1. Chapter 6 Chemical Names and Formulas

2. Section 6.1 Introduction to Chemical Bonding
OBJECTIVES:
Distinguish between ionic and molecular compounds.

3. Section 6.1 Introduction to Chemical Bonding
OBJECTIVES:
Define cation and anion, and relate them to metal and nonmetal.

4. Molecules and Molecular Compounds
About 100 different elements
Millions of compounds from them
Naming is essential in chemistry
Noble gases, such as He and Ne
Isolated atoms- monatomic, they consist of single atoms

5. Molecules and Molecular Compounds
Molecule- smallest electrically neutral unit, still has properties of the substance
Made from only nonmetals
Can be from one element- O2
Can make a compound- CO2

6. Molecules and Molecular Compounds
Properties of molecular compounds
Low melting and boiling points
Usually gas or liquid
Composed of two or more nonmetals
O2, O3, H2O

7. Systematic Naming
There are too many compounds to remember the names of them all.
Compound is made of two or more elements.
Put together atoms.
Name should tell us how many and what type of atoms.

8. Atoms and ions Atoms are electrically neutral.
Same number of protons and electrons.
Ions are atoms, or groups of atoms, with a charge (positive or negative)
Different numbers of protons and electrons.
Only electrons can move.
Gain or lose electrons.

9. F- O2- Anion A negative ion. Has gained electrons.
Nonmetals can gain electrons.
Charge is written as a superscript on the right.
Has gained one electron (-ide is new ending= fluoride) F-
O2-
Gained two electrons (oxide)

10. K+ Ca2+ Cations Positive ions. Formed by losing electrons.
More protons than electrons.
Metals can lose electrons K+
Has lost one electron (no name change for positive ions)
Ca2+
Has lost two electrons

11. Ionic Compounds
Ionic compounds- from joining metal cations and nonmetal anions- they are electrically neutral
Usually solid crystals
Melt at high temperatures

12. Two Types of Compounds Molecular compounds Made of molecules.
Made by joining nonmetal atoms together into molecules.

13. Two Types of Compounds Ionic Compounds Made of cations and anions.
Metals and nonmetals.
The electrons lost by the cation are gained by the anion.
The cation and anions surround each other.
Smallest piece is a FORMULA UNIT.

14. Two Types of Compounds Ionic Molecular Smallest piece Formula Unit
Molecule
Types of elements
Metal and Nonmetal
Nonmetals
Solid, liquid or gas
State
solid
Melting Point
High >300ºC
Low <300ºC

15. Section 6.2 Representing Chemical Compounds
OBJECTIVES:
Distinguish among chemical formulas, molecular formulas, and formula units.

16. Section 6.2 Representing Chemical Compounds
OBJECTIVES:
Use experimental data to show that a compound obeys the law of definite proportions.

17. Chemical Formulas
Shows the kind and number of atoms in the smallest piece of a substance.
Molecular formula- number and kinds of atoms in a molecule.
CO2
C6H12O6

18. Chemical Formulas More than one atom? –use a subscript (H2O)
There are 7 diatomic elements
Hydrogen (H2), Nitrogen (N2), Oxygen (O2), Fluorine (F2), Chlorine (Cl2), Bromine (Br2), and Iodine (I2)
Remember: “Br I N Cl H O F”

19. Ionic Compounds
This formula represents not a molecule, but a formula unit
The smallest whole number ratio of atoms in an ionic compound.
Ions surround each other so you can’t say which is hooked to which. (p. 140)

20. Some Laws:
1. Law of Definite Proportions- in a sample of a chemical compound, the masses of the elements are always in the same proportions.
H2O (water) and H2O2 (hydrogen peroxide)

21. Some Laws:
2. Law of Multiple Proportions- Dalton stated that whenever two elements form more than one compound, the different masses of one element that combine with the same mass of the other element are in the ratio of small whole numbers.
Figure 6.11, p. 141

22. Section 6.3 Ionic Charges OBJECTIVES:
Use the periodic table to determine the charge on an ion.

23. Section 6.3 Ionic Charges OBJECTIVES:
Define a polyatomic ion, and give the names and formulas of the most common polyatomic ions.

24. Charges on ions
For most of the Group A elements, the Periodic Table can tell what kind of ion they will form from their location; monatomic ions
Elements in the same group have similar properties.
Including the charge when they are ions.

25. 1+ 2+ 3+ 3- 2- 1-

26. What about the others?
Groups 4A and 0 do not usually form ions (in fact, Group 0 rarely forms compounds!)
Many transition metals have more than one common ionic charge

27. Naming ions Two methods if more than one charge is possible:
1. Stock system – uses roman numerals in parenthesis to indicate the numerical value
2. Classical method – uses root word with suffixes (-ous, -ic)
Does not give true value

28. Naming ions We will use the Stock system.
Cation- if the charge is always the same (Group A) just write the name of the metal.
Transition metals can have more than one type of charge.
Indicate the charge with roman numerals in parenthesis (Table 6.3, p.144)

29. Name these
Na+
Ca2+
Al3+
Fe3+
Fe2+
Pb2+
Li+

30. Write Formulas for these
Potassium ion
Magnesium ion
Copper (II) ion
Chromium (VI) ion
Barium ion
Mercury (II) ion

31. Naming Anions Anions are always the same charge
Change the element ending to – ide
F- Fluorine

32. Naming Anions Anions are always the same charge
Change the element ending to – ide
F- Fluorin

33. Naming Anions Anions are always the same charge
Change the element ending to – ide
F- Fluori

34. Naming Anions Anions are always the same charge
Change the element ending to – ide
F- Fluor

35. Naming Anions Anions are always the same charge
Change the element ending to – ide
F- Fluori

36. Naming Anions Anions are always the same charge
Change the element ending to – ide
F- Fluorid

37. Naming Anions Anions are always the same charge
Change the element ending to – ide
F- Fluoride

38. Name these
Cl-
N3-
Br-
O2-
Ga3+

39. Write these
Sulfide ion
iodide ion
phosphide ion
Strontium ion

40. Exceptions:
Some of the transition metals have only one ionic charge:
Do not use roman numerals for these:
Silver is always 1+ (Ag+)
Cadmium and Zinc are always 2+ (Cd2+ and Zn2+)
Note Fig. 6.13, p. 145

41. Polyatomic ions Groups of atoms that stay together and have a charge.
Learn these - Table 6.4, p.147
Acetate C2H3O2-
Nitrate NO3-
Nitrite NO2-
Hydroxide OH- and Cyanide CN-
Permanganate MnO4-

42. Polyatomic ions Sulfate SO42- Sulfite SO32- Carbonate CO32-
Chromate CrO42-
Dichromate Cr2O72-
Phosphate PO43-
Phosphite PO33-
Ammonium NH4+

43. Section 6.4 Ionic Compounds
OBJECTIVES:
Apply the rules for naming and writing formulas for binary ionic compounds.

44. Section 6.4 Ionic Compounds
OBJECTIVES:
Apply the rules for naming and writing formulas for ternary ionic compounds.

45. Naming Binary Ionic Compounds
Binary Compounds - 2 elements.
Ionic - a cation and an anion.
To write the names, just name the two ions.
Easy with Representative elements (which are Group A elements)
NaCl = Na+ Cl- = sodium chloride
MgBr2 = Mg2+ Br- = magnesium bromide

46. Naming Binary Ionic Compounds
The problem comes with the transition metals.
Need to figure out their charges.
The compound must be neutral.
same number of + and – charges.
Use the anion to determine the charge on the positive ion.

47. Naming Binary Ionic Compounds
Write the name of CuO
Need the charge of Cu
O is 2-
copper must be 2+
Copper (II) oxide
Name CoCl3
Cl is 1- and there are three of them = 3-
Co must be 3+ Cobalt (III) chloride

48. Naming Binary Ionic Compounds
Write the name of Cu2S.
Since S is 2-, the Cu2 must be 2+, so each one is 1+.
copper (I) sulfide
Fe2O3
Each O is x -2 = -6
2 Fe must = 6+, so each is 3+.
iron (III) oxide

49. Naming Binary Ionic Compounds
Write the names of the following
KCl
Na3N
CrN
Sc3P2
PbO
PbO2
Na2Se

50. Ternary Ionic Compounds
These will have polyatomic ions
At least three elements
name the ions
NaNO3
CaSO4
CuSO3
(NH4)2O

51. Ternary Ionic Compounds
LiCN
Fe(OH)3
(NH4)2CO3
NiPO4

52. Writing Formulas The charges have to add up to zero.
Get charges on pieces.
Cations from name on table.
Anions from table or polyatomic.
Balance the charges by adding subscripts.
Put polyatomics in parenthesis.

53. Writing Formulas Write the formula for calcium chloride.
Calcium is Ca2+
Chloride is Cl-
Ca2+ Cl- would have a 1+ charge.
Need another Cl-
Ca2+ Cl21- (use criss-cross method)

54. Write the formulas for these
Lithium sulfide
tin (II) oxide
tin (IV) oxide
Magnesium fluoride
Copper (II) sulfate
Iron (III) phosphide
gallium nitrate
Iron (III) sulfide

55. Write the formulas for these
Ammonium chloride
ammonium sulfide
barium nitrate

56. Things to look for
If cations have ( ), the number in parenthesis is their charge.
If anions end in -ide they are probably off the periodic table (Monoatomic)
If anion ends in -ate or -ite it is polyatomic

57. Section 6.5 Molecular Compounds and Acids
OBJECTIVES:
Apply the rules for naming and writing formulas for binary molecular compounds.

58. Section 6.5 Molecular Compounds and Acids
OBJECTIVES:
Name and write formulas for common acids.

59. Molecular compounds made of just nonmetals
smallest piece is a molecule
can’t be held together because of opposite charges.
can’t use charges to figure out how many of each atom

60. Molecular are easier!
Ionic compounds use charges to determine how many of each.
Have to figure out charges.
Have to figure out numbers.
Molecular compounds name tells you the number of atoms.
Uses prefixes to tell you the number

61. Prefixes (Table 6.5, p.159) 1 = mono- 2 = di- 3 = tri- 4 = tetra-
5 = penta-
6 = hexa-
7 = hepta-
8 = octa-

62. Prefixes
9 = nona-
10 = deca-
To write the name, write two words:

63. Prefixes Prefix name Prefix name -ide 9 = nona- 10 = deca-
To write the name, write two words:
Prefix
name
Prefix
name
-ide

64. Prefixes Prefix name Prefix name -ide 9 = nona- 10 = deca-
To write the name, write two words:
One exception is we don’t write mono- if there is only one of the first element.
Prefix
name
Prefix
name
-ide

65. Prefixes Prefix name Prefix name -ide 9 = nona- 10 = deca-
To write the name, write two words:
One exception is we don’t write mono- if there is only one of the first element.
No double vowels when writing names (oa oo)
Prefix
name
Prefix
name
-ide

66. Name These
N2O
NO2
Cl2O7
CBr4
CO2
BaCl2

67. Write formulas for these
diphosphorus pentoxide
tetraiodine nonoxide
sulfur hexafluoride
nitrogen trioxide
carbon tetrahydride
phosphorus trifluoride
aluminum chloride

68. Writing names and Formulas
Acids
Writing names and Formulas

69. Acids Compounds that give off hydrogen ions when dissolved in water.
Must have H in them.
will always be some H next to an anion.
The anion determines the name.

70. Naming acids
If the anion attached to hydrogen ends in -ide, put the prefix hydro- and change -ide to -ic acid
HCl - hydrogen ion and chloride ion
hydrochloric acid
H2S hydrogen ion and sulfide ion
hydrosulfuric acid

71. Naming Acids
If the anion has oxygen in it, then it ends in -ate of -ite
change the suffix -ate to -ic acid (use no prefix)
HNO3 Hydrogen and nitrate ions
Nitric acid
change the suffix -ite to -ous acid
HNO2 Hydrogen and nitrite ions
Nitrous acid

72. Name these HF
H3P
H2SO4
H2SO3
HCN
H2CrO4

73. Writing Acid Formulas Hydrogen will always be first
name will tell you the anion
make the charges cancel out.
Starts with hydro?- no oxygen, -ide
no hydro?, -ate comes from -ic, -ite comes from -ous

74. Write formulas for these
hydroiodic acid
acetic acid
carbonic acid
phosphorous acid
hydrobromic acid

75. Section 6.6 Summary of Naming and Formula Writing
OBJECTIVES:
Use the flowchart in Figure 6.21 to write the name of a compound when given its chemical formula.

76. Section 6.6 Summary of Naming and Formula Writing
OBJECTIVES:
Use the flowchart in Figure 6.23 to write a chemical formula when given the name of a compound.

77. Helpful to remember...
1. In an ionic compound, the net ionic charge is zero (criss-cross method)
2. An -ide ending generally indicates a binary compound
3. An -ite or -ate ending means there is a polyatomic ion that has oxygen
4. Prefixes generally mean molecular; they show the number of each atom

78. Helpful to remember...
5. A Roman numeral after the name of a cation shows the ionic charge of the cation
Use the handout sheets provided by your teacher!

79. Summary of Naming and Formula Writing
For naming, follow the flowchart- Fig. 6.21, page 161
For writing formulas, follow the flowchart from Fig. 6.23, p. 162