1. Introduction to Chemical Principles
Chapter 8: Chemical Nomenclature
Gilbert Lewis

2. Nomenclature
Chemical Nomenclature is the system of names used to distinguish compounds from each other and the rules needed to device these names. We will consider how to name:
Binary ionic compounds, which contain a metal and a nonmetal.
Binary molecular compounds, which consist only of nonmetals. (For naming purposes metalloids are treated as nonmetals)
Binary and oxo-acids, compounds that release hydrogen ions when dissolved in water.

3. Classifying Elements & Compounds
Compounds resulting from the combination of a metal and one or nore nonmetal are called ionic
Compounds resulting from the combination of a nonmetal with other nonmetal are considered molecule.
A binary compound is a compound in which only two element are present
A binary ionic compound is an ionic compound in which one element present is a metal and the other element present is a non metal. The metal is always present as the positive ion, and the nonmetal is always present as the negative ion.

4. For nomenclature purposes, there are two types of metal ions:
Fixed Charge metal ions only form one type of positive ion – always has the same charge.
Variable Charge metal ions can form more than one type of positive ion, with the ion type differing in charge and magnitude.

5. Fixed-Charge Metal ions
Fixed-charge metals can form only one type of ion.

6. Variable-Charge Metal Ions
Which metals have a variable charge?
The rest of them!

7. Variable-Charge Metal Ions

8. Naming Binary Ionic Compounds for Metals with Fixed Charge
1. name metal cation first, name nonmetal anion second
2. cation name is the metal name
3. nonmetal anion named by changing the ending on the nonmetal name to -ide

9. Example: Naming Binary Ionic with Fixed Charge Metal CsF
1. Identify cation and anion
Cs = Cs+ because it is Group 1A
F = F− because it is Group 7A
2. Name the cation
Cs+ = cesium
3. Name the anion
F− = fluoride
4. Write the cation name first, then the anion name
cesium fluoride

11. Name the Compound: CaF2
Step 1 From the formula it is a binary compound; only two elements.

13. Naming Binary Ionic Compounds for Metals with Variable Charge
1. name metal cation first, name nonmetal anion second
2. metal cation name is the metal name followed by a Roman numeral in parentheses to indicate its charge
determine charge from anion charge
common ions
3. nonmetal anion named by changing the ending on the nonmetal name to -ide

14. Practice — Find the charge on the cation
1. TiCl4
2. CrO3
3. Fe3N2
4 Cl = 4−,  Ti = 4+
3 O = 6−,  Cr = 6+
2 N = 6−,  3 Fe = 6+, Fe = 2+

15. Example: Naming binary ionic with variable charge metal CuF2
1. Identify cation and anion
F = F− because it is Group 7
Cu = Cu2+ to balance the two (−) charges from 2 F−
2. Name the cation
Cu2+ = copper(II)
3. Name the anion
F− = fluoride
4. Write the cation name first, then the anion name
copper(II) fluoride
Tro: Chemistry: A Molecular Approach, 2/e

16. Example: Writing formula for binary ionic compounds containing variable charge metal manganese(IV) sulfide
1. Write the symbol for the cation and its charge 2. Write the symbol for the anion and its charge 3. Charge (without sign) becomes subscript for other ion 4. Reduce subscripts to smallest whole number ratio 5. Check that the total charge of the cations cancels the total charge of the anions
Mn4+
S2-
Mn4+ S2−
Mn2S4
MnS2
Mn = (1)∙(4+) = +4
S = (2)∙(2−) = −4

17. Practice — What are the formulas for compounds made from the following ions?
copper(II) ion with a nitride ion
iron(III) ion with a bromide ion
Cu3N2
Cu2+ with N3−
Fe3+ with Br−
FeBr3

18. Name the following compounds
1. TiCl4
2. PbBr2
3. Fe2S3
titanium(IV) chloride
lead(II) bromide
iron(III) sulfide

19. Some Common Polyatomic Ions

20. Patterns for Polyatomic Ions
1. Elements in the same column form similar polyatomic ions
same number of O’s and same charge
ClO3− = chlorate \ BrO3− = bromate
2. If the polyatomic ion starts with H, add hydrogen- prefix before name and add 1 to the charge
CO32− = carbonate \ HCO3− = hydrogen carbonate

21. Periodic Pattern of Polyatomic Ions -ate groups

22. Example: Naming ionic compounds containing a polyatomic ion Na2SO4
1. Identify the ions
Na = Na+ because in Group 1A
SO4 = SO42− a polyatomic ion
2. Name the cation
Na+ = sodium, metal with invariant charge
3. Name the anion
SO42− = sulfate
4. Write the name of the cation followed by the name of the anion
sodium sulfate

23. Writing Names of Binary Molecular Compounds of Two Nonmetals
1. Write name of first element in formula
a) element furthest left and down on the Periodic Table
b) use the full name of the element
2. Writes name the second element in the formula with an -ide suffix
a) as if it were an anion, however, remember these compounds do not contain ions!
3. Use a prefix in front of each name to indicate the number of atoms
a) Never use the prefix mono- on the first element

24. Subscript – Prefixes 1 = mono- 2 = di- 3 = tri- 4 = tetra- 5 = penta-
not used on first nonmetal
2 = di-
3 = tri-
4 = tetra-
5 = penta-
6 = hexa-
7 = hepta-
8 = octa-
9 = nona-
10 = deca-
Drop last “a” if name begins with a vowel

25. Example: Naming binary molecular BF3
1. Name the first element
boron
2. Name the second element with an –ide
fluorine  fluoride
3. Add a prefix to each name to indicate the subscript
monoboron, trifluoride
4. Write the first element with prefix, then the second element with prefix
a) drop prefix mono from first element
boron trifluoride

26. Name the Following NO2 PCl5 I2F7 nitrogen dioxide
phosphorus pentachloride
diiodine heptafluoride
Tro: Chemistry: A Molecular Approach, 2/e

27. Example: Binary Molecular dinitrogen pentoxide
Identify the symbols of the elements
nitrogen = N
oxide = oxygen = O
Write the formula using prefix number for subscript
di = 2, penta = 5
N2O5
Tro: Chemistry: A Molecular Approach, 2/e

28. Write Formulas for the Following
dinitrogen tetroxide
sulfur hexafluoride
diarsenic trisulfide
N2O4
SF6
As2S3

29. Common Ions Shown on the Periodic Table

30. An acid is a H-containing molecular compound whose molecules yield hydrogen ions (H+) when dissolved in H2O.
Acids produce H+ in H2O, but an anion is also produced, depending on the structure of the molecular compound. E.g.,
HCl  H+ + Cl-
HNO3  H+ + NO3-
HCN  H+ + CN-

31. Acids
If the anion does not contain oxygen, the acid is named with the prefix hydro– and the suffix –ic.
Examples:
HCl Hydrochloric acid
HCN Hydrocyanic acid
H2S Hydrosulfuric acid

32. Acids If the anion does contain oxygen:
The suffix –ic is added to the root name if the anion name ends in –ate.
Examples:
HNO3 Nitric acid
H2SO4 Sulfuric acid
HC2H3O2 Acetic acid

33. Acids If the anion does contain oxygen:
The suffix –ous is added to the root name if the anion name ends in –ite.
Examples:
HNO2 Nitrous acid
H2SO3 Sulfurous acid
HClO2 Chlorous acid

34. Flowchart for Naming Acids

35. Acid Nomenclature

36. The oxy-ions of chlorine, bromine and iodine all have these trends in common. Look for them below……
perchlorate ClO4-1
chlorate ClO3-1
chlorite ClO2-1
hypochlorite ClO-1
Perbromate BrO4-1
Bromate BrO3-1
Bromite BrO2-1
Hypobromite BrO-1
Periodate IO4-1
Iodate IO3-1
Iodite IO2-1
Hypoiodite IO-1
The most productive method of committing these ions to memory is first memorize the ones that have the “ate” ending. This is the most common ending.

37. Common Student Missteps
For ionic compounds, formulas must be reduced to simplest ratios. Ex: MnO2, not Mn2O4 (Don’t reduce molecular compounds.)
There is a difference between ammonia (NH3) and ammonium ion (NH4+).
Chemical formulas do not show ionic charges. Ex: NaCl, not Na+Cl-
Don’t put parentheses unless they are needed to show more than one of the same ion. Ex: NaNO3, not Na(NO3)

38. Choose the correct formula for the compound
Practice Problem #2
hydrobromic acid
Choose the correct formula for the compound
1. HBrO(aq)
HBr(aq)
3. HBrO3(aq)
4. HBrO2(aq)
5. none of the above