1. Chemical Formulas and Chemical Compounds
Chapter 7

2. Chemical Formulas Octane Molecule Aluminum Sulfate formula unit C8H18
Al2(SO4)3

3. Monatomic Ions Def: ions formed from a single atom Naming ions
Cation – use element name
Anion – change ending of element to -ide

4. Monatomic Ions d – block elements and others with multiple ions
Use Roman numeral in name
Fe+3  Iron(III) ion
Fe+2  Iron(II) ion
Metals always have positive charge

6. Polyatomic Ions

7. Polyatomic Ions NO3-  Nitrate NO2-  Nitrite
The –ate means 1 more oxygen
SO4-2  Sulfate
SO3-2  Sulfite

8. Polyatomic Ions ClO4-  Perchlorate ClO3-  Chlorate ClO2-  Chlorite
ClO -  Hypochlorite

9. Binary Ionic Compounds
Def: composed of 2 elements
Total (+) charge must = total (-) charge
Write the formula:
Mg and Cl
K and N
Al and O

10. Compounds with Polyatomic Ions
Iron(II) and Nitrite
Boron and Perchlorate
Ammonium and Oxygen

11. Naming Ionic Compounds
Name the cation first, then the anion
NaOH
RbCl
Ag2SO3
Fe3N2
Al(MnO4)3

12. Writing Formulas Potassium sulfide Copper(II) sulfate Sodium carbonate
Calcium chloride

13. Naming Binary Covalent Compounds
CO, CO2
We use PREFIXES in the name!!

14. Prefixes Mono- One Hexa- Six Di- Two Hepta- Seven Tri- Three Octa-
Eight
Tetra-
Four
Nona-
Nine
Penta-
Five
Deca-
Ten

15. Covalent Naming Rules Use prefixes to show how many of each element
Single atom in first element, mono is not used
The second element name ends in –ide
Drop vowel at end of prefix if element begins with vowel (except: di and tri)

16. Examples N2O4 PCl5 Nitrogen Dioxide Boron Trifluoride
Diphosphorus Pentoxide

17. Naming Acids 2 types of acids:
1. Oxyacids: hydrogen and polyatomic ion
2. Binary Acids: hydrogen and halogen

18. Naming Oxyacids Replace ending of anion name Anion Suffix Acid Suffix
- ite ous
- ate ic

19. Naming Oxyacids H2SO4  anion SO4-2  Sulfuric Acid
H2SO3  anion SO3-2  Sulfurous Acid
HClO4
HNO3

20. Naming Binary Acids Hydrogen and a halogen Use prefix hydro-
Use suffix –ic
Followed by acid

21. Naming Binary Acids
HCl HF HI
HBr

22. Formula Mass
Mass of H2O?
Formula Mass: mass of molecule, formula unit, or ion is sum of masses of all atoms represented (amu)
Ca(NO3)2

23. Molar Mass
Def: mass of 1 mole of compound – use molar masses of elements (g/mol)
(NH4)2CrO4

24. Molar Mass in Conversions
Remember flow chart??
What is mass (g) of 3.04 mol of ammonia vapor, NH3?
How many molecules are in 4.15 x 10-5g C6H12O6?

25. More Conversions How many H atoms are in 7.1 moles of C6H12O6?
How many formula units are in 4.5 kg Ca(OH)2?
What is the mass of H2SO4, if you have 1.53 x 1023 sulfate ions your compound?

26. Percent Composition A basket of fruit = 120 g 3 apples = 50 g
2 oranges = 35 g
2 bananas = 20 g
Basket = 15 g
What percentage of the basket’s mass is from the apples?

27. Percent Composition
What is the percent composition by mass of each element in (NH4)2O?
What percentage by mass of Al2(SO4)36H2O is water?

28. Empirical Formula
Def: formula showing smallest whole-number mole ratio
Ex: B2H6  Molecular Formula
BH3  Empirical Formula

29. Finding Empirical Formula
Determine the empirical formula of the compound with 17.15% C, 1.44% H, and 81.41% F.
CHF3

30. Finding Empirical Formula
Find empirical formula of 26.56% K, 35.41% Cr, and rest O.
K2Cr2O7

31. Finding Molecular Formula
x(empirical formula) = molecular formula
x(Emp.Form Mass) = Molec.Form Mass
x = Molecular Mass
Empirical Mass

32. Finding Molecular Formula
Determine molecular formula of compound with empirical formula CH and formula mass of amu.

33. Finding Molecular Formula
Sample has formula mass of amu has 0.44g H and 6.92g O. Find its molecular formula.