1. States of Matter
The Particle Theory of Matter:
1. Matter is made up of tiny particles (Atoms & Molecules)
2. Particles of Matter are in constant motion.
3. Particles of Matter are held together by very strong electric forces
4. There are empty spaces between the particles of matter that are very large compared to the particles themselves.
5. Each substance has unique particles that are different from the particles of other substances
6. Temperature affects the speed of the particles.  The higher the temperature, the faster the speed of the particles.

2. Chemical Equations A chemical equation summarizes what happens to substances during a chemical reaction.
For example, the combustion of methane (in oxygen) is depicted as:
CH4(g) + 2 O2(g) → CO2(g) + 2 H2O(l)

3. Periodic Table of Elements The periodic table of elements arranges elements into periods (horizontal rows) and groups (vertical columns) according to their atomic numbers. The atomic number is the number of protons in an atomic nucleus. The entire table can be separated by metals (green), metalloids (pink) and non-metals (blue).

4. Predicting Chemical Reactivity Electron shell diagrams are useful because they show the numbers of electrons in the shells of atoms. Knowing the number of outer shell electrons helps you predict the formation of compounds, and write their chemical formulas. A chemical bond forms between two atoms when electrons in the outer shell of each atom form a stable arrangement together. The outer shell is called the valence shell. The electrons that occupy it are called valance electrons.

5. Positively Charged: Cations
Any atom or group of atoms that carries an electrical charge is called an ion. When a neutral atom gives up an electron, the positively charged ion that results is called a cation. Alkali metals form cations easily and are chemically very reactive.
When elements gain one electron they become negatively charged particles called anions.

6. Electron Dot Diagrams (Lewis Structures) In any group, all the elements have atoms with the same number of valence electrons. You can use a simple model called an electron dot diagram or Lewis diagram, to represent an atom and its valence electrons.

7. Forming Compounds
Atoms may share electrons between other atoms creating bonds. Substances that are composed of cations and anions are called ionic compounds. The attraction between the oppositely charged ions is called an ionic bond. Nearly all ionic compounds involve bonds between metal cations and non-metal anions.
Ionic compounds tend to have relatively high melting points because a large of amount of energy is needed to break the strong forces of attraction in ionic bonds.
Ionic compounds conduct electricity when they are molten or when they are dissolved in water. This is because the ions are able to move freely.
Ionic compounds in the solid state are not electrical conductors since the ions are not able to move

8. Forming Compounds
Atoms that share a pair of electrons are joined by a covalent bond. A neutral particle that is composed of atoms joined together by covalent bonds is called a molecule. Substances that are composed of molecules are called molecular compounds. Molecular compounds are formed when atoms of non-metals are joined by covalent bonds. Although the bonds between atoms within the molecule are strong, the force of attraction between the molecules is weak.
Molecular compounds have relatively low melting points because little energy is needed to break the forces of attraction between molecules.
Molecular compounds tend not to conduct electricity when they are in the solid or liquid state, or when they are dissolved in water, because they do non contain ions.

9. Is there a metal or a polyatomic ion present?
Chemical Names and Formulas
The system for naming an ionic compound is different from that for naming a covalent compound, so before a compound can be named, it must be classified as ionic or covalent.
Classifying a compound is not an easy task, but for the purposes of naming them, we employ a simple test:
Is there a metal or a polyatomic ion present?
A polyatomic ion consist of two or more different non-metal atoms, which are joined by covalent bonds.
If the answer is yes, use the system for naming ionic compounds. If the answer is no, use the system for naming covalent compounds.

10. Naming Ionic Compounds (continued)
If a Roman numeral is required, the charge on the metal ion must be determined from the charge on the negative ion.
Helpful Rules to Remember
A metal ion is always positive.
The Roman numeral indicates the charge, not the subscript.
The positive and negative charges must cancel (total charge must = 0).
Nonmetals are always negative & can never form more than one monatomic ion.
Examples
Formula
Reasoning
Name
FeCl2
Cl has a 1- charge, and there are 2 of them for a total of 2-, so the Fe must be 2+
iron (II) chloride
Fe2O3
O has a 2- charge, and there are 3 of them for a total of 6-, so the Fe must have a total charge of 6+ split equally between the two iron atoms, so each must have a 3+ charge
iron (III) oxide
PbS2
S has a 2- charge, and there are 2 of them for a total of 4-, so the Pb must be 4+
lead (IV) sulfide
Cu3N
N has a 3- charge, so the Cu must have a total charge of 3+ split equally between the 3 copper atoms, so each must have a 1+ charge
copper (I) nitride

11. Naming Ionic Compounds (continued)
II. Polyatomic ions each have specific names which must be memorized so they can be recognized on sight.
(At this point, if you are asked to name any compound that contains more than two elements, it will contain at least one polyatomic ion.)
A few of the more common polyatomic ions
Formula
Name
C2H3O21-
acetate
CO32-
carbonate
HCO31-
bicarbonate
NH41+
ammonium
Formula
Name
NO31-
nitrate
OH1-
hydroxide
PO43-
phosphate
SO42-
sulfate

12. Naming Ionic Compounds: Examples
Na2SO4
sodium sulfate
C2H3O21-
acetate
CO32-
carbonate
HCO31-
bicarbonate
NH41+
ammonium
NO31-
nitrate
OH1-
hydroxide
PO43-
phosphate
SO42-
sulfate
* Groups I & II, Al, Zn, Cd, and Ag need no Roman numeral.
Fe(NO3)2
iron (II) nitrate
AlCl3
aluminum chloride
PbI4
lead (IV) iodide
(NH4)3PO4
ammonium phosphate
Mg3N2
magnesium nitride
AgC2H3O2
silver acetate

13. Naming Covalent Compounds
Covalent compounds are named by adding prefixes to the element names.
The compounds named in this way are binary covalent compounds.
‘Binary’ means that only two atom are present.
‘Covalent’ (in this context) means both elements are nonmetals.
A prefix is added to the name of the first element in the formula if more than one atom of it is present. (The less electronegative element is typically written first.)
A prefix is always added to the name of the second element in the formula. The second element will use the form of its name ending in ‘ide’.

14. Naming Covalent Compounds
Prefixes
Subscript
Prefix 1
mono- 2
di- 3
tri- 4
tetra- 5
penta-
Subscript
Prefix 6
hexa- 7
hepta- 8
octa- 9
nona- 10
deca-
Note: When a prefix ending in ‘o’ or ‘a’ is added to ‘oxide’, the final vowel in the prefix is dropped.

15. Naming Binary Covalent Compounds: Examples1
mono 2 di 3
tri 4
tetra 5
penta 6
hexa 7
heptaa 8
octa 9
nona 10
deca
* Second element in ‘ide’ from
* Drop –a & -o before ‘oxide’
N2S4
dinitrogen tetrasulfide
NI3
nitrogen triiodide
XeF6
xenon hexafluoride
CCl4
carbon tetrachloride
P2O5
diphosphorus pentoxide
SO3
sulfur trioxide

16. Naming Compounds: Practice
SiF4
silicon tetrafluoride
Naming Compounds: Practice
two nonmetals  covalent  use prefixes
Na2CO3
sodium carbonate
metal present  ionic  no prefixes
Na  group I  no Roman numeral
Analysis
If “Yes”
* Is the cation a metal? (If so, does it need a Roman numeral?
The compound is ionic: name each ion present
(DO NOT USE PREFIXES)
* Is there a polyatomic ion present?
* Are both elements nonmetals?
The compound is covalent: use prefixes (NO CHARGES EXIST)
N2O
dinitrogen monoxide
two nonmetals  covalent  use prefixes
K2O
potassium oxide
metal present  ionic  no prefixes
K  group I  no Roman numeral
Cu3PO4
copper (I) phosphate
metal present  ionic  no prefixes
Cu  not group I, II, etc.  add Roman numeral (PO4 is 3-, each Cu must be 1+)
CoI3
cobalt (III) iodide
metal present  ionic  no prefixes
Co  not group I, II, etc.  add Roman numeral (I is 1-, total is 3-, Co must be 3+)
PI3
phosphorus triiodide
two nonmetals  covalent  use prefixes
NH4Cl
ammonium chloride
NH4  polyatomic ion present  ionic  no prefixes

17. Writing Chemical Formulas: A Review
I. Ionic Compounds
II. Covalent Compounds

18. Classifying Compounds
Classifying a compound using its name is not as difficult as using its formula.
The names of covalent compounds will be easily recognized by the presence of the prefixes (mono-, di-, tri-, etc.).
If no prefixes are present in the name, the compound is ionic. (Exception: some polyatomic ion names always contain prefixes (such as dichromate) but those will be memorized and recognized as ions.)

19. Writing Formulas for Ionic Compounds
Formulas for ionic compounds are written by balancing the positive and negative charges on the ions present.
The total positive charge must equal the total negative charge because the number of electrons lost by one element (or group of elements) must equal the number gained by the other(s).
Polyatomic ion names must still be recognized from memory (e.g. ammonium nitrate), but metals will have a Roman numeral associated with them if there is the possibility of more than one ion (e.g. copper (I) chloride or copper (II) chloride). The Roman numeral indicates the charge on the ion not the number of ions in the formula.

20. Writing Formulas for Ionic Compounds (continued)
Helpful Rules to Remember
A metal ion is always positive.
The Roman numeral indicates the charge, not the subscript.
The positive and negative charges must cancel (total charge must = 0).
If more than one polyatomic ion is needed, put it in parentheses, and place a subscript outside the parentheses.
Examples
Name
Reasoning
Formula
ammonium sulfate
NH4 has a 1+ charge & SO4 has a 2- charge, so 2 ammonium ions are required for each sulfate.
(NH4)2SO4
zinc chloride
Zn has a 2+ charge & Cl has a 1- charge, so 2 chloride ions are required for each zinc ion.
ZnCl2
copper (II) phosphate
Cu has a 2+ charge & PO4 has a 3- charge, so 3 copper (II) ions are required for every two phosphate ions.
Cu3(PO4)2

21. Writing Formulas for Covalent Compounds
The names of covalent compounds contain prefixes that indicate the number of atoms of each element present.
If no prefix is present on the name of the first element, there is only one atom of that element in the formula (its subscript will be 1).
A prefix will always be present on the name of the second element. The second element will use the form of its name ending in
Remember:
The compounds named in this way are binary covalent compounds (they contain only two elements, both of which are nonmetals).
When in covalent compounds, atoms do not have charges. Subscripts are determined directly from the prefixes in the name.

22. Writing Formulas for Binary Covalent Compounds: Examples1
mono 2 di 3
tri 4
tetra 5
penta 6
hexa 7
heptaa 8
octa 9
nona 10
deca
* Second element in ‘ide’ from
* Drop –a & -o before ‘oxide’
nitrogen dioxide
NO2
diphosphorus pentoxide
P2O5
xenon tetrafluoride
XeF4
sulfur hexafluoride
SF6

23. Writing Formulas: Practice
carbon tetrafluoride
CF4
Writing Formulas: Practice
prefixes  covalent  prefixes indicate subscripts
sodium phosphate
Na3PO4
Analysis
If “Yes”
The compound is covalent: the prefixes give the subscripts.
* Are there prefixes present
The compound is ionic: subscripts must be determined by balancing charges
metal  ionic  balance charges  3 Na1+ needed for 1 PO43-
copper (I) sulfate
Cu2SO4
metal present  ionic  balance charges 2 Cu1+ needed for 1 SO42-
aluminum sulfide
Al2S3
metal present  ionic  balance charges 2 Al3+ needed for 3 S2-
dinitrogen pentoxide
N2O5
prefixes  covalent  prefixes indicate subscripts
ammonium nitrate
NH4NO3
polyatomic ion present  ionic  balance charges 
1 NH41+ needed for 1 NO31-
lead (IV) oxide
PbO2
metal present  ionic  balance charges 1 Pb4+ needed for 2 O2-
iron (III) carbonate
Fe2(CO3)3
metal present  ionic  balance charges 2 Fe3+ needed for 3 CO32-

24. Chemical Equations and Chemical Reactions
During the late eighteenth century, Antoine Lavoisier conducted numerous experiments that involved chemical reactions. His belief in the need to make accurate measurements resulted in precise values for the masses of the substance in his experiments. Based on numerous observations of the same results, Lovoisier wrote his version of the law of conservation of mass: in every chemical reaction, there is an equal quantity of matter before and after the reaction.

25. Chemical Equations and Chemical Reactions
A chemical equation describes what happens in a chemical reaction. The equation identifies the reactants (starting materials) and products (resulting substance), the formulas of the participants, the phases of the participants (solid, liquid, gas), and the amount of each substance. Balancing a chemical equation refers to establishing the mathematical relationship between the quantity of reactants and products. The quantities are expressed as grams or moles.

26. H2 + O2 → H2O Writing Chemical Equations
It takes practice to be able to write balanced equations. There are essentially three steps to the process:
1. Write the unbalanced equation.
Chemical formulas of reactants are listed on the left-hand side of the equation.
Products are listed on the right-hand side of the equation.
Reactants and products are separated by putting an arrow between them to show the direction of the reaction. Reactions at equilibrium will have arrows facing both directions.
H2 + O2 → H2O

27. 2H2 + O2 → 2H2O Writing Chemical Equations 2. Balance the equation.
Apply the Law of conservation of Mass to get the same number of atoms of every element on each side of the equation. Tip: Start by balancing an element that appears in only one reactant and product.
Once one element is balanced, proceed to balance another, and another, until all elements are balanced.
Balance chemical formulas by placing coefficients in front of them. Do not add subscripts, because this will change the formulas. .
2H2 + O2 → 2H2O

28. 2H2(g) + O2(g) → 2H2O(l) Writing Chemical Equations
3. Indicate the states of matter of the reactants and products.
Use (g) for gaseous substances.
Use (s) for solids.
Use (l) for liquids.
Use (aq) for species in solution in water.
Write the state of matter immediately following the formula of the substance it describes.
2H2(g) + O2(g) → 2H2O(l)