1. Chapter 9 Chemical Names and Formulas
Mr. Roberts
Chemistry Level 2

2. Section 1 – Naming Cations
Group A Elements
Just write name of metal and add “ion” to ending
Example:
Na sodium ion
Al aluminum ion

3. Naming Cations Group B Elements (transition metals)
Ionic charge will change so write Roman Numerals in parenthesis after name of metal to indicate charge. (Stock System)
Table 9.2 page 255

4. Naming Cations
Some post transition element also have charges that will change.
Ex: Tin and Lead
Sn+2 Sn+4
Pb+2 Pb+4
Some transition metals only have one ionic charge. Therefore you don’t use roman numerals.
Silver Ag+1
Cadmium Cd+2
Zinc Zn+2

5. Naming Anions Always have the same charge! Change suffix with - ide
Ex: F-1 Fluoride ion
O-2 Oxide ion

6. Polyatomic Ions
Group of atoms that stay together and have an overall charge
Usually end with –ate or –ite (one less oxygen)
Ex: (SO3)-2 Sulfite
(SO4)-2 Sulfate
(NH4)+1 ammonium

7. Section 2 – Writing/Naming Ionic Compounds
Finding the formulas for ionic compounds.
Criss-Cross Method
Remember…ionic compounds must be expressed in the lowest whole number ratio.
Lose sign value

8. Naming Ionic Compounds
Binary Ionic Compounds (2 ions)
Use rules for naming ions
Ex: Na+1Cl-1 {sodium ion and chloride ion}
NaCl
Sodium Chloride

9. Naming Ionic Compounds (continued)
Naming Ternary Ionic Compounds (involving a polyatomic ion group)
Name it as it appears
Ex: CaCO3 calcium carbonate
Mg3(PO4)2 magnesium phosphate
CaSO4 calcium sulfate
If ammonium or any other polyatomic cation is reacting with a monatomic anion use binary ionic rules

10. Naming Group B Ionic Compounds
Rules for naming binary and ternary ionic compounds apply
Include a roman numeral in parenthesis to indicate the ionic charge.
Use the reverse of the criss cross method to determine the charge.
Ex:

11. Section 3 – Molecular Compounds
Naming Binary molecular compounds (2 nonmetals)
Name the elements in order they appear.
Drop ending of second element and replace with suffix “ide”.
Use prefixes to indicate # of atoms present
Table 9.4 page 269

12. Binary Molecular Compounds
Mono = 1 Di = 2 Tri = 3 Tetra = 4 Penta = 5 Hexa = 6 Hepta = 7 Octa = 8 Nona = 9 Deca = 10
Examples: N2O dinitrogen monoxide CO2 carbon dioxide CO carbon monoxide SF6 sulfur hexafluoride

13. 9.4 Naming and Writing Acids
Acid: a compound contain H+ ions.
Anion Ending
Acid Name
with Suffix
Acid Ending
Example
- ide
hydro________ic
acid
HCl – hydrochloric
- ite
____________ous
H2SO3 – sulfurous
- ate
_____________ic
H2SO4 – sulfuric

14. Examples
HF HClO2 HClO3
Hydrofluoric Acid
Chlorous Acid
Chloric Acid

15. Naming and Writing Bases
Base: a compound containing OH-1
Named in the same way as other ionic compounds
Example: NaOH sodium hydroxide

16. Section 9.5 – The Laws Governing Formulas and Names
We are able to name compounds and write their formulas because they form from elements in predictable ways

17. 1. The Law of Definite Proportions
In samples of any chemical compound, the masses of the elements are always in the same proportions.

18. 2. The Law of Multiple Proportions
Whenever the same two elements form more than one compound, the different masses of one element that combine with the same mass of the other element are in the ratio of small whole numbers.
John Dalton