Chemical reactions

• Burning magnesium produces a white flame.
• When energy is given out, the reaction is exothermic.
• When energy is taken it, the reaction is endothermic.
• Many reactions are difficult to reverse.
• Alkali metal + water --> metal hydroxide + hydrogen
• Decomposition breaks down a compound to make 2 other ones.
• Decomposition caused by heat is thermal decomposition.
• Acid + base --> Salt + Water
• Precipitation: the sudden formation of a solid, either when two solutions are mixed or when a gas is bubbled into a solution.
• Displacement reactions occur because a more reactive element will displace a less reactive one from a solution of one of its compounds.
• Combustion: the reaction of a substance with oxygen causing the release of energy; it is exothermic and often involves a flame.
• The compound that is losing the oxygen is called the oxydizing agent.
• The compound that is gaining the oxygen is called the reducing agent.
• Oxidation is the loss of electrons.
• Reduction is the gain of electrons.
• All metals conduct electricity and graphite is the only non-metal that conducts.
• Electrolysis: the breakdown of an ionic compound, molten or aqueous in a solution, by the use of electricity.
• Electrodes are the metal rods made from graphite in electrolysis.
• The negative electrode is the cathode.
• The positive electrode is the anode.
• Electrolysis is the only method of extraction available for the most reactive metals.