1. Naming & Calculating Chemical Compounds
Unit3 – Lecture 2

2. Recap – Bonding Occurs…
…to fill the outer level of electrons of elements
you can predict bonding by observing trends on the periodic table:
type of element: metals, non metals, etc
valence electrons: for lewis diagrams
oxidation #: criss-cross method

3. Counting Atoms
A Chemical Formula shows how many of which atoms are in a molecule
A Subscript is a number placed below and behind a symbol to show how many of which atoms are present
H2O

4. Counting Atoms
A Coefficient is placed in front of a molecule to show more than one molecule
3H2O

5. H2 N2 O2 F2 I2 Cl2 Br2 Counting Atoms
A Diatomic Molecule shows two atoms of the same nonmetal (usually in gas form) that have bonded together
Reactive nonmetals will bond with one another if no other substance is available for bonding

6. Ca(OH)2 NH4Cl Polyatomic Ions A group of atoms that behave as one atom
Keep together as a unit
Listed on p. 619
If more than one polyatomic ion is present in a molecule, parentheses set it apart
Still use a subscript to show how many
Ca(OH)2
NH4Cl

7. Oxidation Numbers
A positive or negative sign used to show what type of ion is formed after an atom has gained or lost enough electrons to be chemically stable
Written like a charge sign (upper right)
Always included with a list of polyatomic ions

8. BASE OXIDATION NUMBERS BY GROUP ±
USE ROMAN NUMERALS

9. Oxidation #s – cont’d
Transition metals have more than one oxidation number!!!!
Fe[III] = Fe+3 = Iron with +3 oxidation number
Fe[II] = Fe+2 = Iron with +2 oxidation number
Mn[II] = Mn+2 = Manganese with +2 oxidation number
Mn[III] = Mn+3 = Manganese with +3 oxidation number

10. Making Formulae – the “Criss-Cross” Method
cation first – write element & oxidation #
anion next – write element & oxidation #
without the + or – sign
write the oxidation # from one symbol on the other as a subscript
remember to add parentheses around polyatomic ions
don’t write the #1, it is implied
reduce any evenly-divisible subscripts

11. Practice What is the correct formula for a bond between…
Carbon and Hydrogen?
CH C2H2 CH3
C2H3 CH4
Sodium and Nitrogen?
NaN Na2N2 Na3N
Na2N3 Na3N4
Calcium and Chlorine?
CaCl Ca2Cl2 Ca2Cl
CaCl2 Ca3Cl4

12. Practice – cont’d What is the correct formula for a bond between…
Sodium and Hydroxide (OH) ? [hint: figure out the leftover charge from combining an oxygen an a hydrogen]
NaOH Na(OH)2 Na(OH)3
Na2(OH)3 Na(OH)4
Aluminum and Sulfate (SO4) ?
AlSO4 Al2(SO4)2 Al2(SO4)3
Al3(SO4)3 Al(SO4)4

13. Binomial Nomenclature
Naming a two-part name
Used to differentiate between Fluorine (an element) and Fluoride (part of a compound)
Never change the name of a Polyatomic Ion
Big difference between Sulfide and Sulfite

14. Naming Ionic Compounds
List the positive ion (or metal) first
***Use Roman Numerals to show the Oxidation number of a transition metal
Name the negative ion (or nonmetal), changing the ending to –ide
“Oxide”
“Sulfide”
“Phosphide”
Ex: FeO / Fe2O3
= Iron II Oxide / Iron III Oxide

15. Naming Polyatomic Compounds
Compound is polyatomic if there are more than 2 elements You will be given the names for common polyatomics.
Still only 2 words in the name
first term = positive ion name
second term = negative ion name
if second term is NOT a polyatomic, change ending to -ide
if the second term is a negative polyatomic, do NOT change the ending

16. Naming Covalent Compounds
Prefixes are used to show how many of which atoms
= number terms from Greek / Latin
Write the name of the cation [or most positive]
only add a prefix for the first atom if there is more than one
Write the name of the anion [or most negative]
add a prefix to tell how many are present
change the ending to -ide

17. Covalent Compounds Prefixes are used to show how many of which atoms
Prefixes are number-words from Greek & Latin
Write the name of the first atom
Add a prefix only if there is more than one of the first
Write the name of the second atom
Add a prefix showing how many of the second are present
Change the ending to -ide

18. Numbering Prefixes 1 – Mono- 2 – Di- 3 – Tri- 4 – Tetra-, 5 – Penta-
6 – Hexa-
7 – Hepta-
8 – Octa-
9 – Nona-
10 – Deka-

19. What is the name for N2O4? Nitrogen Oxide Dinitrogen Oxide
Dinitrogen Dioxide
Dinitrogen Tetraoxide
Nioxx (Nioxalate)

20. What is the name for Na2S? Sodium Sulfide Sodium Sulfite
Sodium Sulfate
Disodium Sulfide
Disodium Sulfate

21. What is the name for CO2? Carbon Oxide Carbon Dioxide Monocarbon Oxide
Monocarbon Dioxide
Mi-Bref (B-hot)

22. What is the name for (NH4)2O?
Nitrogen Hydrogen Oxide
Mononitrogen Tetrahydrogen Oxide
Ammonium Oxide
Diammonium Oxide
Ammonium Oxalate

23. Practice What is the name for N2O4? What is the name for Na2S?
non-metal + non-metal…so covalent
Dinitrogen Tetraoxide
What is the name for Na2S?
metal + non-metal = ionic
Sodium Sulfide
What is the name for CO2?
non-metal + non-metal = covalent
Carbon Dioxide

24. Practice – cont’d
What is the name for (NH4)2O? [hint: you need to know what (NH4) is…]
Nitrogen Hydrogen Oxide
Mononitrogen Tetrahydrogen Oxide
Ammonium Oxide
Diammonium Oxide
Ammonium Oxalate
CORRECT!!!!

25. Practice – cont’d
Al2S3 CrO Lead (II) oxide PbO2 (NH4)2S Ca(OH)2 Iron (II) cyanide Fe(NO3)3 Aluminum sulfide Chromium (II) oxide PbO Lead (IV) oxide Ammonium sulfide Calcium hydroxide Fe(CN)2 Iron (III) nitrate