxidation state is -1.