Mocks Year 10

• 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
• Obtaining pure water from salt water


  1. Heat the solution so the water (solvent) evaporates

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


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


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


  • Particles move with fast speeds, high kinetic energy, far apart, can be compressed
• Rutherford's discovery about the atom

  Every atom is mostly empty space, with a small positive charge in the middle (the nucleus)
• Relative charge and mass of subatomic particles: Protons (+1), Neutrons (0), Electrons (-1)
• Atomic number


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


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

  First shell max 2, second shell max 8, etc.
• Ionic bonding


  Metals donate their outer electrons to leave an empty outer shell
• Ionic bonding


  Non-metal atoms accept electrons from metals to get a full outer shell, becoming negative ions
• Covalent bonding


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


  • Alkali metals (group 1)
  • Halogens (group 7)
  • Noble gases (group 0)
• Metallic bonding


  Metal atoms form a lattice with delocalized electrons, making them good conductors
• 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 vs diamond


  Graphite has delocalized electrons between layers, allowing conduction, while diamond has all electrons in covalent bonds
• Relative formula mass


  Sum of relative atomic masses of elements in a compound
• Limiting reactant


  The reactant that runs out first in a reaction
• Displacement reaction


  More reactive metal or non-metal takes the place of a less reactive one in a compound
• Oxidation and reduction


  Oxidation is loss of electrons, reduction is gain of electrons
• pH


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

  Need twice as many moles of NaOH as H2SO4, products are sodium sulfate and water
• Electrolysis of solutions


  Positive ions attracted to cathode (reduction), negative ions lose electrons at anode (oxidation)
• Products of electrolysis


  Determined by reactivity of dissolved ions and non-metals
• Corrosion


  Reaction of metals with oxygen, can be reduced by using a more reactive sacrificial metal
• Alloys


  Stronger than pure metals due to disruption of the atomic lattice
• Le Chatelier's principle


  System at equilibrium adjusts to counteract changes in concentration, pressure or temperature
• Calculating RF value in chromatography


  Ratio of distance moved by substance to distance moved by mobile phase
• Chemicals used in NPK fertilizers

  • Ammonia (N)
  • Phosphate rock (P)
  • Potassium chloride/sulfate (K)
• Electrons


  Exist in shells around the nucleus
• Electron configuration


  The arrangement of electrons in an atom's shells
• Modern periodic table


  Can be split into metals and non-metals by a staircase line
• Metals


  Atoms to the left of the staircase, they donate electrons
• Non-metals


  Atoms to the right of the staircase, they accept electrons
• Group


  The column an atom is in, tells you how many electrons in the outer shell
• Transition metals do not have their own group