# Naming compounds

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Does this do a good job of naming the compound and explaining how I determined it?

Step 1
Cation: Fe+3
Anion: O-2

Step 2
Iron has two oxidation numbers Fe+2 and Fe+3
The element iron (a transition metal) has an electron configuration of [Ar] 3d6 4s2 with atomic number 26. It has two electrons in its 4s orbital and 6 electrons in its 4d orbital. When iron loses the two 4s electrons, it attains a valency of +2. It can lose one of the paired electrons from the 3d subshell (which provides a more stable configuration), and it attains a valency of +3.

Step 3
Fe2O3 = iron(III) oxide

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There doesn’t seem to be any reason to include the electronic configuration in your answer or to go through how iron can exist as iron(II) or iron(III). You simply need to determine the oxidation state from the molecular formula you are given. The reason the have that second step in the flow chart is because some elements like iron can have multiple oxidation states, which means that unlike elements like oxygen or hydrogen, you can’t immediately tell what it is without doing a little math first. It’s not asking you to explain how an element can get those states based on its configuration or even where the electrons go / come from, which is what you have done.

What I would include is the math for how you determined that the iron in Fe2O3 is iron(III). You’ve written that it has a 3+ oxidation but not how you got to that point.

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The formula represents one molecule of ferric oxide, consisting of 2 atoms of iron and 3 atoms of oxygen.

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No, I mean the math on how you got to +3. Why couldn’t it be +2?

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The iron ion Fe3+, for example, has an oxidation number of +3 because it can acquire three electrons to form a chemical bond, while the oxygen ion O2 has an oxidation number of −2 because it can donate two electrons.

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Still not really what I’m getting at. That doesn’t explain why, based on the molecular formula, you have Fe3+ and not 2+. How did you determine that?

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two Fe atoms have an oxidation state of +3? I’m not sure how else to explain it?

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10 minutes ago, Rachel Maddiee said:

two Fe atoms have an oxidation state of +3? I’m not sure how else to explain it?

Why is it not 2+?

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Can you please give me a hint to what kind of explanation it should be?

are you referring to electron configuration?

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22 minutes ago, Rachel Maddiee said:

Can you please give me a hint to what kind of explanation it should be?

Looking back on your question and the flow chart, I think I might be getting you to explain a more complex concept that you don't need to worry about in this instance. Your explanation in your OP is fine based purely on that. Have you been learning how to assign oxidation states?

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Yes, this is part of my studies. I’m following the example in my book but I need to show my work along with it so I was having trouble with that. I wasn’t sure if my explanation was correct.

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29 minutes ago, Rachel Maddiee said:

Yes, this is part of my studies. I’m following the example in my book but I need to show my work along with it so I was having trouble with that. I wasn’t sure if my explanation was correct.

Okay. It's not totally clear to me if you also need to show how you worked out that the oxidation state of the iron was 3+ or if you can just take that as given. Most naming questions that I see will tell you the oxidation states if it's ambiguous. Since it's not explicitly stated here, maybe you do need to give working for that part as well. Regardless, this part in your original answer:

10 hours ago, Rachel Maddiee said:

The element iron (a transition metal) has an electron configuration of [Ar] 3d6 4s2 with atomic number 26. It has two electrons in its 4s orbital and 6 electrons in its 4d orbital. When iron loses the two 4s electrons, it attains a valency of +2. It can lose one of the paired electrons from the 3d subshell (which provides a more stable configuration), and it attains a valency of +3.

Is not really needed / relevant.

If you do need to show how you figured out that it is Fe3+ and not Fe2+, how would you do that? You've said that it is Fe3+, which is right, but I'm not clear on exactly how you worked that out or if you just guessed / looked it up. Could you elaborate on this part? I can go through it if you don't know how.

I should also ask how you have been shown to determine / calculate oxidation states of atoms in a compound.

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I looked this up. I’m suppose to explain how I determined that is the correct name but I was struggling trying to come up with an explanation.

Ferrous = iron(II)
Ferric = iron(III)

Here is the example in my book.

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Ferrous = iron(II)
Ferric = iron(III)

But you weren't told if it was ferrous or ferric, just given the molecular formula. That is why I am not sure how you are expected to know that it is iron(III) without actually calculating it. Anyway, it doesn't seem to matter. Based on their solution, what you have written is fine, but I would get rid of all the electronic configuration stuff.

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So how should I write it then?

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How you wrote it is fine, but as I said, I would remove some of the stuff about electronic configuration as I don't think it's needed. I have crossed out what you don't need below. You might just add a sentence saying that the iron in Fe2O3 is Fe3+

12 hours ago, Rachel Maddiee said:

Does this do a good job of naming the compound and explaining how I determined it?

Step 1
Cation: Fe+3
Anion: O-2

Step 2
Iron has two oxidation numbers Fe+2 and Fe+3
The element iron (a transition metal) has an electron configuration of [Ar] 3d6 4s2 with atomic number 26. It has two electrons in its 4s orbital and 6 electrons in its 4d orbital. When iron loses the two 4s electrons, it attains a valency of +2. It can lose one of the paired electrons from the 3d subshell (which provides a more stable configuration), and it attains a valency of +3.

Step 3
Fe2O3 = iron(III) oxide

Also, this is a side note, but I believe iron can also have a 6+ oxidation state.

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I’m suppose to give how I determined the name though..

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Okay, but the stuff about electronic configuration doesn’t really do that. If you don’t have to go through the process of determining oxidation state, then it seems to be enough (based on the screen shot you sent of the ref page) to simply say that iron has several oxidation states, but exists as Fe3+ in Fe2O3.

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Okay got it, but is there a better way that I can show how the name is determined?

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Yes, you could go through the process of calculating the oxidation state to show conclusively that it is Fe3+.

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I don’t really know how to do the calculations (for showing my work.)

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Transition metals
Fe2+ has the lower state than oxygen (Fe3+ has the higher state), so “Fe” becomes ferrous. The name of Fe2+O can also be written as ferrous oxide.
The terms “ferric” and “ferrous” are both use to refer to ions containing iron, since iron’s symbol is “Fe.”
Ferrous = iron(II)
Ferric = iron(III)
Oxide = O-2 Anions always take the –ide suffix.

Can i leave this?

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To answer your previous question, I thought I had posted a link for you last night but I guess it didn't post. Have a look through this https://www.chemguide.co.uk/inorganic/redox/oxidnstates.html

I would highly recommend chemguide as a resource for all of your future questions before posting here. They are very thorough.

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How would I show the rules that were applied for naming cations and anions that helped me to determine the name?

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1 hour ago, Rachel Maddiee said:

How would I show the rules that were applied for naming cations and anions that helped me to determine the name?

The point of determining the oxidation state is really just so you can determine what number to put in brackets. In your case, so you know that it is iron(III) oxide and not iron(II) oxide. You've already shown how you got to the oxide part.

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