1)Molecular  Form you are most familiar with  Reactants and products written as neutral compounds  Ex. KCl + NaF  NaCl + KF 3 Forms of Chemical Equations

2) Full Ionic  All chemical compounds are written as ions if they can be (ex. Strong electrolytes, strong acids, strong bases, etc.)  Ex. Ba Cl - + 2Na + + SO 4 -2  BaSO 4 (s) + 2Na + + 2Cl - Chemical Equations (cont. )Chemical Equations (cont. )

 Insoluble compounds are written as SOLIDS  Pure liquids and gases are written as is, not broken up into ions, electrically neutral.  Which compounds are broken up into ions????  Soluble ionic compounds  Strong acids (HCl, HBr, HI, HNO 3, HClO 4, H 2 SO 4 )  Strong Bases ( Group IA bases and Ca(OH) 2, Sr(OH) 2, Ba(OH) 2 How do we write a FULL IONIC equation?

3) Net Ionic Equations  Next step after full ionic equation.  Elimination of Spectator Ions (ions found on both sides of the equation, not changed with reaction)  Includes chemical compounds and ions DIRECTLY involved in chemical reaction. Forms of Chemical Equations (cont.)

Na 2 CO 3 + Ca(NO 3 ) 2  2NaNO 3 + CaCO 3 (s) Write net ionic equation Example 1:Example 1:

 Magnesium metal reacts with HCL to produce a solution of magnesium chloride and hydrogen gas.  Write the molecular equation and net ionic equation. Example 2:Example 2:

Oxidation-Reaction???? It’s more common than you think……..

Oxidation Numbers/StateOxidation Numbers/State  Allows us to identify redox reactions  A change in these numbers REDOX REACTION ! ! !  Acts like all chemical compounds are ionic----gives atom a charge it would have IF it was ionic

Oxidation NumbersOxidation Numbers  No physical meaning  Assigned to atoms to aid in redox reactions  Treats all atoms as if they were ions  ACTUAL charge of monoatomic ions, ASSIGNED charge to molecular atoms/atoms with a polyatomic ion

Oxidation Number RulesOxidation Number Rules  Priority 1 st, if there is ANY conflict—go with highest priority 1)Sum of oxidation numbers = 0 for ALL neutral compounds (atoms, molecules)  Any single atoms are also assigned oxidation # = 0

Rule # 1 ExamplesRule # 1 Examples  Br 2  MgCl 2  C 6 H 12 O 6  Cu  Ag  Fe

Oxidation Number RulesOxidation Number Rules 2) Sum of oxidation numbers for an ion = ion’s charge Examples:  SO 4 -2  NH 4 +  Al ion  Cl ion

Oxidation Number RulesOxidation Number Rules 3) Group 1A metals = +1 Group 2A metals = +2 Examples: MgSO 4 K 3 PO 4

Oxidation Number RulesOxidation Number Rules 4) For the majority of chemical compounds—  F = -1  H = +1 (sometimes will have -1)  O = -2 Examples: NH 3 H 2 O CO HF KF

Oxidation Number RulesOxidation Number Rules 5) Group 7A Elements = -1 Group 6A Elements = -2 Group 5A Elements = -3 **When combined with a metal in a binary compound !

Rule #5 ExamplesRule #5 Examples  CaF 2  Li 2 S  Mg 3 N  K 3 P

Ex 1. Al 2 O 3  Assign Oxidation Numbers

Ex. 2 K 2 Cr 2 O 7  Assign Oxidation Numbers

Calculate the oxidation number of Sulfur in the following: 1)S 8 6) SO 2 2)H 2 S7) SO 3 3)ZnS8) SO )SF 4 9) SO )SF 6 10) H 2 SO 4

Let’s Practice !Let’s Practice !  Strategy: assign oxidation numbers you know 1 st 1)Cr 2 O )CaH 2 3)KClO 4 4)Fe 3 O 4 5)Al 2 O 3 6)K 2 Cr 2 O 7