1. Writing Formulas The charges have to add up to zero.
Get charges on pieces.
Cations from name on table.
Anions from table or polyatomic.
Balance the charges by adding subscripts.
Put polyatomics in parenthesis.

2. Writing Formulas Write the formula for calcium chloride.
Calcium is Ca2+
Chloride is Cl1-
Ca2+ Cl1- would have a 1+ charge.
Need another Cl1-
Ca2+ Cl21- (use criss-cross method)

3. Write the formulas for these
Lithium sulfide
tin (II) oxide
tin (IV) oxide
Magnesium fluoride
Copper (II) sulfate
Iron (III) phosphide
gallium nitrate
Iron (III) sulfide

4. Write the formulas for these
Ammonium chloride
ammonium sulfide
barium nitrate

5. Things to look for
If cations have ( ), the number in parenthesis is their charge.
If anions end in -ide they are probably off the periodic table (Monoatomic)
If anion ends in -ate or -ite it is polyatomic

6. Section 6.5 Molecular Compounds and Acids
OBJECTIVES:
Apply the rules for naming and writing formulas for binary molecular compounds.

7. Section 6.5 Molecular Compounds and Acids
OBJECTIVES:
Name and write formulas for common acids.

8. Molecular compounds made of just nonmetals
smallest piece is a molecule
can’t be held together because of opposite charges.
can’t use charges to figure out how many of each atom

9. Molecular are easier!
Ionic compounds use charges to determine how many of each.
Have to figure out charges.
Have to figure out numbers.
Molecular compounds name tells you the number of atoms.
Uses prefixes to tell you the number

10. Prefixes (Table 6.5, p.159) 1 = mono- 2 = di- 3 = tri- 4 = tetra-
5 = penta-
6 = hexa-
7 = hepta-
8 = octa-

11. Prefixes
9 = nona-
10 = deca-
To write the name, write two words:

12. Prefixes Prefix name Prefix name -ide 9 = nona- 10 = deca-
To write the name, write two words:
Prefix
name
Prefix
name
-ide

13. Prefixes Prefix name Prefix name -ide 9 = nona- 10 = deca-
To write the name, write two words:
One exception is we don’t write mono- if there is only one of the first element.
Prefix
name
Prefix
name
-ide

14. Prefixes Prefix name Prefix name -ide 9 = nona- 10 = deca-
To write the name, write two words:
One exception is we don’t write mono- if there is only one of the first element.
No double vowels when writing names (oa oo)
Prefix
name
Prefix
name
-ide

15. Name These
N2O
NO2
Cl2O7
CBr4
CO2
BaCl2

16. Write formulas for these
diphosphorus pentoxide
tetraiodine nonoxide
sulfur hexafluoride
nitrogen trioxide
carbon tetrahydride
phosphorus trifluoride
aluminum chloride

17. Writing names and Formulas
Acids
Writing names and Formulas

18. Acids Compounds that give off hydrogen ions when dissolved in water.
Must have H in them.
will always be some H next to an anion.
The anion determines the name.

19. Naming acids
If the anion attached to hydrogen ends in -ide, put the prefix hydro- and change -ide to -ic acid
HCl - hydrogen ion and chloride ion
hydrochloric acid
H2S hydrogen ion and sulfide ion
hydrosulfuric acid

20. Naming Acids
If the anion has oxygen in it, then it ends in -ate of -ite
change the suffix -ate to -ic acid (use no prefix)
HNO3 Hydrogen and nitrate ions
Nitric acid
change the suffix -ite to -ous acid
HNO2 Hydrogen and nitrite ions
Nitrous acid

21. Name these HF
H3P
H2SO4
H2SO3
HCN
H2CrO4

22. Writing Acid Formulas Hydrogen will always be first
name will tell you the anion
make the charges cancel out.
Starts with hydro?- no oxygen, -ide
no hydro?, -ate comes from -ic, -ite comes from -ous

23. Write formulas for these
hydroiodic acid
acetic acid
carbonic acid
phosphorous acid
hydrobromic acid

24. Section 6.6 Summary of Naming and Formula Writing
OBJECTIVES:
Use the flowchart in Figure 6.21 to write the name of a compound when given its chemical formula.

25. Section 6.6 Summary of Naming and Formula Writing
OBJECTIVES:
Use the flowchart in Figure 6.23 to write a chemical formula when given the name of a compound.

26. Helpful to remember...
1. In an ionic compound, the net ionic charge is zero (criss-cross method)
2. An -ide ending generally indicates a binary compound
3. An -ite or -ate ending means there is a polyatomic ion that has oxygen
4. Prefixes generally mean molecular; they show the number of each atom

27. Helpful to remember...
5. A Roman numeral after the name of a cation shows the ionic charge of the cation
Use the handout sheets provided by your teacher!

28. Summary of Naming and Formula Writing
For naming, follow the flowchart- Fig. 6.21, page 161
For writing formulas, follow the flowchart from Fig. 6.23, p. 162