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Naming ionic compounds

  • #1

Homework Statement:

I need help with a question

Relevant Equations:

N/A
8477E823-2FB2-4CCF-A9A6-4CDCBAC047D3.png

Name: Iron (III) oxide
C: Fe+3
A: O-2
My work**
Should this be separated just like this for the first step?
 

Answers and Replies

  • #2
chemisttree
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What do you think? What if you did? What if you didn’t?
 
  • #3
What do you think? What if you did? What if you didn’t?
Yes, I think that answers the first step.
 
  • #4
chemisttree
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If that’s the first step, what is the second step?
 
  • #5
The cation Fe+3 has an oxidation number of +3.
Am I suppose to write it like that?
 
  • #6
chemisttree
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How did you determine that iron was the cation in the first place? How did you determine an oxidation number of +3?
 
  • #7
chemisttree
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If that is the first step, what is the second step?
 
  • #8
Isn’t that the second step?
 
  • #9
chemisttree
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You tell me.
 
  • #10
You tell me.
The oxidation number is the second step but I’m not sure how it should be written.
 
  • #11
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I have made this for my CHEM101 course.
Code:
Type 1 Ionic compounds :
    Non transition metal cation + Non metal anion.
    Name of cation + Name of anion in "ide" form.

Type 2 Ionic compounds :
    Transition metal cation + Non metal anion.
    * Name of cation + ("its charge in roman numerals") + Name of anion in "ide" form.

Ionic compounds with polyatomic ions :
    * Same as above, just replace the name of the anion in "ide" form with the name of the polyatomic ion.

Molecular compounds :
    Both non metal, share a pair of electrons.
    * Prefix + Name of the first element + Prefix + Name of the second element in "ide" form.

! All of the acids' formulae start with Hydrogen.
Binary acids :
    Compounds in which Hydrogen is combined with a non-metal anion.
    "Hydro" + Base name of the non-metal + "ic" + "acid".

Oxyacids :
    Acids made from Hydrogen, Oxygen and at least another element.
    Hydrogen + polyatomic anion containing Oxygen.
    * If the oxoanion's name ends with "ate" :
    Base name of the oxoanion + "ic" + "acid".
    * If the oxoanion's name ends with "ite" :
    Base name of the oxoanion + "ous" + "acid".

Hydrates :
    Compounds that have a specific number of water molecules attached to them.
    Name of the compound + Prefix + "hydrate".
    If water is removed : "Anhydrous" + Name of the compound.
 
  • #12
epenguin
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That list is not complete. Different ions or different oxidation states of the same element have slightly different names.
Try get fixed in mind quickly. Nomenclature is essent in chemistry, but needs to become second nature as pretty boring as a subject in itself.
 
  • #13
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That list is not complete. Different ions or different oxidation states of the same element have slightly different names.
Try get fixed in mind quickly. Nomenclature is essent in chemistry, but needs to become second nature as pretty boring as a subject in itself.
It fitted my needs, it was a one semester course as a non chemistry student, like a general requirement.
 
  • #14
chemisttree
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The oxidation number is the second step but I’m not sure how it should be written.
Great. So tell me how you determined that iron was the cation and oxygen was the anion. After that you can explain how you arrived at the oxidation states you indicated.
This is what the question refers to as, “Using the problem-solving strategy” and explaining your answer in a series of steps.
 
  • #15
phinds
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This is what the question refers to as, “Using the problem-solving strategy” and explaining your answer in a series of steps.
Which is exactly what you need to learn how to do rather than asking us to do it for you.
 
  • #16
Great. So tell me how you determined that iron was the cation and oxygen was the anion. After that you can explain how you arrived at the oxidation states you indicated.
This is what the question refers to as, “Using the problem-solving strategy” and explaining your answer in a series of steps.
The ion Fe3+, for example, has an oxidation number of +3 because it canacquire three electrons to form a chemical bond, while the oxygen ion O2− has an oxidation number of −2 because it can donate two electrons.
 
  • #17
chemisttree
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Good answer, but you haven’t really told us how you arrived at the +3 oxidation state for iron or how you arrived at the oxidation state of -2 for oxygen. You somehow determined those and described the logical implications. Yes, it is true that a +3 oxidation state is capable of forming chemical bonds by accepting 3 electrons but iron also has a known oxidation # +2. Why didn’t you choose +2 for iron? Why didn’t you choose -1 for oxygen?
 
  • #18
Ground state: [Ar] 4s2 3d6
+2 ion: [Ar] 3d6
+3 ion: [Ar] 3d5
Iron can have multiple oxidation states.
 
  • #19
chemisttree
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Hmmm, so you chose iron +3 because [Ar] 3d5? Very insightful!
 
  • #20
I have to write it out like this example.
1D235D4F-CA2D-489D-935C-8435DB707EB7.png
 
  • #21
Step 1
Cation: Fe+3
Anion: O-2
Step 2
Iron has several oxidation numbers.
Step 3
Fe3O2 = iron(III) oxide
 
  • #22
epenguin
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I don't think it is useful to develop a Socratic dialogue to try make you answer what I was asking in #12.
You have or certainly will come across the -ous, -ic suffixes
As in Ferrous ion/oxide/chloride for Fe2+, FeO, FeCl2
Ferric ion/oxide/chloride for Fe3+, Fe2O3, FeCl3

Or Cuprous ion/oxide/chloride Cu+, Cu2O, CuCl
Cupric ion/oxide/chloride Cu2+, CuO, CuCl2

and then Stannous Sn2+, SnO, SnCl2, Stannic Sn+4, SnO2, SnCl4

With Mercurous/ic those are the main ones for metals/cations you are likely to hear, but I have certainly heard of cobaltous/cobaltic, and even Titanous/Titanic! Then for nonmetallic anions there are sulphurous/ic, phosphorous/ic, bromous/ic etc.

So the rule as in these examples is that when an element has two common oxidation states other than 0, the substance with the lower number (positive or negative) is called -ous, and the higher one -ic. Above we had examples where the where the -ous had oxidation levels +1, +2, +3 and the -ic 1 or 2 above, +2, +3, +4.

This terminology begins to sound a little old-fashioned and I think it's become more common to indicate oxidation state by formula with number, eg Cu(1), Cu(2) even in speaking; Roman numerals I,II, III are also used. Or indicated another way, e.g. titanium dioxide, lead dioxide. I don't know if there have been any official rulings about all this, but you certainly will still encounter the -ous, -ic terminology – it suffices to look at the chemical catalogues.

https://www.sccollege.edu/Departments/STEM/Documents/Handouts/GenChem_Nomenclature_Updated.pdf
http://www.chm.bris.ac.uk/motm/ferric-chloride/ferric-chlorideh.htm
 
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