Topic 4 - Chemical Changes

• What do metals react with to form metal oxides?

  Oxygen
• Why are these reactions called oxidation reactions?

  Because metals gain oxygen
• What is reduction in terms of oxygen?


  Loss of oxygen
• What is oxidation in terms of oxygen?

  Gain of oxygen
• What do metal atoms form when they react with other substances?

  Positive ions
• How is the reactivity of a metal related to its ions?

  It relates to forming positive ions
• What is the order of reactivity for the metals listed?

  • Potassium
  • Sodium
  • Lithium
  • Calcium
  • Magnesium
  • Zinc
  • Iron
  • Copper
• How does potassium react with water?

  Violently
• How does sodium react with water?

  Very quick
• How does lithium react with water?

  Quick
• How does calcium react with water?

  More slow
• How does calcium react with dilute acid?

  Very quick
• How does magnesium react with dilute acid?

  Quick
• How does zinc react with dilute acid?

  Fairly slow
• How does iron react with dilute acid?

  More slow
• How does copper react with dilute acid?

  Very slow
• Which non-metals are often included in the reactivity series?

  Hydrogen and carbon
• What can a more reactive metal do to a less reactive metal?

  Displace it from a compound
• Why is gold found as the metal itself?

  It is very unreactive
• How are most metals found in the Earth?

  As compounds
• How can metals less reactive than carbon be extracted?

  By reduction with carbon
• What does reduction involve in terms of oxygen?

  Loss of oxygen
• What does OIL RIG stand for?

  Oxidation Is Loss, Reduction Is Gain
• What happens to sodium when it is oxidised?

  It loses an electron
• What is the ionic equation for oxidised sodium?

  Na -> Na+ + e-
• What happens to sodium +1 ion when it is reduced?

  It gains an electron
• What is the ionic equation for reduced sodium?

  Na+ + e- -> Na
• What should the charges on each side of an ionic equation do?

  Add up to the same number
• In the equation 2Na + 2HCl -> 2NaCl + H2, which element is oxidised?

  Sodium
• What ions make up HCl?

  H+ and Cl- ions
• What ions make up NaCl?

  Na+ and Cl- ions
• What does the ionic equation 2Na -> 2Na+ + 2e- indicate about sodium?

  Sodium has lost electrons and is oxidised
• What does the ionic equation 2Cl- -> 2Cl- indicate about chlorine?

  Chlorine has not been oxidised or reduced
• What does the ionic equation 2H+ + 2e- -> H2 indicate about hydrogen?

  Hydrogen has gained electrons and is reduced
• What do acids react with to produce a salt and hydrogen?

  Some metals
• What is produced when an acid reacts with a metal?

  A salt and hydrogen
• What type of reactions are acid-metal reactions?

  Redox reactions
• How can you identify which substances are oxidized or reduced in a reaction?

  By looking at electrons gained and lost
• What does OIL RIG stand for in redox reactions?

  Oxidation Is Loss, Reduction Is Gain
• What is the ionic equation for magnesium oxidation?

  Mg -> Mg$^{2+}$ + 2e$^{-}$