1. Chemistry 141
Lecture 6
Monday, September 18, 2017

2. Objectives for today Predict and write chemical formulas
Name chemical compounds
Write and balance chemical equations
Identify types of reactions (combination, decomposition, and combustion)

3. Ionic Compounds

4. Your turn
For each of the following pairs, predict the ionic compound they form
Mg and Cl
Fe(III) and O
K and N

5. Chemical Nomenclature
Common names (water, ammonia, etc.)
Ionic compounds
Cations
Group 1 and 2 metals (first 2 columns): same name as element
Transition metals
Add Roman numeral to denote charge: e.g. Fe3+  Iron (III)
Or, use Latin names: e.g. Fe3+  ferric ion, Fe2+  ferrous ion
Molecular cations tend to end in “ium”: e.g. NH4+  ammonium, H3O+  hydronium

6. Chemical Nomenclature
Common names
Ionic compounds
Cations
Anions
Monatomic anions: replace suffix with “ide”
Cl-  chloride
N3-  nitride
Polyatomic anions containing oxygen (oxyanions)
Most “common”  ends in “ate”
One less oxygen than “ate” version  ends in “ite”

7. Chemical Nomenclature
Common names
Ionic compounds
Cations
Anions
Monatomic anions: replace suffix with “ide”
Polyatomic anions containing oxygen (oxyanions)
Most “common”  ends in “ate”
One fewer oxygen than “ate” version  ends in “ite”
One more oxygen than “ate” version  starts with “per” / ends in “ate”
One fewer oxygen than “ite” version  starts with “hypo” / end in “ite”
ClO- = hypochlorite
ClO2- = chlorite
ClO3- = chlorate
ClO4- = perchlorate

8. Chemical Nomenclature
Common names
Ionic compounds
Cations
Anions
Monatomic anions: replace suffix with “ide”
Polyatomic anions containing oxygen (oxyanions)
Oxyanions containing hydrogen
One hydrogen: add “hydrogen” to start of name (add +1 to charge)
Two hydrogens: add “dihydrogen” to start of name (add +2 to charge)
PO43- = phosphate
HPO42- = hydrogen phosphate
H2PO4- = dihydrogen phosphate

9. Chemical Nomenclature
Common names
Ionic compounds
Cations
Anions
Compounds
LiF  ?
aluminum sulfite  ?
FeHPO4  ?

10. Chemical Nomenclature
Common names
Ionic compounds
Cations
Anions
Compounds
Hydrates (some ionic compounds include “waters of hydration”)
Use latin number prefix and add –hydrade (e.g. trihydrade)
FeCl3  iron (III) chloride
FeCl3 • 6H2O  iron (III) chloride hexahydrate

11. Chemical Nomenclature
Common names
Ionic compounds
Acids (anions with hydrogen cations (H+))
From anions ending in “ide”  prefix “hydro”, change “ide” to “ic acid”
From oxyanions
For oxyanions ending in “ate”  change “ate” to “ic acid”
For oxyanions ending in “ite”  change “ite” to “ous acid”
HI  hydroiodic acid
HNO3  nitric acid (H2SO4  sulfuric acid)
HClO  hypochlorous acid

12. Chemical Nomenclature
Common names
Ionic compounds
Acids
Binary molecular compounds
The leftmost (or bottom-most) element on the periodic table goes first
… unless it’s oxygen, which always goes last
… unless oxygen is paired with fluorine, and then it’s first again
The name of the second element is given the “ide” suffix
Use Greek prefixes (mono, di, tri, tetra, etc.) to indicate number of atoms
… but don’t use “mono” for first element
PCl5  phosphorous pentachloride
N2O3  dinitrogen trioxide

13. Chemical Nomenclature
Common names
Ionic compounds
Acids
Binary molecular compounds
Basic organic compounds
Alkanes (contain only C and H): CH4 = methane
Alcohols (contain an OH group): CH3OH = methanol
Organic acids (contain a COOH group): CH3COOH = acetic acid

16. Your turn For each pair below:
Predict the formula of the compound they form
Write the name of the compound
Ca and NO3-
Cr(III) and SO42-
NH4+ and S
H and PO43-
2 N’s and 5 O’s

17. The Law of Conservation of Mass
Matter cannot be created or destroyed
(Lavoisier, “The father of modern chemistry”, 1789)
“…an equal amount of matter exists both before and after the experiment. Upon this principle, the whole art of performing chemical experiments depends.”

18. CH4(g) + 2O2(g) CO2(g) + 2H2O(g)
States of matter
CH4(g) + 2O2(g) CO2(g) + 2H2O(g)
The states of the reactants and products are written in parentheses to the right of each compound.
(g) = gas
(l) = liquid
(s) = solid;
(aq) = in aqueous solution

19. Your turn
How many atoms of Mg, O, and H are represented by the notation 3 Mg(OH)2?
1 Mg, 2 O, and 2 H
2 Mg, 2 O, and 2 H
6 Mg, 6 O, and 6 H
3 Mg, 6 O, and 6 H
Answer: d

20. Balance the following equations:
TiCl4 (l) + H2O (l)  TiO2 (s) + HCl (aq)
AlCl3 (s) + Ca3N2 (s)  AlN (s) + CaCl2 (s)
C6H6 + O2  CO2 + H2O

21. Three Types of Reactions
Combination reactions
Decomposition reactions
Combustion reactions

22. Combination Reactions
In combination reactions two or more substances react to form one product.
2 Mg(s) + O2(g) MgO(s)

23. Decomposition Reactions
In a decomposition reaction one substance breaks down into two or more substances.
2 NaN3(s) Na(s) + 3 N2(g)

24. Combustion Reactions CH4(g) + 2 O2(g) CO2(g) + 2 H2O(g)
Combustion reactions most often involve oxygen in air as a reactant and can produce a flame.
CH4(g) + 2 O2(g) CO2(g) + 2 H2O(g)