Key Terms
Chemical equation
Symbolic representation of a chemical or physical change. Reactants: substances that undergo the change; written on the
Example
3 mol H2 + 2 mol Cl2 -> 2HCl Stoichiometric ratio is 1:1. H2:Cl2 actual ratio is 3:2 = 1.5:1.
Molecular equation
All species written as neutral formulas, even if ionic in solution.
Complete ionic equation
Dissolved ionic compounds written as dissociated ions. Solids, liquids, and gases stay in formula form (they do NOT diss
Net ionic equation
Spectator ions removed. Only species that actually change are shown.
Spectator ions
Ions present on BOTH sides unchanged. They exist only to maintain charge neutrality.
HOW TO PREDICT PRECIPITATION
Identify all ions in solution. Check every possible cation-anion pairing against the table.
Core definition
One or more elements undergo a change in oxidation number.
Acid
Dissolves in water to yield hydronium ions (H3O+). Strong acid: reacts COMPLETELY with water; essentially 100% ionized.
Weak acid
Reacts only PARTIALLY with water; most molecules stay in original form. Examples: acetic acid (vinegar, ~1% ionized), ci
Base
Dissolves in water to yield hydroxide ions (OH-). Strong base: ionic hydroxides that completely dissociate (NaOH, KOH, B
Oxidation
Increase in oxidation number (loss of electrons). "OIL"
Reduction
Decrease in oxidation number (gain of electrons). "RIG" OIL
RIG
Oxidation Is Loss, Reduction Is Gain. Oxidizing agent (oxidant): causes oxidation of something else; it GETS reduced.
Monatomic ion
Oxidation number = ion charge. (Na+ = +1; Cl- = -1) 3.