chemistry paper 1 quiz

• Element


  Substance made from only one type of atom
• Compound


  Substance made from two or more different types of atoms chemically bonded together
• Mixture


  Two or more different elements or compounds that are not chemically bonded together
• Balancing chemical equation

  1. Can't change the little numbers

  2. Balance phosphorus by putting 2 on the right

  3. Balance oxygen by putting 3 in front of O2 on the left
• Distillation to get pure water from salt water

  1. Heat solution so water (solvent) evaporates

  2. Use condenser to turn water vapour back into liquid, leaving salt (solute) behind
• Solid


  • Particles vibrate about fixed positions, tightly packed, cannot be compressed
• Liquid

  • Particles free to move past each other, still touching, cannot be compressed
• Gas


  • Particles move with fast speeds, high kinetic energy, far apart, can be compressed
• Rutherford discovered that atoms are mostly empty space with a small, positive charge in the middle (nucleus)
• Subatomic particles


  • Protons (positive charge, relatively same mass as neutrons)
  • Neutrons (neutral charge, relatively same mass as protons)
  • Electrons (negative charge, very small mass)
• Atomic number


  Number of protons in the atom's nucleus
• Mass number (relative atomic mass)


  Number of protons plus neutrons in the nucleus
• Electron shell filling in atoms up to calcium

  1. First shell max 2 electrons

  2. Second shell max 8 electrons

  3. Etc.
• Ionic bonding


  Metals donate their outer electrons to non-metals, leaving them with a positive charge
• Covalent bonding


  Non-metals share electrons to get a full outer shell
• Reactivity groups


  • Alkali metals (group 1, very reactive)
  • Halogens (group 7, get more reactive up the group)
  • Noble gases (group 0, very unreactive)
• Metallic bonding


  Metal atoms form a lattice with a 'sea' of delocalized electrons, making them good conductors
• The formula for iron(III) oxide is Fe2O3
• Drawing structural formula and dot-and-cross diagram for methane

  1. Carbon makes 4 covalent bonds to hydrogen

  2. Structural formula shows bonds as lines, dot-and-cross shows electron pairs
• Properties of ionic compounds

  • High melting points, can only conduct electricity when molten or dissolved
• Properties of simple covalent compounds

  • Relatively low melting and boiling points, cannot conduct electricity
• Graphite can conduct electricity, diamond cannot, even though they are both carbon allotropes
• The relative formula mass of magnesium hydroxide is 58 g/mol
• 29 g of magnesium hydroxide is equivalent to 0.5 moles
• 72 g of water is needed to make 116 g of magnesium hydroxide
• Limiting reactant


  The reactant that runs out first in a reaction
• 23.4 g of sodium chloride is needed to make a 0.2 mol/dm3 solution in 2 dm3 of water
• Percentage yield


  Used when given actual masses of reactants and products
• Atom economy


  Uses relative atomic masses to find how much of a desired product is made compared to total reactants
• Displacement reaction


  A more reactive metal or non-metal takes the place of a less reactive one in a compound
• Oxidation


  Loss of electrons
• Reduction


  Gain of electrons
• pH


  Measure of H+ ion concentration, lower pH is more acidic, higher pH is more alkaline
• Neutralisation of sulfuric acid with sodium hydroxide


  1. Need 6 moles of NaOH to neutralise 3 moles of H2SO4

  2. Products are sodium sulfate and water
• Electrolysis of solutions


  1. Positive ions attracted to negative cathode, gain electrons (reduction)

  2. Negative ions attracted to positive anode, lose electrons (oxidation)
• Exothermic reaction


  Reaction releases energy, so temperature increases
• Endothermic reaction


  Reaction absorbs energy, so temperature decreases