1. Writing Chemical
Formulas

2. Chemical Formulas represent compounds.

3. Understanding Chemical
Formulas
Chemical formulas are composed of a positive half and a negative half.
Ex. - Water is a compound you know to have a formula of H2O.

4. The Easiest Way to write chemical formulas!
The easiest way to think of writing chemical formulas is to use the oxidation number (without the + or -) of one element as the subscript of the other element. (look at Periodic Table to get oxidation numbers) +2 -1
Ca Cl

5. Cross over the oxidation numbers without the charges!!!+2 -1
Ca Cl

6. Ca Cl 2
REMINDER: DO NOT write a subscript of 1. Reduce the subscripts if needed.

11. NAMING COMPOUNDS
Your ability to name compounds and write formula’s hinges on your ability to recognize whether a compound is Ionic or Molecular.

12. BINARY IONIC COMPOUNDS
Binary means 2 elements
Ionic means a metal and a non-metal (or cation and anion)
Writing Formulas
• charges must balance so
compound charge is neutral.

13. BINARY IONIC COMPOUNDS
Writing Formulas from Names
• 1st word = CATION
• 2nd word = ANION name
with ide ending.

14. BINARY IONIC COMPOUNDS
NaBr
MgF2
Sodium Bromide
Magnesium Fluoride

15. BINARY IONIC COMPOUNDS
Potassium Chloride
Aluminum Oxide
• notice ending of name is ide!
K+Cl- -> KCl Al23+O32- -> Al2O3

16. Polyatomic Ions
Definition •tightly bound groups of atoms that behave as a unit and carry a charge.
Example SO32-, NO2-, ClO2-

17. TERNARY IONIC COMPOUNDS
Ternary means 3 different elements
Usually contain Poly-atomic Ions
Ionic means cation and anion

18. TERNARY IONIC COMPOUNDS:Writing Formulas
Ca2+CO32- ->
CaCO3
Calcium Carbonate

19. TERNARY IONIC COMPOUNDS: Naming
Calcium Nitrate
Ca(NO3)2

20. Naming with Transition Metals
First word = CATION
Second word = ANION
• You need to determine what charge is on the transition metal if more than one exists.

21. Naming Transition Metals
Copper (I) Oxide
Cu2O

22. Writing Formulas with Transition Metals
FeCl3
FeCl2
Iron (III) Chloride
Iron (II) Chloride

23. TYPES OF COMPOUNDS Molecular Compounds
• composed of molecules in which elements share electrons.
• usually composed of nonmetals.
• these elements are attached

24. MOLECULAR FORMULA Definition kinds of atoms present in a
• shows the numbers and
kinds of atoms present in a
molecule of a compound.
i. e. CO

25. TYPES OF COMPOUNDS
Molecular Compounds con’t
•Examples
CS2
SiO2
BF3

26. BINARY MOLECULAR COMPOUNDS
Binary means 2 elements
Molecular means 2 non-metals
NO ionic charges are present

27. Naming Binary Molecular Compounds
Prefixes are used to show how many atoms are present in each molecule.
mono, di, tri,tetra, penta, hexa, hepta, octa, nona, deca

28. Writing Binary Molecular Compounds
Carbon Dioxide
• Di means 2 oxygens!!
CO •no mono prefix is used on first element

29. Naming Binary Molecular Compounds
2 ways it’s done!
• (prefix + element name)
i.e. N2O
dinitrogen monoxide

30. Naming Binary Molecular Compounds
• (prefix + element root + ide)
i.e. PCl3
Phosphorous Trichloride
All binary compounds end in ide!!!