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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
- The cation is always named first and the anion second.
- A simple cation (obtained from a single atom) takes its name from the name of the element.
- 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.”
- Write the name for the compound by combining the names of the ions.
Examples: Name the compound RbI. F 0 B 7 Rb is the chemical symbol for^ rubidium. F 0 B 7 I is the chemical symbol for iodine, whose root is “iod.” Add the “ide” ending to get^ iodide. F 0 B 7 Put the pieces together to get the name^ rubidium iodide.
Name the compound CaO. F 0 B 7 Ca is the chemical symbol for^ calcium. F 0 B 7 O is the symbol for oxygen, whose root is “ox.” Add the “ide” ending to get^ oxide. F 0 B 7 Put the pieces together to get the name^ calcium oxide.
Name the compound Li3N. F 0 B 7 F 0 Li is the chemical symbol for^ lithium. B 7 N is the chemical symbol for nitrogen, whose root is “nitr.” Add the “ide” ending to get nitride. F 0 B 7 Put the pieces together to get the name^ lithium nitride.
Write the formula for potassium sulfide.
F 0 B 7 The chemical symbol of potassium is^ K. K is in the 1^ st^ column of the periodic table, therefore, its oxidation state is +1. F 0 B 7 Sulfide is derived from sulfur, whose symbol is^ S. Its oxidation state is -2. +1 - F 0 B 7 F 0 So far we have… K S. B 7 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. F 0 B 7 Putting it all together we have^ K^ 2S.
Write the formula for magnesium chloride. F 0 B 7 The chemical symbol of magnesium is^ Mg. Mg is in the 2^ nd^ column of the periodic table, therefore, its oxidation state is +2. F 0 B 7 Chloride is derived from chlorine, whose symbol is^ Cl. Its oxidation state is -1. +2 - F 0 B 7 F 0 So far we have… Mg Cl B 7 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. F 0 B 7 Putting it all together we have^ MgCl^2.
Additional examples NaCl F 0E 0 sodium chloride KI F 0E 0 potassium iodide RbBr F 0E 0rubidium bromide MgS F 0E 0 magnesium sulfide Mg3N^2 F 0E 0 magnesium nitride Sodium fluoride F 0E 0 NaF Strontium oxide F 0E 0 SrO Beryllium chloride F 0E 0 BeCl 2 Cesium sulfide F 0E 0 Ce2S Potassium phophide F 0E 0 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
- The cation is always named first and the anion second.
- 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.
- 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.”
- Write the name for the compound by combining the names of the ions.
F 0 B 7 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. F 0 B 7 Putting it all together we have^ Ni^ 2O^3.
Write the formula for lead (IV) nitride. F 0 B 7 The chemical symbol of lead is^ Pb. The oxidation state is +4. F 0 B 7 Nitride is derived from nitrogen, whose symbol is^ N. Its oxidation state is -3. +4 - F 0 B 7 So far we have Pb N. F 0 B 7 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. F 0 B 7 Putting it all together we have^ Pb^ 3N^4.
Write the name for iron (II) oxide. F 0 B 7 The chemical symbol of iron is^ Fe. The oxidation state is +2. F 0 B 7 Oxide is derived from oxygen, whose symbol is^ O. Its oxidation state is -2. +2 - F 0 B 7 F 0 So far we have Fe^ O B 7 Since the charges already balance there is no additional work to be done. F 0 B 7 Putting it all together we have^ FeO.
Additional examples Fe (^) 2O 3 F 0E 0 Iron (III) oxide CuCl F 0E 0 Copper (I) chloride CuCl 2 F 0E 0 Copper (II) chloride PbS F 0E 0 lead (II) sulfide PbS 2 F 0E 0 lead (IV) sulfide Chromium (VI) oxide F 0E 0 CrO^3 Cobalt (III) sulfide F 0E 0 Co (^) 2S (^3) Nickel (II) bromide F 0E 0 NiBr (^2) Mercury (II) phosphide F 0E 0 Hg (^) 3P 2 Cadmium (II) iodide F 0E 0 CdI (^2)
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
- The first element in the formula is named first, and the full element name is used.
- The second element is named as though it were an anion: root + ide
- Prefixes are used to denote the numbers of atoms present. (See table below)
- 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. F 0 B 7 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. F 0 B 7 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. F 0 B 7 Put the pieces together to get the name^ nitrogen dioxide.
Name the compound N2O. F 0 B 7 N is the chemical symbol of^ nitrogen. Since there are two nitrogen atoms we need to add the prefix di to get dinitrogen. F 0 B 7 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. F 0 B 7 Put the pieces together to get the name^ dinitrogen monoxide.
Write the formula for carbon tetrachloride. F 0 B 7 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. F 0 B 7 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. F 0 B 7 Putting it all together we have^ CCl^4.
Write the formula for dinotrogen pentaoxide. F 0 B 7 F 0 The prefix^ di^ means^^2. Thus there are 2 N atoms in the chemical formula. B 7 The prefix^ penta^ means 5. Thus, there are 5 O atoms in the chemical formula. F 0 B 7 Putting it all together we have^ N^ 2O5.
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
- The cation is always named first and the anion second.
F 0 B 7 F 0 So far we have N O B 7 The LCM of 5 and 2 is 10. Therefore, we need 2 N atoms and 5 O atoms to balance the charges. F 0 B 7 Putting it all together we have^ N^ 2O^5.
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 Na (^) 2SO 4 F 0E 0 sodium sulfate KH2PO 4 F 0E 0 potassium dihydrogen phosphate Fe(NO3) 3 F 0E 0 iron (III) nitrate Mn(OH) 2 F 0E 0manganese (II) hydroxide Na (^) 2SO 3 F 0E 0 sodium sulfite Calcium hydroxide F 0E 0 Ca(OH)^2 Sodium phosphate F 0E 0 Na (^) 3PO 4 Ammonium dichromate F 0E 0 (NH4) (^) 2Cr (^) 2O (^7) Cobalt (II) perchlorate F 0E 0 Co(ClO (^) 4) (^2) Copper (II) nitrite F 0E 0 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!
PO 4 3-^ = phosphate SO 4 2-^ = sulfate NO 3 -^ = nitrate ClO 3 -^ = chlorate CO 3 2-^ = 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 PO 5 3-^ = perphosphate PO 4 3-^ = phosphate (most common) PO 3 3-^ = phosphite PO 2 3-^ = hypophosphite
SO 5 2-^ = persulfate SO 4 2-^ =^ sulfate^ (most common) SO 3 2-^ = sulfite SO 2 2-^ = 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
- Take the name of the anion, add the prefix “ hydro ” and change the ending to “ ic .”
- Add the word “ acid .”
Name the compounds HF. F 0 B 7 We know this is an acid because the chemical formula starts with “H.” F 0 B 7 Take the name of the anion (fluoride) add the prefix “hydro” and change the ending to “ic”: hydrofluoric F 0 B 7 Finally, add the word “acid.” F 0 B 7 hydrofluoric acid
Name the compound HCN. F 0 B 7 We know this is an acid because the chemical formula starts with “H.” F 0 B 7 F 0 There is no oxygen present so we start with the prefix “hydro.” B 7 Next, take the name of the anion (cyanide) and change the ending to “ic”: hydrocyanic F 0 B 7 Finally, add the word “acid.” F 0 B 7 hydrocyanic acid
Write the formula for hydrobromic acid. F 0 B 7 We know the formula starts with^ “H”^ because it is an acid. The charge on hydrogen is +1. F 0 B 7 We also know that the acid does not contain oxygen because of the “hydro” prefix.
- MgO 26. Cu(OH) 2
- ZnBr 2 27. PCl (^5)
- Ca(ClO3) 2 28. LiNO 3
- BaSO 4 29. KH (^) 2PO 4
- AgNO 3 30. CuCN
- H2S 31. KHCO (^3)
- CaO 32. NaHSO (^4)
- H2CO 3 33. Li (^) 2HPO (^4)
- Mg3(PO (^) 4) 2 34. H3PO (^4)
- K2CrO 4 35. MgSO (^4)
- NaI 36. Ca(IO2) (^2)
- Al(NO2) 3 37. SiO (^2)
- ZnSe 38. CuCl
- Sn(MnO (^) 4)^2 39.^ KClO 4
- AsCl 5 40. CaSO 3
- CuSO 3 41. NaBr
- HF 42. P (^) 2O 3
- Fe 2 (SO4) 3 43. HClO
- Sn(Cr2O (^) 7) 2 44. N (^) 2O 4
- AsCl 3 45. NaH
- KCN 46. AlN
- NH4OH 47. PbC (^) 2O (^4)
- Fe(ClO (^) 4) 3 48. H2Se
- HNO 2 49. H3PO (^2)
- CS 2 50. CaH (^2)
Write the formula for each of the following compounds.
- tin (II) nitrate 76. calcium bicarbonate
- zinc (II) phosphate 77. calcium hydroxide
- hypophosphorous acid 78. zinc (II) bisulfate
- iron (III) chloride 79. silver (I) oxide
- lithium sulfide 80. chlorous acid
- silver (I) oxalate 81. lead (IV) oxide
- perchloric acid 82. calcium acetate
- potassium permanganate 83. sodium phosphate
- strontium hypochlorite 84. copper (I) oxide
- copper (I) sulfite 85. phosphorous acid
- carbon (IV) sulfide 86. hydroiodic acid
- calcium oxide 87. sodium fluoride
- barium carbonate 88. phosphorus (V) oxide
- antimony (III) dichromate 89. sulfur (II) bromide
- silicon (IV) oxide 90. aluminum (III) sulfate
- iron (II) carbonate 91. nitrogen (III) oxide
- sodium cyanide 92. aluminum (III) iodide
- carbon (IV) chloride 93. iron (III) phosphate
- cesium fluoride 94. zinc (II) perchlorate
- sodium chromate 95. sodium dihydrogen phosphate
- hydrosulfuric acid 96. sulfurous acid
- aluminum (III) oxide 97. strontium carbonate
- ammonium phosphate 98. copper (II) hydroxide
- boron (III) fluoride 99. iron (II) oxalate
- radium sulfate 100. phosphorous (V) sulfide
Common Polyatomic Ions
Formula Name
NH 4 +^ ammonium
C 2 H 3 O 2 -^ acetate
CO 3 2-^ carbonate
HCO 3 -^ bicarbonate
ClO-^ hypochlorite
ClO 2 -^ chlorite
ClO 3 -^ chlorate
ClO 4 -^ perchlorate
CrO 4 2-^ chromate
Cr 2 O 7 2-^ dichromate
CN-^ cyanide
OH-^ hydroxide
NO 2 -^ nitrite
NO 3 -^ nitrate
MnO 4 -^ permanganate
PO 4 3-^ phosphate
HPO 4 2-^ monohydrogen phosphate
H 2 PO 4 -^ dihydrogen phosphate
SO 3 2-^ sulfite
SO 4 2-^ sulfate
HSO 4 -^ bisulfate
C 2 O 4 2-^ oxalate
O 2 2-^ peroxide
