Chemistry Ch 3

• Chemical formulas describe compounds
• Hydrates have a fixed number of water molecules, called the water of hydration
• Compounds in a hydrate are separated by a dot
• 1: mono
• 2: di
• 3: tri
• 4: tetra
• 5: penta
• 6: hexa
• 7: hepta
• 8: octa
• 9: nona
• 10: deca
• Ionic compounds use the empirical formula
• Covalent compounds use the molecular formulas. The molecular formulas include the condensed formula and the structural formula
• Other formulas include the ball and stick model or a space filling model
• Two methods for determining balanced coefficients: 1. inspection method 2. ion-electron method
• The ion-electron method is used for complex oxidation-reduction equations
• Balancing combustion: Chocolate
• Balancing double replacement: start with most complicated compound
• Properly balanced equations have the smallest whole number coefficients possible.
• Combustion reactions contain an organic compound that reacts with oxygen to form carbon dioxide and water
• An organic compound with sulfur will form SO2 under combustion
• Single-replacement reactions are reactions that replace one element with another.
• Double-replacement reactions are reactions where cations replace with each other
• Synthesis reactions occur when two or more elements form a compound
• Formation reactions occur when two or more elements form a compound with a coefficient of one. In these reactions, the coefficient of the reactants can be a fraction
• Addition reactions occur when a simple molecule or element is added to an entire molecule
• Decomposition reactions occur when a large molecule decomposes into its elements or into smaller molecules
• Net ionic equations get rid of spectator ions
• Half-reaction equations are used with oxidation-reduction reactions and electrochemical processes
• In reduction half-reactions, electrons are added to form ions
• In oxidation half reactions, electrons are removed from the ion
• Nonmetals tend to gain electrons, which results in reduction. Nonmetals are called oxidizing agents
• Metals tend to lose electrons, which results in oxidation. Metals are called reducing agents
• Oxidation-reduction reactions involve the loss of electrons by one compound and a gain of the same number of electrons by another.
• Combustion and single-replacement reactions are oxidation-reduction reactions
• Bonds form due to valence electrons
• The representative elements are called the main group elements and are those found in the s and p blocks of the periodic table
• Ions of representative elements are isoelectronic to noble gases