Paper 1

• Atom


  The different types or elements of atoms are represented in the periodic table by a symbol
• Compound


  A substance that contains two or more different types of atoms chemically bonded together
• If there's no number after a symbol, there's an invisible 1
• Chemical reactions


  Atoms change what they're bonded to and how they're bonded
• Word equation


  A way to represent a chemical reaction
• Chemical equation


  A way to represent a chemical reaction using symbols
• Atoms are not created or destroyed in any chemical reaction, so the same number of each type of atom must be on both sides of the equation
• Balancing chemical equations


  Start with atoms only in compounds, then balance other atoms by putting numbers in front of elements or compounds
• Mixture


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


  A mixture of a solute (solid dissolved in a liquid) and a solvent
• Separating mixtures


  1. Filtration (for large insoluble particles)

  2. Crystallization (to leave a solute behind after evaporating the solvent)

  3. Distillation (to separate liquids with different boiling points)
• These are physical processes, not chemical reactions, because no new substances are being made
• States of matter


  • Solid (particles vibrate around fixed positions)
  • Liquid (particles can move past each other)
  • Gas (particles are far apart and move randomly)
• Gases can be compressed, while solids and liquids cannot
• Melting and evaporation are physical changes that require energy to overcome the electrostatic forces of attraction between particles, but do not break chemical bonds
• Atomic models


  • JJ Thompson's plum pudding model
  • Rutherford's discovery of the nucleus and mostly empty space
  • Bohr's discovery of electron shells/orbitals
  • Chadwick's discovery of neutrons
• Protons, electrons, neutrons


  Protons and electrons have equal and opposite charges of +1 and -1 respectively, while neutrons have no charge
• Atomic number


  The number of protons in the nucleus, which determines the element
• Mass number


  The total number of protons and neutrons in the nucleus
• Isotopes


  Atoms of the same element with different numbers of neutrons
• The periodic table was originally ordered by atomic weight, then later grouped by properties
• Electron configuration


  The arrangement of electrons in shells/orbitals around the nucleus
• Periodic table sections


  • Metals (left of staircase)
  • Non-metals (right of staircase)
• Groups


  Columns in the periodic table that indicate the number of electrons in the outer shell
• Group names


  • Group 1 - Alkali metals
  • Group 7 - Halogens
  • Group 0 - Noble gases
• Ions


  Atoms that have gained or lost electrons, becoming positively or negatively charged
• Ion charges


  • Group 1 - +1
  • Group 2 - +2
  • Group 7 - -1
  • Group 6 - -2
• Ionic bonding


  Bonding between a metal atom that donates electrons and a non-metal atom that accepts electrons
• Covalent bonding


  Bonding between non-metal atoms that share electrons to gain full outer shells
• Simple molecular/covalent structures


  Individual molecules that can mix together, with relatively low boiling points
• Giant covalent structures


  Continuous networks of atoms bonded together, such as diamond and graphite, with high melting/boiling points
• Allotropes


  Different structural forms of the same element, like diamond and graphite
• Surface area to volume ratio

  The ratio of a particle's surface area to its volume, which is very high for nanoparticles
• Mole


  A specific number of atoms or molecules used to compare amounts of substances
• Balancing equations


  Ensuring that what goes in must come out
• Relative formula mass


  The sum of the relative atomic masses of the atoms in a compound
• CO2 has a relative formula mass of 44 (12 + 2 x 16)
• Gas product


  If it leaves the reaction vessel, will result in a seeming decrease in mass of the reactants
• Mole


  A specific number of atoms or molecules, used to compare amounts of substances
• If you have as many grams of a substance as its relative atomic or formula mass, you have one mole