1. Naming Compounds Writing Formulas and Equations

2. Naming Compounds
The chemical formula represents the composition of each molecule.
In writing the chemical formula, in almost all cases the element farthest to the left of the periodic table is written first.
So for example the chemical formula of a compound that contains one sulfur atom and six fluorine atoms is SF6.
If the two elements are in the same period, the symbol of the element of that is lower in the group (i.e. heavier) is written first e.g. IF3.

3. Naming Ionic Compounds
Ionic compounds are combinations of positive
and negative ions.
In writing the chemical formula the positive ion is
written first, It is then followed by the name of the
negative ion.
Monatomic anions end in ide. Special endings
apply for polyatomic ions
Examples
NaCl Sodium chloride
BaF2 Barium Fluoride
ZnO Zinc Oxide

4. Names of Polyatomic Ions with Oxygen
ClO-
hypochlorite
ClO2-
chlorite
ClO3-
chlorate
ClO4-
perchlorate
NO2-
Nitrite 
NO3-
Nitrate 
PO33-
phosphite 
PO43-
phosphate 
SO32-
SO42-
sulfite 
sulfate 
Polyatomic ions usually contain oxygen in addition to another element. 
Normally they have a negative charge. 
They end in either "ate" or "ite" depending on the number of oxygen atoms present.

5. Polyatomic Ion -- Exceptions
Most polyatomic ions contain oxygen
Their names end in “ite” or “ate”.
There are several exceptions
OH hydroxide
CN cyanide
SCN thiocyanate

6. Elements with Multiple Cations
When an element can form more than one cation a Roman numeral is used to distinguish the oxidation state of the compound.
Iron, Tin, Lead, Copper, and are common elements with more than one cation.
Examples
PbSO4  =  lead (II) sulfate   This compound is formed from Pb2+ and  SO42-
Pb(SO4)2 =  lead (IV) sulfate   This compound is formed from Pb4+ and  SO42-
Fe(OH)2  =  iron (II) hydroxide   This compound is formed from Fe2+ and  OH- 
Fe(OH)3  =  iron (III)  hydroxide    This compound is formed from Fe3+ and  OH-

7. Examples of Ionic Compounds
NaCl = Sodium chloride
ZnF2 = Zinc fluoride
KOH = Potassium hydroxide
Ca(NO3)2 = Calcium nitrate
BaSO3 = Barium Sulfite
Al2(SO4) 3 = Aluminum sulfate
Ca3(PO3)2 = Calcium phosphite
NH4Cl = Ammonium chloride
(NH4)2CO3 = Ammonium carbonate

8. Naming Covalent Compounds
When naming covalent compounds, the name of the first element in the formula is unchanged.
The suffix “-ide” is added to the second element.
Often a prefix to the name of the second element indicates the number of the element in the compound
Examples:
SF6 – sulfur hexafluoride
P4O10 – tetraphosphorous decoxide
CO – carbon monoxide
CO2 – carbon dioxide

9. Covalent molecules with multiple possibilities
A Roman Numeral is used to indicate the state of the more positive element
Examples
N2O   =  Nitrogen (I) oxide   Since oxygen has a 2- charge, the nitrogen must be 1+ to  balance the charges.    Also known as dinitrogen monoxide
N2O3 =  Nitrogen (III) oxide    Since oxygen has a 2- charge, the nitrogen must be 3+ to balance the charges  Also  known as dinitrogen trioxide

10. Binary compounds of Hydrogen
The binary compounds of hydrogen are special cases. They were discovered before a convention was adopted and hence their original names have stayed.
Water H2O is not called dihydrogen monoxide
Hydrogen forms binary compounds with almost all non-metals except the noble gases.
Examples
HF - hydrogen fluoride
HCl - hydrogen chloride
H2S - hydrogen sulfide

11. Acids
When many hydrogen compounds are dissolve in water they take on the form of an acid. Special rules apply to acids. The “ite” suffix becomes “ous” and the “ate” suffix becomes “ic”
HCl
Hydrochloric Acid
Cl-
Chloride
HNO2
Nitrous Acid
NO2-
Nitrite
HNO3
Nitric Acid
NO3-
Nitrate
H2SO3
Sulfurous Acid
SO32-
Sulfite
H2SO4
Sulfuric Acid
SO42-
Sulfate
H3PO3
Phosphorous Acid
PO33-
Phosphite
H3PO4
Phosphoric Acid
PO43-
Phosphate
H2CO3
Carbonic Acid
CO32-
Carbonate

12. Writing Formulas for Ionic Compounds
Write the positive ion (cation) first, then the negative ion.
The positive charges must balance the negative charges.
Use subscripts to show how many times each ion must appear in order for the charges to balance. A subscript is not used if the ion appears only once
Use parenthesis around polyatomic ions that appear more than once in the formula

13. Examples Na+ and Cl- = NaCl Zn2+ and Br- = ZnBr2 K+ and OH- = KOH
Ca2+ and OH = Ca(OH)2
Fe2+ and SO = FeSO4
Fe3+ and SO = Fe2(SO4) 3
Ca2 + and PO = Ca3(PO4)2
NH4+ and Cl = NH4Cl
NH4+ and CO = (NH4)2CO3

14. Chemical Reactions
Elements and compounds frequently undergo chemical reactions to form new substances
In a chemical reaction, chemical bonds are frequently broken and new chemical bonds are formed
Atoms are neither created nor destroyed in an ordinary chemical change

15. Chemical Reactions
A balanced chemical reaction is used to describe the process that occurs in a chemical change.
For example: Zinc reacts with hydrochloric acid to produce zinc chloride and hydrogen gas.
This chemical reaction could be written as
Zn HCl  ZnCl H2

16. Reactants and Products
In the chemical reaction
Zn HCl  ZnCl H2
Reactants Products
This shorthand way of describing a chemical reaction is known as a chemical equation
The starting materials are shown on the left and are known as reactants
The substances formed are shown on the right and are known as the products

17. Balancing a Chemical Reaction
A proper chemical reaction must be balanced
Zn HCl  ZnCl H2
Reactants Products
Each element must appear on both sides of the arrow and equal number of times
Chemical reactions can be balanced by inserting numbers in front of formulas.
These numbers are called coefficients

18. Balancing Chemical Reactions
Most simple equations can be balanced by inspection
Example: Balance the following equation
BaCl2 + K3PO4  Ba3 (PO4)2 + KCl
There are 3 Ba on the right so we need coefficient of 3 in front of BaCl2
There are 2 PO4 on the right so we need a coefficient of 2 in front of K3PO4.
This leaves 6 K on the left so we need a coefficient of 6 in front of the KCl on the right
The balanced equation is
3 BaCl K3PO4  Ba3 (PO4) KCl

19. Balancing Chemical Reactions
An equation is balanced when there are the same number and kind of atoms on both sides of the arrow
3 BaCl K3PO4  Ba3(PO4) KCl
Reactants (Left)
Products (Right)
Ba 3
Ba 3
Cl x 2 = 6 Cl
K x 3 = 6 K P P
O x 4 = 8
O x 4 = 8

20. State Symbols Symbols (s) Solid (l) Liquid (g) Gas (aq)
State symbols are often added to chemical equations.
CaCO3 (s) + 2 HCl (aq)  CaCl2 (aq) + CO2 (g) + H2O (l)
Symbols
(s)
Solid
(l)
Liquid
(g)
Gas
(aq)
Aqueous (Water Solution)

21. Types of Reactions
There are many kinds of chemical reactions that occur. Some are very simple while others are very complex and may occur in multiple steps.
A number of reactions conform to some relatively simple patterns
Understanding and identifying these patterns can be helpful in predicting the products of similar reactions

22. Direct Combination
In a direct combination, two elements or compounds combine to form a more complicated product
Examples
CaO + CO2  CaCO3
2 H2 + O  2 H2O
FeCl2 + Cl2  FeCl3
N O  2 NO

23. Decomposition
In a dcecomposition, a single compound is broken down into two or more simplier substances
Examples
2 KClO3  2 KCl O2
ZnCO3  ZnO + CO2
Cu(OH)2  CuO H2O

24. Single Replacement
In a single replacement, one substance (usually an element) takes the place of another in a compound
Examples
Zn H2SO4  ZnSO H2
Cl KBr  2 KCl + Br2
Mg + CuCl2  MgCl Cu

25. Double Replacement
In a double replacement, two substances exchange places in their respective compounds
Examples
AgNO3 + NaCl  AgCl + NaNO3
3 CaCl K3PO4  Ca3(PO4)2 + 6KCl BaCl2 + Na2SO4  BaSO4 + 2NaCl

26. Diatomic Molecules Hydrogen Fluorine Oxygen Iodine Chlorine Bromine
Certain elements exist as diatomic molecules in nature H2
Hydrogen N2
Nitrogen F2
Fluorine O2
Oxygen I2
Iodine
Cl2
Chlorine
Br2
Bromine

27. Diatomic Molecules Hydrogen Have Nitrogen No Fluorine Fear Oxygen Of
Certain elements exist as diatomic molecules in nature H2
Hydrogen
Have N2
Nitrogen No F2
Fluorine
Fear O2
Oxygen Of I2
Iodine
Ice
Cl2
Chlorine
Cold
Br2
Bromine
Beer