Ch 3

• Hydrates have a fixed number of water molecules, called the water of hydration
• The simplest chemical formula is the empirical formula
• Compounds with covalent bonds use molecular formulas, which include the condensed formula and the structural formula
• Chemica equations must be balanced to satisfy the law of conservation of matter
• Two methods of determining balancing equations: 1. inspection method 2. ion-electron method
• The ion-electron method is used for complex oxidation-reduction reacitons
• Combustion acronym: CHOcolate
• Double-replacement balancing: start with most complicated compound
• Properly balanced equations have the smallest whole number coefficients possible
• Net ionic equations get rid of spectator ions
• Reduction half-reactions are when electrons are added to the reactants side
• Oxidation half-reactions are when electrons are produced in the products side
• Nonmetals gain electrons which results in reduction reaction.
• Metals lose electrons which results in oxidation reaction
• Chemicals that undergo reduction themselves are oxidizing agents
• Chemicals that undergo oxidation themselves are reducing agents
• Nonmetals are oxidizing agents, metals are reducing agents
• Oxidation-reduction reactions involve the loss of electrons by one compound and the subsequent gain of the same electrons by another.
• Combustion and single-replacement reactions are oxidation-reduction reactions
• Elements that share electrons form covalent bonds
• Elements that transfer electrons form ionic bonds
• Noble gases are unreactive due to their completely filled s and p sublevels
• The representative elements are called the main group elements
• Representative elements are found in s and p blocks of the periodic table
• Nonrepresentative elements are found in the d and f blocks in the periodic table
• Representative metals lose electrons to form cations
• Representative metals in periods 4, 5, and 6 may lose only their p electrons to form multiple cations
• Representative nonmetals gain electrons to form anions
• Nitride: N3-
• Phosphide: P3-
• Carbide: C4-
• Cations of nonrepresentative elements arrange via their principal quantum number
• Many elements combine with oxygen to form polyatomic ions
• The law of electroneutrality states that the total positive charge of cations must be cancelled out by the total negative charge of anions
• Formulas of ionic compounds use empirical formula
• Aqueous solutions dissolve in water (aq)
• In the dissolution of ionic compounds:

  1.Only one cation and one anion are produced

  2.Charges of all ions must add up to zero

  3.Subscripts of monatomic ions become coefficients
• Solubility Rules:

  1.Compounds containing sodium or potassium cations or the ammonium ion are soluble

  2.Compounds containing nitrate anions are soluble
• Driving forces of chemical reactions:

  1. Water

  2. Weak electrolyte

  3. Precipitate

  4. Gas
• Net ionic equations remove spectator ions