Chemistry

• Compound


  A substance made from two or more elements chemically joined together
• Sodium chloride


  • Sodium
  • Chlorine
  • Sodium chloride
• Sodium chloride


  • Corrosive metal (sodium)
  • Toxic gas (chlorine)
  • Common salt!
• Two extremely dangerous substances combine to make something edible!
• Types of compound


  • Ionic
  • Covalent
  • Metallic
• Ionic compound


  Contains a metal and a non-metal, held together by ionic bonding
• Mixture


  Made of more than one substance, which are not chemically joined to each other
• Composition of air


  • Nitrogen
  • Oxygen
  • Argon
  • Carbon dioxide
• Measuring percentage of oxygen in air


  1. React air with another element

  2. Measure decrease in volume

  3. Calculate percentage of oxygen
• Solution


  A mixture of a liquid (solvent) with at least one other substance mixed through it
• Dissolving terminology


  • Solute
  • Solvent
  • Solution
  • Saturated
  • Suspension
  • Soluble
  • Insoluble
• Solubility


  Measured in g per 100 g of solvent
• Solubility can be scaled for different amounts of solvent
• Solubility curve


  • Line = saturated
  • Below = soluble
  • Above = insoluble
• Thermal decomposition


  1. Heat energy breaks down a substance

  2. Metal carbonate → Metal oxide + Carbon dioxide
• Thermal decomposition of copper carbonate

  • Copper carbonate → Copper oxide + Carbon dioxide
• Downward delivery


  Carbon dioxide is denser than air, so it sinks to the bottom of a tube
• Subatomic particles


  • Protons
  • Neutrons
  • Electrons
• Atomic number


  The number of protons
• Mass number


  The total number of protons and neutrons
• Isotopes


  Atoms with the same number of protons but different numbers of neutrons
• Relative atomic mass (RAM)

  The average mass of an atom of an element, taking into account the different masses of each isotope
• Electronic configuration


  Shows how electrons are arranged into energy levels
• Period


  Row on the periodic table, indicates number of occupied electron shells
• Group


  Column on the periodic table, indicates number of electrons in the outer-shell

  
• Forming metal ions


  1. Metal atoms lose outer-shell electrons to get a full outer-shell

  2. Become positively charged ions
• Forming non-metal ions


  1. Non-metal atoms gain electrons to fill their outer-shell

  2. Become negatively charged ions
• Oxidation


  Loss of electrons
• Reduction


  Gain of electrons
• Forming ionic compounds


  1. Metal atoms give electrons to non-metal atoms

  2. Atoms form ions with stable full outer-shells

  
• Monatomic ions


  • Na+
  • Mg2+
  • Al3+
  • Cl-
  • O2-
  • S2-
• Ionic formula


  Shows how many of each ion are present to balance the charges
• In any ionic compound, the charges balance: positive = negative
• Writing and balancing chemical equations

  1. Use word equations and chemical equations

  2. Balance equations to show same number and type of atoms on both sides
• Ionic structure


  • Ions arranged in a giant ionic lattice
  • Ions alternate + - + -
• Ionic bonding


  Electrostatic attraction between oppositely charged ions
• High melting points of ionic compounds

  • Ionic bonds are very strong
  • Lots of ionic bonds in a giant lattice
  • Breaking all bonds requires a lot of energy
• Ionic Structure: In an ionic compound, the ions are arranged in a giant ionic lattice
• Ionic Bonding: Ionic bonding is the electrostatic attraction between oppositely charged ions
• Ionic Bonding


  • It is always a very strong attraction