While there are many thousands of different chemical compounds there is a very definite system of nomenclature whereby we can name or write chemical formulas for most compounds. We divide the compounds into two main types – binary compounds and ternary compounds.

 

Binary Compounds

 

All true binary compounds contain only two elements. The name of every binary compound ends with “ide.” Binary compounds come in three types. They are:

            Type I............. the metal forms only one type of cation

            Type II............ the metal forms two or more types of cations

            Type III.......... contains only nonmetals

We will look at each type, one at a time.

 

Type I Binary Compounds

 

For Type I binary compounds the metal present can be found in either Group 1 or Group 2 on the periodic table. The naming system for this type of compound is quite simple and is found below.

 

Rules for naming Type I binary compounds

1.         The cation is always named first and the anion second.

2.         A simple cation (obtained from a single atom) takes its name from the name of the element.

3.         A simple anion (obtained from a single atom) is named by taking the first part of the element name (the root) and adding the letters “IDE.”

4.         Write the name for the compound by combining the names of the ions.

 

Examples:

Name the compound RbI.

·        Rb is the chemical symbol for rubidium.

·        I is the chemical symbol for iodine, whose root is “iod.” Add the “ide” ending to get iodide.

·        Put the pieces together to get the name rubidium iodide.

 

Name the compound CaO.

·        Ca is the chemical symbol for calcium.

·        O is the symbol for oxygen, whose root is “ox.” Add the “ide” ending to get oxide.

·        Put the pieces together to get the name calcium oxide.

 

Name the compound Li3N.

·        Li is the chemical symbol for lithium.

·        N is the chemical symbol for nitrogen, whose root is “nitr.” Add the “ide” ending to get nitride.

·        Put the pieces together to get the name lithium nitride.

 

Write the formula for potassium sulfide.

·        The chemical symbol of potassium is K. K is in the 1st column of the periodic table, therefore, its oxidation state is +1.

·        Sulfide is derived from sulfur, whose symbol is S. Its oxidation state is -2.

                                               +1 -2

·        So far we have… K S.

·        The total positive charge must balance the total negative charge. Therefore, we need 2 K atoms to give a total positive charge of +2. This balances the -2 charge on the sulfur.

·        Putting it all together we have K2S.

 

Write the formula for magnesium chloride.

·        The chemical symbol of magnesium is Mg. Mg is in the 2nd column of the periodic table, therefore, its oxidation state is +2.

·        Chloride is derived from chlorine, whose symbol is Cl. Its oxidation state is -1.

                                                +2       -1

·        So far we have… Mg  Cl

·        The total positive charge must balance the total negative charge. Therefore, we need 2 chlorine atoms to give a total negative charge of -2. This balances the charge on the magnesium.

·        Putting it all together we have MgCl2.

 

Additional examples

NaCl à sodium chloride

KI à potassium iodide

RbBr à rubidium bromide

MgS à magnesium sulfide

Mg3N2 à magnesium nitride

Sodium fluoride à NaF

Strontium oxide à SrO

Beryllium chloride à BeCl2

Cesium sulfide à Ce2S

Potassium phophide à K3P

 

Type II Binary Compounds

 

For Type II binary compounds the metal present is NOT found in either Group 1 or Group 2 on the periodic table. The naming system for this type of compound is found below.

 

Rules for naming Type II binary compounds

1.         The cation is always named first and the anion second.

2.         A simple cation (obtained from a single atom) takes its name from the name of the element. Include a Roman numeral to indicate the oxidation number (charge) on the metal cation.

3.         A simple anion (obtained from a single atom) is named by taking the first part of the element name (the root) and adding the letters “IDE.”

4.         Write the name for the compound by combining the names of the ions.

 

Roman numerals

1......... I                 6......... VI

2......... II                7......... VII

3......... III              8......... VIII

4......... IV              9......... IX

5......... V               10....... X

 

Name the compound FeCl2.

·        Fe is the chemical symbol for iron.

o       Fe is not in the 1st or 2nd column; therefore a Roman numeral is needed in the name. We’ll come back to that shortly.

·        Cl is the chemical symbol for chlorine, whose root is “chlor.” Add the “ide” ending to get chloride.

·        At this point we have iron (??) chloride.

·        To find the Roman numeral…

o       Find the charge of the anion.

§         Cl has a -1 charge.

o       Multiply times the number of those atoms to get the total negative charge.

§         There are 2 Cl atoms.

§         2 times -1 = -2. <--- total negative charge.

o       Balance total negative charge with total positive charge.

§         The total negative charge of -2 must be balanced with a total positive charge of +2.

o       Divide the total positive charge by the number of atoms to get Roman numeral.

§         There is only 1 Fe

§         +2 divided by 1 = +2. The Roman numeral is II.

·        Put the pieces together to get the name iron (II) chloride.

 

Name the compound PbS2.

·        Pb is the chemical symbol for lead.

o       Pb is not in the 1st or 2nd column; therefore a Roman numeral is needed.

·        S is sulfur, whose root is “sulf.” Add the “ide” ending to get sulfide.

·        At this point we have lead (??) sulfide.

·        To find the Roman numeral…

§         S has a charge of -2.

§         There are 2 sulfur atoms so…. 2 x -2 = -4. <---- total negative charge

§         The total positive charge must be +4.

§         There is 1 lead atom so… +4 ÷ 1 = +4. The Roman numeral is IV.

·        Put the pieces together to get the name lead (IV) sulfide.

 

Write the formula for nickel (III) oxide.

·        The chemical symbol of nickel is Ni. The oxidation state is +3, as given by the Roman numeral.

·        Oxide is derived from oxygen, whose symbol is O. Its oxidation state is -2.

                                           +3   -2

·        So far we have Ni O.

·        In order to balance the charges we find the least common multiple (LCM) of 3 and 2. The LCM is 6. We need two Ni atoms (+6 ÷ +3 = 2) and three O atoms (-6 ÷ -2 = 3) to balance the charges.

·        Putting it all together we have Ni2O3.

 

Write the formula for lead (IV) nitride.

·        The chemical symbol of lead is Pb. The oxidation state is +4.

·        Nitride is derived from nitrogen, whose symbol is N. Its oxidation state is -3.

                                           +4   -3

·        So far we have Pb N.

·        The LCM of 4 and 3 is 12. We need three Pb atoms (+12 ÷ +4 = 3) and 4 N atoms    (-12 ÷ -3 = 4) to balance the charges.

·        Putting it all together we have Pb3N4.

 

Write the name for iron (II) oxide.

·        The chemical symbol of iron is Fe. The oxidation state is +2.

·        Oxide is derived from oxygen, whose symbol is O. Its oxidation state is -2.

                                           +2      -2

·        So far we have Fe   O

·        Since the charges already balance there is no additional work to be done.

·        Putting it all together we have FeO.

 

Additional examples

Fe2O3 à Iron (III) oxide

CuCl à Copper (I) chloride

CuCl2 à Copper (II) chloride

PbS à lead (II) sulfide

PbS2 à lead (IV) sulfide

Chromium (VI) oxide à CrO3

Cobalt (III) sulfide à Co2S3

Nickel (II) bromide à NiBr2

Mercury (II) phosphide à Hg3P2

Cadmium (II) iodide à CdI2

 

Type III Binary Compounds

 

            Type III binary compounds contain no metal atoms. There are two different naming systems for Type III binary compounds: the “old system” and the “new system.” The old system uses prefixes to indicate the number of each atom present and the new system is identical to that used for naming Type II compounds.

 

It is important to note that only one system can be used at a time. NEVER mix prefixes and Roman numerals.

 

Rules for naming Type III binary compounds: the OLD SYSTEM

1.         The first element in the formula is named first, and the full element name is used.

2.         The second element is named as though it were an anion: root + ide

3.         Prefixes are used to denote the numbers of atoms present. (See table below)

4.         The prefix mono- is never used for naming the first element.

 

Prefixes

1......... mono          6......... hexa

2......... di               7......... hepta

3......... tri               8......... octa

4......... tetra           9......... nona

5......... penta          10....... deca

 

Name the compound NO2.

·        N is the chemical symbol of nitrogen. Since there is only one nitrogen atom AND it is the first element the prefix mono is not used.

·        O is the chemical symbol of oxygen, whose root is ox. Add the ide ending to get oxide. There are two oxygen atoms so we also add the prefix di to get dioxide.

·        Put the pieces together to get the name nitrogen dioxide.

 

Name the compound N2O.

·        N is the chemical symbol of nitrogen. Since there are two nitrogen atoms we need to add the prefix di to get dinitrogen.

·        O is the chemical symbol of oxygen, whose root is ox. Add the ide ending to get oxide. There is only one oxygen atom we add the prefix mono (mono IS used for the second element) to get monoxide.

·        Put the pieces together to get the name dinitrogen monoxide.

 

Write the formula for carbon tetrachloride.

·        The chemical symbol of carbon is C. There is no prefix before carbon in the chemical name, therefore, there is only 1 C atom in the chemical formula.

·        Tetrachloride has the prefix tetra which means there are 4 atoms present. Chloride is derived from chlorine, whose symbol is Cl. Thus, there are 4 Cl atoms in the chemical formula.

·        Putting it all together we have CCl4.

 

Write the formula for dinotrogen pentaoxide.

·        The prefix di means 2. Thus there are 2 N atoms in the chemical formula.

·        The prefix penta means 5. Thus, there are 5 O atoms in the chemical formula.

·        Putting it all together we have N2O5.

 

            Now let us apply the “new system” to these same compounds. For Type III binary compounds the “new system” is identical to that used to name Type II binary compounds. The advantage to using the new system is that you have one less system to learn.

 

Rules for naming Type III binary compounds: the NEW SYSTEM

1.         The cation is always named first and the anion second.

2.         A simple cation (obtained from a single atom) takes its name from the name of the element. Include a Roman numeral to indicate the oxidation number (charge) on the metal cation.

3.         A simple anion (obtained from a single atom) is named by taking the first part of the element name (the root) and adding the letters “IDE.”

4.         Write the name for the compound by combining the names of the ions.

 

Name the compound NO2.

·        N is the chemical symbol for nitrogen.

o       Nitrogen is not in the 1st or 2nd column; therefore a Roman numeral is needed in the name.

·        O is the symbol for oxygen, whose root is “ox.” Add the “ide” ending to get oxide.

·        At this point we have nitrogen (??) oxide.

·        To find the Roman numeral…

§         O has a charge of -2.

§         2 oxygen atoms times -2 = -4. <---- total negative charge.

§         The total negative charge of -4 must be balanced with a total positive charge of +4.

§         +4 divided by 1 (one N atom) = +4. The Roman numeral is IV.

·        Put the pieces together to get the name nitrogen (IV) oxide.

 

Name the compound N2O.

·        N is the chemical symbol for nitrogen.

o       Nitrogen is not in the 1st or 2nd column; therefore a Roman numeral is needed in the name.

·        O is the symbol for oxygen, whose root is “ox.” Add the “ide” ending to get oxide.

·        At this point we have nitrogen (??) oxide.

·        To find the Roman numeral….

§         O has a charge of -2.

§         2 oxygen atoms times -2 = -4. <---- total negative charge.

§         The total positive charge must be +2.

§         +2 divided by 2 (2 N atoms) = +1. The Roman numeral is I.

·        Put the pieces together to get the name nitrogen (I) oxide.

 

Write the formula for carbon(IV) chloride.

·        The symbol for carbon is C. The oxidation state is +4, as given by the Roman numeral.

·        Chloride is derived from chlorine. The charge on chlorine is -1.

                               +4   -1

·        So far we have C  Cl

·        The LCM of 4 and 1 is 4. We need 1 C atom (+4 ÷ +4 = 1) and 4 Cl atoms (-4 ÷ -1 = 4) to balance the charges.

·        Putting it all together we have CCl4.

 

Write the formula for nitrogen (V) oxide.

·        The symbol for nitrogen is N. The Roman numeral indicates a charge of +5.

·        Oxide is derived from oxygen. The charge on oxygen is -2.

                                  +5    -2

·        So far we have N  O

·        The LCM of 5 and 2 is 10. Therefore, we need 2 N atoms and 5 O atoms to balance the charges.

·        Putting it all together we have N2O5.

 

Ternary Compounds

(A.K.A. Compounds that contain polyatomic ions)

 

An ion is an atom with an electric charge (positive or negative).

A polyatomic ion is a group of atoms with an electric charge. (Even though it is a group of atoms it acts like it were a single atom.)

 

The names of nearly all polyatomic ions end with the letters –ate or –ite. Beware three exceptions: cyanide, hydroxide, and peroxide. These ions end with “ide” which can trick into thinking you have a binary compound when you actually have a ternary compound.

 

Naming ternary compounds

Follow the naming systems for Type I and Type II binary compounds but…

DON’T CHANGE THE NAME OF THE POLYATOMIC ION.

 

Examples

Na2SO4 à sodium sulfate

KH2PO4 à potassium dihydrogen phosphate

Fe(NO3)3 à iron (III) nitrate

Mn(OH)2 à manganese (II) hydroxide

Na2SO3 à sodium sulfite

Calcium hydroxide à Ca(OH)2

Sodium phosphate à Na3PO4

Ammonium dichromate à (NH4)2Cr2O7

Cobalt (II) perchlorate à Co(ClO4)2

Copper (II) nitrite à Cu(NO2)2

 

Naming Polyatomic Ions that Contain Oxygen

            There are many atoms that form several different polyatomic ions with oxygen. The naming system for these ions is based on two things: the most common ion in each series and the number of oxygen atoms compared to the most common ion. The ones that concern us most are ions of phosphorus, sulfur, nitrogen, chlorine, and carbon. Memorize these ions!

 

            PO43-    = phosphate

            SO42-    = sulfate

            NO3-    = nitrate

            ClO3-    = chlorate

            CO32-   = carbonate

 

Naming Polyatomic Ions that Contain Oxygen

One more oxygen that the most common............... per___ate

Most common..................................................... ___ate

One less oxygen that the most common.................. ___ite

Two less oxygens than the most common............... hypo___ite

 

Examples

            PO53-    = perphosphate

            PO43-    = phosphate (most common)

            PO33-    = phosphite

            PO23-    = hypophosphite

 

            SO52-    = persulfate

            SO42-    = sulfate (most common)

            SO32-    = sulfite

            SO22-    = hyposulfite

 

            Note: Some of the ions do not exist in the real world, they are written here to show how to use the naming system.

 

Naming Acids

            For this class, ALL acids begin with H (hydrogen). The names of ALL acids end with the word “acid.” There are two types of acids: those that contain oxygen and those that do not.

 

Naming acids that DO NOT contain oxygen

1.         Take the name of the anion, add the prefix “hydro” and change the ending to “ic.”

2.         Add the word “acid.”

 

Name the compounds HF.

·        We know this is an acid because the chemical formula starts with “H.”

·        Take the name of the anion (fluoride) add the prefix “hydro” and change the ending to “ic”: hydrofluoric

·        Finally, add the word “acid.”

·        hydrofluoric acid

 

Name the compound HCN.

·        We know this is an acid because the chemical formula starts with “H.”

·        There is no oxygen present so we start with the prefix “hydro.”

·        Next, take the name of the anion (cyanide) and change the ending to “ic”: hydrocyanic

·        Finally, add the word “acid.”

·        hydrocyanic acid

 

Write the formula for hydrobromic acid.

·        We know the formula starts with “H” because it is an acid. The charge on hydrogen is +1.

·        We also know that the acid does not contain oxygen because of the “hydro” prefix.

·        Removing the “hydro” and “ic” leaves us with “brom”, the root of bromine or Br. The charge on bromine is -1.

                                          +1    -1

·        So far we have H  Br

·        Balance the charges to get the formula HBr.

 

Write the formula for hydrosulfuric acid.

·        We know the formula starts with “H” because it is an acid. The charge on hydrogen is +1.

·        We also know that the acid does not contain oxygen because of the “hydro” prefix.

·        Removing the “hydro” and “ic” leaves us with sulfur. The charge on sulfur is -2.

                                          +1   -2

·        So far we have H  S

·        Balance the charges to get the formula H2S.

 

Naming Acids the DO contain oxygen

1.         Find the name of the polyatomic ion.

2.         Change “ate” to “ic” or “ite” to “ous.”

3.         Add the word acid.

 

Name the compound HClO4.

·        You know it’s an acid because it starts with H.

·        ClO4- is the perchlorate ion.

·        Change the “ate” to “ic” and get perchloric.

·        Add the word acid and get perchloric acid.

 

Name the compound H2SO3.

·        You know it’s an acid because it starts with H.

·        SO32- is the sulfite ion.

·        Change the “ite” to “ous” and get sulfous.

·        Add the word acid and get sulfous acid.

o       The name is actually sulfurous acid, but I will count sulfous acid correct because it follows the naming system.

 

Write the formula for phosphorous acid.

·        The word acid tells us the first element is H. The charge on H is +1.

·        We also know it is a ternary acid because the prefix “hydro” (meaning binary acid) is missing.

·        Change “ous” to “ite” to get phophite. The formula for phophite is PO3-3.

·        Putting it together and balancing the charges we get H3PO3.

 

Assignment

 

Name each of the following compounds.

 

1.         MgO                                                                26.       Cu(OH)2

2.         ZnBr2                                                               27.       PCl5

3.         Ca(ClO3)2                                                        28.       LiNO3

4.         BaSO4                                                             29.       KH2PO4

5.         AgNO3                                                            30.       CuCN

6.         H2S                                                                  31.       KHCO3

7.         CaO                                                                 32.       NaHSO4

8.         H2CO3                                                             33.       Li2HPO4

9.         Mg3(PO4)2                                                       34.       H3PO4

10.       K2CrO4                                                            35.       MgSO4

11.       NaI                                                                  36.       Ca(IO2)2

12.       Al(NO2)3                                                          37.       SiO2

13.       ZnSe                                                                38.       CuCl

14.       Sn(MnO4)2                                                       39.       KClO4

15.       AsCl5                                                               40.       CaSO3

16.       CuSO3                                                             41.       NaBr

17.       HF                                                                   42.       P2O3

18.       Fe2 (SO4)3                                                        43.       HClO

19.       Sn(Cr2O7)2                                                       44.       N2O4

20.       AsCl3                                                               45.       NaH

21.       KCN                                                               46.       AlN

22.       NH4OH                                                           47.       PbC2O4

23.       Fe(ClO4)3                                                         48.       H2Se

24.       HNO2                                                              49.       H3PO2

25.       CS2                                                                  50.       CaH2

 

Write the formula for each of the following compounds.

 

51.       tin (II) nitrate                                                    76.       calcium bicarbonate

52.       zinc (II) phosphate                                            77.       calcium hydroxide

53.       hypophosphorous acid                                      78.       zinc (II) bisulfate

54.       iron (III) chloride                                              79.       silver (I) oxide

55.       lithium sulfide                                                    80.       chlorous acid

56.       silver (I) oxalate                                                81.       lead (IV) oxide

57.       perchloric acid                                                  82.       calcium acetate

58.       potassium permanganate                                   83.       sodium phosphate

59.       strontium hypochlorite                                       84.       copper (I) oxide

60.       copper (I) sulfite                                               85.       phosphorous acid

61.       carbon (IV) sulfide                                            86.       hydroiodic acid

62.       calcium oxide                                                    87.       sodium fluoride

63.       barium carbonate                                              88.       phosphorus (V) oxide

64.       antimony (III) dichromate                                  89.       sulfur (II) bromide

65.       silicon (IV) oxide                                              90.       aluminum (III) sulfate

66.       iron (II) carbonate                                            91.       nitrogen (III) oxide

67.       sodium cyanide                                                 92.       aluminum (III) iodide

68.       carbon (IV) chloride                                         93.       iron (III) phosphate

69.       cesium fluoride                                                  94.       zinc (II) perchlorate

70.       sodium chromate                                              95.       sodium dihydrogen phosphate

71.       hydrosulfuric acid                                              96.       sulfurous acid

72.       aluminum (III) oxide                                          97.       strontium carbonate

73.       ammonium phosphate                                       98.       copper (II) hydroxide

74.       boron (III) fluoride                                            99.       iron (II) oxalate

75.       radium sulfate                                                   100.     phosphorous (V) sulfide

 

Common Polyatomic Ions

 

Formula         Name

 

NH4+             ammonium

 

C2H3O2-        acetate

CO32-            carbonate

HCO3-           bicarbonate

ClO-              hypochlorite

ClO2-             chlorite

ClO3-             chlorate

ClO4-             perchlorate

CrO42-           chromate

Cr2O72-          dichromate

CN-               cyanide

OH-               hydroxide

NO2-             nitrite

NO3-             nitrate

MnO4-           permanganate

PO43-             phosphate

HPO42-          monohydrogen phosphate

H2PO4-          dihydrogen phosphate

SO32-             sulfite

SO42-             sulfate

HSO4-           bisulfate

C2O42-           oxalate

O22-               peroxide

 

Common Roots of Elements

 

Element                        Root

 

Arsenic                         arsen

Bromine                       brom

Carbon                         carb

Chlorine                       chlor

Fluorine                        fluor

Hydrogen                     hydr

Iodine                           iod

Nitrogen                       nitr

Oxygen                        ox

Phosphorus                  phosph

Selenium                       selen

Sulfur                           sulf

Tellurium                      tellur