Chemistry

• Elements


  Atoms that are the same
• Compounds


  2 or more different elements chemically
• Mixtures


  Different elements as compounds not chemically combined
• Molecules


  Any elements chemically converted
• Chemically combined
• Filtration


  1. Separate insoluble salill from liquids

  2. Use filter paper on filter funnel
• If we have a soluble solid in our liquid, it is actually dissolved
• Evaporation & Crystallisation


  1. Solution placed in evaporating dish on tripod and gently heated

  2. Solvent starts to evaporate

  3. Solution gets more concentrated

  4. Crystals form

  5. Solvent fully evaporates - dry crystals of solid
• Thermal decomposition


  Some solids will decompose when heated
• Crystallisation


  1. Place solution into evaporating dish, heat gently

  2. Some of the solvent has evaporated, see crystals forming

  3. Stop heating, allow to cool

  4. Crystals start to form

  5. Filter and dry the crystals
• Distillation


  1. Separate out components that have different boiling points

  2. Use a thermometer to measure temperature

  3. Heat up mixture, components evaporate and condense in the condenser

  4. Cooled vapour collects as liquid in the receiver
• Fractional distillation


  • Separating mixtures of liquids with similar boiling points
  • Use a fractionating column full of glass beads
  • Vapours cool at different heights in the column and condense
• Ethanol and Propanol vapour up, they will liquefy as the glass rods are cooler than their boiling point
• Most elements are metals and we find them towards the bottom left of the periodic table
• Metals


  • They form positive ions when they react
  • They have a full outer shell of electrons
• Non-metals


  Either don't form ions or they form negative ions
• To understand why metals form positive ions and non-metals form negative ions, we need to consider the electron arrangements of the atoms
• Elements on the left of the periodic table

  Won't have many electrons in their outermost shell
• Calcium


  Has two electrons in its outer shell, making it easy to lose these outer electrons and form a positive ion
• Chlorine


  Has seven electrons in its outer shell, would have to lose all seven to become a positive ion, which requires a lot of energy
• Metals become more reactive towards the bottom of the periodic table
• Metals


  • Have metallic bonding
  • Are malleable
  • Are good conductors of heat and electricity
  • Have high melting and boiling points
  • Are shiny
  • Are sonorous
• Non-metals


  • Tend to be dull in color
  • Are brittle
  • Have low melting and boiling points
  • Many are gaseous at room temperature
  • Are poor conductors of electricity
  • Generally have lower densities than metals
• Transition metals


  • Typical metal properties
  • Can form more than one ion
  • Their ions are often colored
  • Make very good catalysts
• Catalysts are substances which increase the rate of a chemical reaction without being used up themselves
• Catalysts used in important processes

  • Iron in the Haber process to make ammonia
  • Nickel in the hydrogenation of alkenes to make margarine
• Matter


  Comprises atoms and molecules
• Elements


  Basic units of matter
• Compounds


  Substances made up of two or more different elements
• Mixtures


  Combinations of two or more substances that are not chemically bonded
• Particle Theory


  • Explains how matter behaves at the atomic and molecular levels
  • Includes the arrangement and movement of particles in solids, liquids, and gases
• Atoms


  Basic units of elements, consisting of protons, neutrons, and electrons
• Atomic number


  Represents the number of protons in an atom's nucleus
• Mass number


  Accounts for both protons and neutrons in an atom
• Periodic Table


  • Organized into periods (rows) and groups (columns)
  • Exhibits group trends (similar chemical properties) and period trends (increasing atomic number and atomic mass)
• Periodic Trends


  • Atomic radius
  • Ionization energy
  • Electron affinity
  • Electronegativity
• Types of Chemical Reactions

  • Synthesis
  • Decomposition
  • Combustion
  • Single displacement
  • Double displacement
• Balancing Chemical Equations


  Ensure law of conservation of mass is upheld
• Arrhenius Definition of Acids and Bases

  Acids produce H+ ions in aqueous solutions; Bases produce OH- ions
• Bronsted-Lowry Definition of Acids and Bases

  Acids donate protons; Bases accept protons