IB Chem 10

• Elements are made of atoms
• Elements are the simplest type of substance and cannot be broken down
• Compounds consist of two or more different elements that are chemically bonded
• Molecules are two or more atoms that are chemically joined
• Mixtures are two or more elements and/or compounds that are together but are not chemically bonded
• Homogenous mixtures have molecules evenly distributed
• Heterogeneous mixtures have molecules not evenly distributed
• Physical properties can be observed without producing a new substance
• Chemical properties can only be observed as a result of chemical change
• Physical properties are determined by use of the five senses and describe an object
• Examples of physical properties; boiling/condensation point, melting point, malleability, ductility, colour, state, solubility, luster, conductivity, hardness
• Physical properties are either qualitative or quantitative
• Qualitative physical properties are described but not measured
• Quantitative physical properties can be measured
• Chemical properties describe what a substance does as it changes (how it reacts and changes)
• Examples of chemical properties; corrosion, reaction with water/acids, flammability
• Five types of reactions:

  1. Synthesis
  2. Decomposition
  3. Single Displacement
  4. Double Displacement
  5. Combustion
• Synthesis is two elements joining together and forming a binary compound
• Two types of decomposition:

  1. A binary compound decomposing into elements
  2. Metal carbonate decomposing into a metal oxide and carbon oxide
• Single Displacement is a metal displacing another metal from an ionic compound (switch the element and the other corresponding metal/non-metal)
• For single displacement to occur, the single element must be higher in the activity series than the metal it is replacing
• Two types of single displacement:

  1. A metal displacing hydrogen from an acid (isolating hydrogen)
  2. A non-metal displacing another non-metal from an ionic compound (Determine the charges and criss-cross)
• NR = No reaction
• Double displacement only has a reaction that forms a solid when the products are not soluble in water
• Two types of double displacement:

  1. A reaction that forms a solid
  2. A reaction that forms a gas
• Sometimes, the production of a gas through double displacement, rather than a precipitate indicates that a double displacement reaction has occurred. This is actually two reactions that happen quickly. A double displacement occurs then one of the products quickly decomposes into water and a gas.
• Two elements -> Synthesis
• One compound -> Decomposition
• One element + one compound -> Single Displacement
• Two Compounds -> Double Displacement
• Combustion is the rapid reaction of a substance with oxygen to produce oxides and energy
• Oxygen is always a reactant in combustion
• Combustion involves a fuel burning or reacting quickly with oxygen
• Hydrocarbons are compounds that contain only the elements of hydrogen and oxygen and are typically used as fuel
• Complete Combustion occurs when a lot of oxygen is available and hydrocarbons are burnt completely
• Products available from complete combustion are CO2, H2O, and energy
• Complete Combustion = CxHy + O2 -> CO2 + H2O + Energy
• Complete combustion has a blue flame
• Incomplete combustion occurs when there is not enough oxygen
• Products available from incomplete combustion are CO (carbon monoxide), C (soot), CO2 (carbon dioxide) and H2O (water)