Oxysalts

What are they?  |  How are they named? If we know the formula  | If we know the name  |  Examples  |  IUPAC systematic nomenclatureExercises
   

What are they?

They are ionic compounds that we obtain them by replacing the hydrogen in a oxyacid by metal cations, such as Na+, or non-metallic, as NH4+ (ammonium). When all hydrogens are replaced we will obtain neutral salts, and when some hydrogens are replaced we will obtain acid salts.

How are they named?

Common nomenclature.

It was named following the same rules for oxyacids, but changing suffixes. For the low oxidation numbers the suffix is -ITE, and the high oxidation numbers the suffix is -ATE.

Oxidation numbers Acid Anion

Highest

High

Low

Lowest

per-      -ic

            -ic

            -ous

hypo-    -ous

per-      -ate

            -ate

            -ite

hipo-    -ite

 

If we know the formula

    In the formula:   Na2SO4

a) Separate from the salt cation and anion

Deduces the charge of the anion (negative ion) from the charge of the cation (positive ion)

b) Deduces the oxidation number of the central atom, knowing that the oxygen has oxidation number -2.

c) Recalls oxidation numbers of central element, and writes the prefixes and suffixes.

The first word is the name of the metal, followed immediately by the oxidation number between brackets and in Roman numbers. If the oxidation number of the metal is invariable, it is not indicated. The second word is the name of the anion with the suffixes and prefixes that correspond.

If we know the name

    In the name: Calcium nitrate

a) Write the symbol of the cation with its electrical charge. Based on the prefixes and suffixes deduces the number of oxidation central element involved in the anion:

b) Formulates the oxyacid of N+5

c) Deduces the anion from the acid. The anion has so many negative electrical charges as hydrogens has the acid. Calculate the fewest ions of each type that you need so that the compound be neutral.

 

Examples

 

  Cation Anion Formula
 Calcium bromate Ca+2 BrO3- Ca(BrO3)2
 Sodium hypochlorite Na+ ClO- NaClO
 Aluminum sulfate Al+3 SO4-2 Al2(SO4)3
 Magnesium phosphate Mg+2 PO4-3 Mg3(PO4)2
 Iron(III) nitrate Fe+3 NO3- Fe(NO3)3

 

IUPAC systematic nomenclature

      As in oxyacids we use two nomenclatures: is the additive names and the stoichiometric names.

The additive names for anions: are based on the structure of the anions, naming differently the oxygen that are tied to the acid hydrogens (hydroxido), and the oxygen only united central element (oxido). These names carry prefixes corresponding di-, tri-, tetra- and so on. And are named in alphabetical order followed by the name of the central atom finished in –ate, followed by the charge number, with a minus sign, between brackets. (Ewens-Bassett's system)

The stoichiometric names for anions: are formed by the word "oxido" with the prefix that shows us the number of atoms of oxygen, followed by the central atom finished in –ate, followed by the charge number, with a minus sign, between brackets. (Ewens-Bassett's system)

Anion

Additive names

Stoichiometric names

 CO32-  Trioxidocarbonate(2-)  Trioxidocarbonate(2-)
 NO2-  Dioxidonitrate(1-)  Dioxidonitrate(1-)
 NO3-  Trioxidonitrate(1-)  Trioxidonitrate(1-)
 PO43-  Tetraoxidophosphate(3-)  Tetraoxidophosphate(3-)
 SO32-  Trioxidosulfate(2-)  Trioxidosulfate(2-)
 SO42-  Tetraoxidosulfate(2-)  Tetraoxidosulfate(2-)
 ClO-  Oxidochlorate(1-)  Oxidochlorate(1-)
 ClO2-  Dioxidochlorate(1-)  Dioxidochlorate(1-)
 IO3-  Trioxidoiodate(1-)  Trioxidoiodate(1-)
 IO4-  Tetraoxidoiodate(1-)  Tetraoxidoiodate(1-)
 CrO42-  Tetraoxidochromate(2-)  Tetraoxidochromate(2-)
 Cr2O72-  μ-oxμ-oxidobis(trioxidochromate)(2-)  Heptaoxidodichromate(2-)
 MnO42-  Tetraoxidomanganate(2-)  Tetraoxidomanganate(2-)
 MnO4-  Tetraoxidomanganate(1-)  Tetraoxidomanganate(1-)

       The additive names for salts: Write the name of the cation followed by the name of the anion, with the charge ( Ewens-Bassett's system) in cantions having no fixed oxidation number.

      The stoichiometric names for salts: Write the name of the cation, with the prefixes di-, tri-, tetra-, etc. we suggest repetition of the cation. Following the anion without the charge, if necessary with a prefix, tris, tetrakis, pentakis, hexakis, etc. tell us that the repetition of anion.

Salt

Additive names

Stoichiometric names

 Na2CO3  Sodium trioxidocarbonate(2-)  Disodium trioxidocarbonate
 KNO2  Potassium dioxidonitrate(1-)  Potassium dioxidonitrate
 Ca(NO3)2  Calcium trioxidonitrate(1-)  Calcium bis(trioxidonitrate)
 AlPO4  Aluminum tetraoxidophosphate(3-)  Aluminum tetraoxidophosphate
 Na2SO3  Sodium trioxidosulfate(2-)  Disodium trioxidosulfate
 Fe2(SO4)3  Iron(3+) tetraoxidosulfate(2-)  Diiron tris(tetraoxidosulfate)
 NaClO  Sodium oxidochlorate(1-)  Sodium oxidochlorate
 Ca(ClO2)2  Calcium dioxidochlorate(1-)  Calcium bis(dioxidochlorate)
 Ba(IO3)2  Barium trioxidoiodate(1-)  Barium bis(trioxidoiodate)
 KIO4  Potassium tetraoxidoiodate(1-)  Potassium tetraoxidoiodate
 CuCrO4  Copper(2+) tetraoxidochromate(2-)  Copper tetraoxidochromate
 K2Cr2O7  Potassium μ-oxidobis(trioxidocromate)(2-)  Dipotassium Heptaoxidodicromate
 Na2MnO4  Sodium tetraoxidomanganate(2-)  Disodium tetraoxidomanganate
 Ba(MnO4)2  Barium tetraoxidomanganate(1-)  Barium bis(tetraoxidomanganate)

 

Exercises

In Formulae you have an exercise to write the names of these substances and to check your results. You also have the answer to the exercise.

In Names you have an exercise to write the formulae for these substances and to check your results. You have to introduce the formulae without subscripts, for example for water = H2O. You also have the answer to the exercise.

Formulae 1 Names 1 Formulae 2 Names 2 IUPAC Formulae 1 IUPAC Names1 IUPAC Formulae 2 IUPAC Names2

 


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