1. Chemical Names and Formulas
Chemistry Chapter 6
Chemical Names and Formulas

2. Section 6.1 Introduction to Chemical Bonding
Objectives:
Distinguish between ionic and molecular compounds
Define cation and anion and relate them to metal and nonmetal

3. Molecules and Molecular Compounds
Monatomic – atoms that exist as isolated atoms. (i.e. most noble gases)
A molecule is the smallest electrically neutral unit of a substance that still has the properties of the substance. Molecules are made up of two or more atoms that act as a unit.

4. Examples of Molecules Ozone (O3) Carbon Dioxide (CO2)
Glucose (C6H12O6)
Water (H2O)

5. Compounds composed of molecules are called molecular compounds.
These compounds tend to have relatively low melting and boiling points.
In most are composed of two or more nonmetals.
Many exist as gases or liquids at room temperature.

6. Ions and Ionic Compounds
Many compounds are composed of particles called ions. Ions are atoms or groups of atoms that have a positive or negative charge.
Ions form when atoms lose or gain electrons.
When an atom loses electrons the charge is positive.
When an atom gains electrons the charge is negative.

7. Cation vs. Anion
A cation is any atom or group of atoms that has a positive charge.
An anion is any atom or group of atoms that has a negative charge.

8. Naming Ions
A positive ion will have the same name as the atomic form of the element with the word ion tagged on the end.
A negative ion will have the same root name as the atomic form of the element with a suffix of –ide and the word ion tagged on the end.

9. Ex #1: Give the name and symbol of the ion formed when:
a selenium atom gains two electrons
Se2- Selenide ion
a gallium atom loses three electrons
Ga3+ Gallium ion
a magnesium atom loses two electrons.
Mg2+ Magnesium ion

10. Ex #2: How many electrons are lost or gained in forming each ion?
Li+
One electron is lost
N3-
Three electrons are gained
Fe2+
Two electrons are lost

11. Compounds composed of cations and anions are called ionic compounds.
Ionic compounds are usually composed of metal cations and nonmetal anions. They are referred to as formula units.
Usually solid crystals at room temperature.
Melt at high temperatures.

12. Characteristics of Molecular and Ionic Compounds
Molecular Compound
Ionic Compound
Representative Unit
Molecule
Formula Unit
(balance of oppositely charged ions)
Type of Element
Nonmetallic
Metallic Combined with Nonmetallic
Physical State
Solid, Liquid, or Gas
Solid
Melting Point
Low
(usually below 300 °C)
High
(usually above 300 °C)

13. Ex #3: Tell whether the following compounds are ionic or molecular.
AlI3 I2
ionic
CaH2
ZnO
Cl2O
CuC2H3O2
molecular

14. Section 6.1 Introduction to Chemical Bonding
Did we meet our Objectives?
Distinguish between ionic and molecular compounds
Define cation and anion and relate them to metal and nonmetal

15. Section 6.2 Representing Chemical Compounds
Objectives:
Distinguish among chemical formulas, molecular formulas, and formula units
Use experimental data to show that a compound obeys the law of definite proportions.

16. Chemical Formulas
A chemical formula shows the kinds and numbers of atoms in the smallest representative unit of the substance.
Some elements chemical formulas must be represented as diatomic:
H2, F2, O2, N2, Cl2, Br2, and I2

17. Molecular Formulas
A molecular formula shows the kinds and numbers of atoms present in a molecule of a compound.
Although a molecular formula shows the composition of a molecule, it tells you nothing about the molecule’s structure.

18. Formula Units
Formula unit – the lowest whole-number ratio of ions in a compound.
This cannot be used to
explain molecular compounds

19. The Law of Definite Proportions
Law of Definite Proportions – regardless of the amount, a compound is always composed of the same elements in the same proportion by mass.
The proportions are found by calculating the percent by mass.

20. Percent by Mass
What is the percent by mass of the elements that make up water? H2O
(mass of hydrogen / mass of water) x 100
(mass of oxygen / mass of water) x 100
(2.02 g / g) x 100 = % Hydrogen
(16.00 g / g) x 100 = % Oxygen

21. Ex #3. Find the percent by mass for each element in the following compounds.
NaCl
CO2

22. Law of Definite Proportion Lab
Nuts & Bolts – In your groups, complete the law of definite proportion task.

23. The Law of Multiple Proportions
Law of Multiple Proportions – The different masses of one element that combine with the same mass of the other element are in the ratio of small whole numbers.

24. Compound B has twice as much lead as Compound A!
Ex #4 Lead forms two compounds with oxygen. One compound contains 2.98 of lead combined with g of oxygen. The other compound contains 9.89 g of lead combined with g of oxygen. What is the lowest whole-number mass ratio of lead in the two compounds that combines with a given mass of oxygen?
Take the mass of lead and divide it by the mass of oxygen for each compound. The ratios should be whole numbers!
Compound A = (2.98 g Pb / g O) = 6.46
Compound B = (9.89 g Pb / g O) = 13.44
B:A = 13.44:6.46 = 2:1
Compound B has twice as much lead as Compound A!

25. Compound A has twice as much carbon as Compound B!
Ex #5. Carbon reacts with oxygen to form two compounds. Compound A contains 2.41 g of carbon for each 3.22 g of oxygen. Compound B contains 6.71 g of carbon for each 17.9 g of oxygen. What is the lowest whole-number mass ratio of carbon that combines with a given mass of oxygen?
Compound A = (2.41 g C / 3.22 g O) = 0.748
Compound B = (6.71 g C / 17.9 g O) = 0.375
A:B = 0.748:0.375 = 2:1
Compound A has twice as much carbon as Compound B!

26. Law of Multiple Proportion Lab
Nuts & Bolts – In your groups, complete the law of multiple proportion task.

27. Section 6.2 Representing Chemical Compounds
Did we accomplish our objectives?
Distinguish among chemical formulas, molecular formulas, and formula units
Use experimental data to show that a compound obeys the law of definite proportions.

28. Section 6.3 Ionic Charges Objectives:
Use the periodic table to determine the charge on an ion
Define a polyatomic ion and give the names and formulas of the most common polyatomic ions

29. Monatomic Ions
Monatomic ions – ions consisting of only one atom. The ionic charge is often determined by using the periodic table.

30. Ionic Charges of Representative Elements
Table 6.2
Ionic Charges of Representative Elements 1A 2A
3A/13
4A/14
5A/15
6A/16
7A/17
0/18
Li+
Be2+
N3-
O2-
F1-
Na+
Mg2+
Al3+
P3-
S2-
Cl1- K+
Ca2+
As3-
Se2-
Br1-
Rb+
Sr2+
I1-
Cs+
Ba2+
Tend
not to
form ions.
Tend
not to
form ions.

31. Naming cations with more than one charge.
There are two methods for naming cations with more than one charge:
Stock System
More common method
Uses Roman numerals to indicate the charge.
Classical System
Older, less preferred method
The root word is used with a suffix of:
ous: lower of the two charges
ic: higher of the two charges

32. Tin (IV) ion Stock System Cu+ Sn4+ Cu2+ Co3+
Name the following cations using the stock system:
Cu+
Sn4+
Copper (I) ion
Tin (IV) ion
Cu2+
Copper (II) ion
Co3+
Cobalt (III) ion

33. Classical System Cu+ Sn4+ Cu2+ Co3+
Name the following cations using the classical system:
Cu+
Sn4+
Cuprous ion
Stannic ion
Cu2+
Co3+
Cupric ion
Cobaltic ion

34. Ferris Wheel

35. Sulfur Argon 2- No ion formed Lead, 4 e- lost Bromine 4+ 1- Strontium
What is the charge of the ion typically formed by each element? (For transition metals with more than one common ionic charge, the number of electrons lost is indicated.)
Sulfur
Argon 2-
No ion formed
Lead, 4 e- lost
Bromine 4+ 1-
Strontium
Copper, 1 e- lost 2+ 1+

36. A few transition metals have only one ionic charge
A few transition metals have only one ionic charge. The names of these cations do NOT have a Roman numeral.
Ag+
Cd2+
Zn2+

37. Polyatomic Ions
Polyatomic ions are tightly bound groups of atoms that behave as a unit and carry a charge.
Most polyatomic ions end in –ite or –ate.
Exceptions include: ammonium, cyanide, and hydroxide.
Table 6.4 lists common polyatomic ions.

38. By examining the relationship among polyatomic ions with an –ite/-ate pair, one can see that the –ate endings have one more oxygen atom than the –ite endings.
NO2- = nitrite
NO3- = nitrate

39. Section 6.3 Ionic Charges Did we meet our objectives?
Use the periodic table to determine the charge on an ion
Define a polyatomic ion and give the names and formulas of the most common polyatomic ions

40. Section 6.4 Ionic Compounds
Objectives:
Apply the rules for naming and writing formulas for binary ionic compounds.
Apply the rules for naming and writing formulas for ternary ionic compounds.

41. Writing Formulas for Binary Ionic Compounds
Compounds composed of two elements are called binary compounds. Binary compounds can be either ionic or molecular.

42. Binary Ionic Compounds
Compounds composed of two different elements, a cation and an anion.
The total number of positive and negative charges must equal.
The cation comes first, then the anion.
Use subscripts to determine the number of atoms of each element.

43. Make a binary ionic compound containing aluminum and sulfur.
Al3+ S2- Both charges must equal zero. Since 3+ and 2- do not equal zero, we need to add additional atoms of each.
Al3+ S2-
S2-
Al2S3

44. Write formulas for these binary ionic compounds.
Copper (II) sulfide
CuS
Potassium nitride
K3N
Sodium iodide
NaI
Calcium chloride
CaCl2

45. Write formulas for compounds formed from these pairs of ions.
Ba2+, S2-
BaS
Li+, O2-
Li2O
Ca2+, N3-
Ca3N2
Cu2+, I-
CuI2

46. Naming Binary Ionic Compounds
Nomenclature is a naming system.
The cation is named first (Roman numerals are needed if there is more than one charge), then the anion is named second (remember the anion will have a suffix of –ide).
Al2O3 aluminum oxide
ZnCl2 zinc chloride
Ca3P2 calcium phosphide

47. Name the following binary ionic compounds.
CoI2
Cobalt (II) iodide
Cs2O
Cesium oxide
ZnS
Zinc sulfide
FeO
Iron (II) oxide

48. Ternary Ionic Compounds
Ternary Ionic Compound – a compound that contains atoms of three different elements.
Ternary ionic compounds usually contain a polyatomic ion.

49. Rules for making an ionic compound with a polyatomic ion.
1. Write the symbols for the ions side by side with the cation first.
Ca2+ NO3-
2. Cross over the charges to give subscripts. Add parentheses around the polyatomic ion if there is more than one.
Ca(NO3)2

50. Write formulas for these ternary ionic compounds.
Potassium sulfate
K2SO4
Magnesium hydroxide
Mg(OH)2
Calcium phosphate
Ca3(PO4)2
Potassium carbonate
K2CO3

51. Naming Ternary Ionic Compounds
When naming ternary ionic compounds from their formulas, you must first recognize the polyatomic ion.
If there are three (or more) different elements in the compound, then you must use the polyatomic ion chart!

52. Name the following compounds.
LiCN
Lithium cyanide
Sr(H2PO4)2
Strontium dihydrogen phosphate
(NH4)2CO3
Ammonium carbonate
Fe(ClO3)3
Iron (III) chlorate

53. Section 6.4 Ionic Compounds
Did we meet our objectives?
Apply the rules for naming and writing formulas for binary ionic compounds.
Apply the rules for naming and writing formulas for ternary ionic compounds.

54. Section 6.5 Molecular Compounds and Acids
Objectives:
Apply the rules for naming and writing formulas for binary molecular compounds
Name and write formulas for common acids.

55. Binary Molecular Compounds
Molecular Compounds have two or more nonmetals.
Prefixes are used to determine the number of atoms.
The suffix of -ide is placed on the second element.
No prefix is used on the first element if there is only one atom.

56. Prefixes Used in Naming Binary Molecular Compounds
Mono-
Hexa-
Di-
Hepta-
Tri-
Octa-
Tetra-
Nona-
Penta-
Deca-

57. Name these binary molecular compounds.
N2O
Dinitrogen monoxide
PCl3
Phosphorous trichloride
SF6
Sulfur hexafluoride
OF2
Oxygen difluoride

58. Write formulas for the following binary molecular compounds.
Nitrogen trifluoride
NF3
Disulfur dichloride
S2Cl2
Dinitrogen tetroxide
N2O4
Dichlorine octoxide
Cl2O8

59. Binary Acids Acids which begin with H and one other element. HCl HBr
Prefix of hydro- plus the root
Suffix of -ic acid
HCl
hydrochloric acid
HBr
hydrobromic acid

60. Oxyacids H2SO4 sulfuric acid
Oxyacids are acids with H and a polyatomic ion.
No prefix
Suffix depends on polyatomic ion
-ate becomes -ic
-ite becomes –ous
H2SO4
sulfuric acid

61. Name the following acids.HF
Hydrofluoric acid
H2CO3
Carbonic acid
H3N
Hydronitric acid
HNO2
Nitrous acid

62. Write formulas for the following acids.
Phosphoric acid
H3PO4
Hydrophosphoric acid
H3P
Phosphorous acid
H3PO3
Nitric acid
HNO3

63. Section 6.5 Molecular Compounds and Acids
Did We Meet Our Objectives?
Apply the rules for naming and writing formulas for binary molecular compounds
Name and write formulas for common acids.