In naming the compounds one has to first decide whether you are looking at an ionic compound or a molecular compound. We know that metals combined to non-metals will produce compounds that are ionic. Non-metals combined with non-metals will produce compounds that are molecular.

You must be able to identify from the formula given whether you are looking at an ionic or a molecular compound. If the formula has both symbols from non-metals, then the compound would be classified as a molecular compound. Those formulas that have one symbol from a metal combined with symbol from non-metals would make the compound an ionic compound. For example:

Na₂SO₄ would be ionic because it has the sulfate ion which is composed of non-metals combined with Sodium which is a metal. Metals combined with non-metals produce ionic compounds.

PCl₅ would be molecular because Phosphorus and Chlorine are both non-metals and we know that non-metals combined with other non-metals produce molecular compounds.

For your convenience use the following Common Oxidation State of Common Ions Table in order to work the problems on this page.

Try your hand with the following. Identify whether the following compounds are ionic or molecular:

1. CaSO₄
2. CO₂
3. N₂O₄
4. LiCl
5. P₂O₅
6. Cu₃(PO₄)₂

correct answers

Naming compounds involves naming the element that appears first in the formula using the name of the element itself. The second part of the formula which is usually the anion in an ionic compound will end in "ide" for binary ionic compounds. If there is a multi-valent element involved like Iron, Copper, Lead,Tin, or Mercury, one will have to determine which valence is involved before the name can be established. For example, FeCl₃, we know that Fe has two possible valences. We also know that the total positive charge plus the total negative charge will equal zero. We have one Fe and we know that the halogens in binary compounds are -1 so

Let x = valence of one Fe atom

1(x) + 3(-1) = 0

x = +3

so the Fe is in the +3 state so the name is:

Iron (III) Chloride

Let's try another:

What is the name of:

CuS

1. Let x = valence of a Cu atom
2. Recognize that sulfur by itself in an ionic binary compound will be -2
3. 1(x) + 1(-2) = 0

   x - 2 = 0

   x = +2 for Cu

4. Use the name of Copper and place the determined valence as a Roman numeral in parenthesis after the symbol
5. use the name for sulfur but change the last three letters to "ide"
6. the name would be Copper II Sulfide

1. Identify the name of the first symbol: Sodium
2. check to see if it is multi-valent. If not write the name of the element which would be Sodium
3. Identify the element name of the second element, drop the last three letters and add ide so here the element name is Iodine drop the "ine" and add "ide" to get Iodide
4. Place the two names together:

   Sodium Iodide

   Now it is your turn. What is the name of the following:

   1. MgI₂
   2. Hg₂Cl₂
   3. CaO
   4. Cu₃P₂
   5. FeBr₂
   6. K₂O

   When you have decided what the name of each of the above is then check for the correct answers

   Nomenclature of Ternary Ionic Compounds

   Naming Ternary compounds uses the same procedure as Binary Ionic Compounds above. The one big difference is theending of the name. It is seldom ide although in some cases it is. Other more common endings is "ate" and "ite".

   What is the name of Be(HSO₃)₂ ?

   1. Identify the element name of Be which would be Berylium
   2. Identify the HSO₃ which is Hydrogen Sulfite
   3. Add the two together for the name

      Berylium Hydrogen Sulfite

   Here is another. What is the name of Fe(OH)₂
   1. Identify the element name of Fe and recognize that Iron can have more than one valence.
   2. Determine the valence. 1(x) + 2(-1) = 0

      x - 2 = 0

      x = 2

   3. Identify the name of the OH which would be Hydroxide
   4. Add the two together identifying the valence for Fe

      Iron(II) Hydroxide

      Now try your hand with these. Name the following:

      1. PbSO₄
      2. Sn(C₂H₃O₂)₄
      3. Al₂(SO₄)₃
      4. BaCrO₄
      5. K₃PO₄

      When you have given a name for each of the above, check for the correct answers

      Nomenclature of Molecular Compounds

      Molecular Compounds are named differently than ionic compounds. A set of prefixes are used which identify the subscript in the formula. This was discussed in the formula writing lesson.

      Here is an example. Give the name for PCl₃

      Since there is one Phosphorus and three Chlorines we would use the prefix "tri-"

      The name would be :

      Phosphorus Trichloride

      Here is another:

      What is the name for:

      N₂O₄

      Use the prefix Di in front of the elemental name of Nitrogen and use the prefix tetra in front of the oxygen name with droping the ygen and adding the "ide" since it is a binary compound.

      Dinitrogen Tetroxide

      Now let's see if you can do these. What is the name of the following:

      1. SO₂
      2. CCl₄
      3. NO
      4. PCl₅
      5. N₂O₅

      After writing down the names you might want to check correct answers

      Additional information on nomenclature of Inorganic Compounds can be found at nomenclature information sheet (developed by S.E. Van Bramer for chemistry and environmental science courses at Widener University.)

      For further problems involving the naming of compounds try the following nomenclature problem set (problem sets developed by S.E. Van Bramer for chemistry and environmental science courses at Widener University.)

      R. H. Logan, Instructor of Chemistry, Dallas County Community College District, North Lake College.

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      Acknowledgements:

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      Acknowledgements

      Send Comments to R.H. Logan:

      rhl7460@dcccd.edu

      All textual content copyrighted (c) 1997
      R.H. Logan, Instructor of Chemistry, DCCCD
      All Rights reserved
      
      

      Revised: 3/27/97

      What is the name of the following:

      1. MgI₂ = Magnesium Iodide. Magnesium has only one valence. Use the element name for Iodine drop the ine and add the characteristic "ide" ending for binary compounds.

      2. Hg₂Cl₂ = Mercury(I) Chloride.

         Mercury is one of the previously identified multi-valent elements.

         Halogens in any binary compound will be -1 each.

         Let x = valence of a Mercury atom

         2(x) + 2(-1) = 0

         2x - 2 = 0

         2x = 2

         x = +1

         So the mercury is +1 so use the name of mercury placing the valence in parenthesis and use the element name of the second element Chlorine, drop the ine and add the "ide" ending

      3. CaO = Calcium Oxide. Calcium has only one valence so use the element of the first element, use the element name of Oxygen drop the ygen and add ide.

      4. Cu₃P₂ = Copper(II)Phosphide. Copper is multi-valent so determine its valence in this compound. 3(x) + 2(-3) = 0

         3x + (-6) = 0

         3x - 6 = 0

         3x = +6

         x = +2

         Use the element name of Copper placing the II in parenthesis. Use the element for Phosphorus, drop the orus and add ide.

      5. FeBr₂ = Iron (II) Bromide.

         Iron is multi-valent.

         Determine the valence. 1(x) + 2(-1) = 0

         x - 2 = 0

         x = +2

         Use the element name for Iron placing the valence in parenthesis. Use the element name Bromine drop the ine and add ide

      6. K₂O = Potassium Oxide. Potassium has only one valens so use the element name for K which is Potassium. Use the element name for Oxygen drop the ygen and add ide.

      Return to the next section

      Name the following:

      1. PbSO₄ = Lead(II)Sulfate
      2. Sn(C₂H₃O₂)₄ = Tin (IV) Acetate
      3. Al₂(SO₄)₃ = Aluminum Sulfate
      4. BaCrO₄ = Barium Chromate
      5. K₃PO₄ = Potassium Phosphate

      Return to the lesson

      Identify whether the following compounds are ionic or molecular:

      1. CaSO₄ = ionic since Ca is a metal and Sulfate is made of non-metals
      2. CO₂ = molecular since Carbon and Oxygen are non-metals
      3. N₂O₄ = molecular since Nitrogen and Oxygen are non-metals
      4. LiCl = ionic since Li is a metal and Cl is a non-metal
      5. P₂O₅ = molecular since Phosphorus and Oxygen are both non-metals
      6. Cu₃(PO₄)₂ = ionic since Copper is a metal and PO₄ units made of non-metals

      Return to the lesson

      What is the name of the following:

      1. SO₂ = Sulfur Dioxide
      2. CCl₄ = Carbon Tetrachloride
      3. NO = Nitrogen Monoxide
      4. PCl₅ = Phosphorus Pentachloride
      5. N₂O₅ = Dinitrogen Pentoxide

      Return to the end of lesson

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