chemistry paper 1

• Compound


  A substance that contains two or more different types of atoms chemically bonded together
• Atoms change what they're bonded to and how they're bonded through chemical reactions
• Word equation


  A representation of a chemical reaction using words
• Chemical equation


  A representation of a chemical reaction using symbols
• Balancing a chemical equation

  1. Start balancing atoms that are only in compounds

  2. Balance carbons first

  3. Balance hydrogens

  4. Balance oxygens by doubling compounds

  5. Balance any remaining elements
• Mixture


  Any combination of any different types of elements and compounds that aren't chemically bonded together
• Mixtures


  • Air
  • Salt water
• Solution


  A mixture of a solute dissolved in a solvent
• Separating mixtures


  1. Filtration for large insoluble particles

  2. Crystallization for solutes

  3. Distillation for liquids with different boiling points
• Physical processes


  • Do not create new substances, only separate existing ones
• States of matter

  Solid, liquid, gas
• Melting and evaporation are physical changes that require energy to overcome intermolecular forces, not chemical reactions
• State symbols

  s for solid, l for liquid, g for gas, aq for aqueous (dissolved)
• Atom


  Consists of a positive nucleus with negative electrons orbiting it
• Plum pudding model of the atom

  • Positive charge with electrons dotted around it
• Rutherford's model of the atom

  • Positive nucleus with electrons orbiting relatively far away, mostly empty space
• Bohr's model of the atom


  • Electrons exist in shells or orbitals around the nucleus
• Protons


  Positive charges in the nucleus
• Neutrons


  Neutral charges in the nucleus
• Electrons


  Negative charges orbiting the nucleus
• Atomic number


  Number of protons in the nucleus
• Mass number


  Number of protons and neutrons in the nucleus
• Isotopes


  Atoms of the same element with different numbers of neutrons
• Relative abundance


  Percentage of each isotope in a sample
• Relative atomic mass (RAM)


  Average mass of all the isotopes of an element
• The periodic table was originally ordered by atomic weight, then later by atomic number and properties
• Electron configuration


  The arrangement of electrons in shells around the nucleus
• Sections of the periodic table

  • Metals to the left of the staircase
  • Non-metals to the right of the staircase
• Group


  The column an atom is in on the periodic table, indicates number of outer shell electrons
• Groups


  • Group 1 (alkali metals)
  • Group 7 (halogens)
  • Group 0 (noble gases)
• Alkali metals


  • Have one electron in outer shell which they readily donate
  • Reactivity increases down the group
• Halogens


  • Have seven electrons in outer shell which they readily accept
  • Reactivity decreases down the group
• Noble gases


  • Have full outer shells so are very unreactive
• Ion


  An atom that has gained or lost electrons, no longer electrically neutral
• Ion charges


  • Group 1 ions are 1+
  • Group 2 ions are 2+
  • Group 7 ions are 1-
  • Group 6 ions are 2-
• Transition metals


  • Can form ions with different charges
• Metallic bonding


  Bonding in metals where a lattice of positive ions is surrounded by delocalized electrons
• Metallic properties


  • Good conductors of electricity and heat
  • Malleable and ductile
• Ionic bonding


  Bonding between a metal and a non-metal where electrons are transferred
• Drawing ionic bonding diagrams

  1. Show outer shell electrons

  2. Indicate transfer of electrons

  3. Write formula and charges of ions