1. Chemical Names and Formulas

2. Formulas of Binary Ionic Compounds
Composed fron only two elements: one metal and a nonmetal (NaCl, CaF2, FeCl3)
Group IA : +1 charge
Group IIA: +2 charge
Group IIIA: only Al 3+ charge
Group VIIA: -1 charge
Group VIA: -2 charge
Group VA: only N and P -3 charge.

3. Rule for writing binary ionic compounds
Cation always comes before the symbol of the anion.
Sum of the positive charges on the cation must equal the sum of the negative charges on the anions so that the formula of the compound is electrically neutral.
Whole numbers, writes as subscripts indicate the number of each ion in the formula unit.
The smallest set of numbers must be used.

4. Example: Fe3+ & Cl- Fe 3+ =3+ Cl-Cl-Cl- = 3- ---------------------
FeCl = 0 net charge

5. Another way
Use the size of the charges on the two ions to get the subscript numbers for the formula:

6. Example Problems:
Use the two ions to write a correct formula for an ionic compound
Mg2+ O2-
Na+ N3-
Hg22+ Cl-

7. Naming Binary Compounds
Using systemic names:
Single-cation metals: main group metals. Name of the cation followed by the name of the anion
Eg: Li+ : lithium ion, Ca2+: Calcium ion, Al3+: aluminum ion
Rules:
Name of the cation comes first
Cation is the name of the metal
the name of the anion ends in –ide
KBr: potassium bromide, Al2O3: aluminum oxide,
Na2S: sodium sulfide

8. Example Problems Correctly name these ionic compounds: LiCl & CaCl2
Mg3N2 & Na3N
AlP & AgCl

9. Naming Compounds w/ Multiple Cation Metals
Mostly used with transition metals because they are able to form two or more ions.
Uses the Stock System: name of the metal with its charge written as a Roman numeral.
Classical system: not common anymore, uses the –ous, -ic ending on the name of the metal to indicate the lower and higher charge.

10. Stock Name v. Classical Name
Copper Ion
Copper (II) ion
Mercury (I) ion
Mercury (II) ion
Chromium (II) ion
Chromium (III) ion
Cuprous ion
Cupric ion
Mercurous ion
Mercuric ion
Chromous ion
Chromic ion

11. Example Problems
Use the Stock method to name these ionic compounds involving multiple-cation metals
FeO & Fe2O3
CrCl3 & Hg2Cl2

12. Chemical Formula
Indicates the relative # of atoms of each kind in a molecular compound (covalent bond = single molecule) and in an ionic compound (ionic bond= one formula unit) CH4 (methane) NaCl (salt) How many atoms are in each compound? Pb(NO3)4 (lead (IV) nitrate)

13. Naming Monatomic Ions Al3+ is? Cl- is?
Cations  Elements name + cation
Al is?
Anions  Drop ending of elements name, add –ide + anion
Cl- is?

14. Binary Ionic Compounds
Compounds composed of 2 elements where the total number of + and – charges must be = (**in the smallest possible whole ratio though)
How would you name this??
(nomenclature)

15. Stock System of Nomenclature
Using a roman numeral to indicate an ion’s charge when there is more than one possible charge (cations)
No element forms more than one monatomic anion
How do you know the charge from a compound? Lithium is??
1 way is…
Li2O

16. Polyatomic Ion Compounds
Oxyanions: polyatomic ions that contain oxygen (usually can form more than 1 type)
2 types  -ite smaller # -ate larger #
3-4 types  hypo- plus -ite (smallest), -ite, -ate, per- plus -ate (largest)
Sulfate Ion

18. Naming Binary Molecular Compounds
2 systems used:
Old System = Prefix system of nomenclature
(see Page 269 for prefixes – memorize these)
PF5
Phosphorus pentaflouride
2. New System = Stock system (using oxidation numbers)

19. NOT ACTUAL physical characteristics of atoms
Oxidation Numbers
NOT ACTUAL physical characteristics of atoms
The number of electrons that must be added or removed from an atom in a combined state to convert the atom into the elemental form

20. Stock System vs Prefix System
Carbon dioxide
Carbon tetrachloride
Phosphorus pentachloride
Selenium hexafluoride
Arsenic pentaoxide

21. Assigning Oxidation Numbers
SEE HANDOUT!! Let’s try some together……

22. Common Binary Acids Acids that consist of two elements
Usually hydrogen + halogen
Oxyacids = Hydrogen ,oxygen, and a third element (nonmetal)
MEMORIZE = Hydrochloric acid, Phosphoric acid, Nitric acid, Sulfuric acid, Acetic acid, Carbonic acid (Pg 272 in textbook)

23. Law of Conservation of Mass
In all reactions, chemical or physical, mass is neither created nor destroyed Chemical reactions: Mass of products always equals mass of reactants

24. Law of Definite Proportions
The fact that a chemical compound contains the same elements in exactly the same proportions by mass regardless of the size of the sample or source of the compound Water is always: 11.2% H and 88.8% O

25. Law of Multiple Proportions
When elements combine, they do so in the ratio of small whole numbers For example carbon and oxygen react to form CO or CO2, but not CO g C g O = CO 1.00 g C g O = CO2

26. PRACTICE TIME!!

27. Chemical Quantities

28. Formula Masses
“Average mass”  sum of the average atomic masses of all atoms represented in its formula, whether it be a formula unit, molecule, or ion CO2 C = x 1 = amu O = x 2 = amu amu Let’s try some……..

29. Formula mass (amu) = Molar mass (g/mol)
Molar Masses
Molar mass = g/mol
Grams come from mass # on the periodic table
Grams # = 1 mol of the atom
So the molar mass of Chlorine is g/mol
Calculated like formula mass because…
Formula mass (amu) = Molar mass (g/mol)

30. Molar Mass Conversion Factor
Grams
Moles
Grams
Moles
Moles
Molecules
Grams = mass Moles = amount Molecules = number of atoms

31. Volume at STP 1 mol = 22.4 L (at STP)
Molar volume: The volume occupied by 1 mole of a gas at standard temperature and pressure
1 mol = 22.4 L (at STP)

32. Percentage Composition
Mass of element x 100 = % of element in Mass of compound compound Find element grams based on # of moles of each element in the compound. Find molar mass by addition of elemental gram results. “Plug” in the #’s to the formula…YAY!

33. Calculation of Empirical Formulas
Smallest atomic ratio possible
Change % (composition) to grams (mass composition)
Convert g to moles using molar mass conversion factor
Find ratio of smallest whole #’s by dividing each # of moles by smallest # of moles you have
Round decimals in ratios to nearest whole #
Time to Practice Again

34. Calculation of Molecular Formulas
Actual formula of molecular compound
x(empirical formula {mass}) = molecular formula {mass}
Therefore x = molecular formula mass
empirical formula mass