chemical reactions

• Metals reacting with oxygen

  • Magnesium reacting rapidly with oxygen, releasing heat and light
  • Iron reacting slowly with oxygen over weeks or months
• Reaction of metals with oxygen

  Forms metal oxide
• Reaction of magnesium with oxygen

  Magnesium + Oxygen → Magnesium Oxide
• Reaction of iron with oxygen

  Iron + Oxygen → Iron Oxide
• Oxidation


  When a metal reacts with oxygen, the metal atoms have gained oxygen
• Oxidation


  Occurs when metals react with oxygen to form metal oxides
• Reduction


  The process of removing oxygen from a metal compound
• Magnesium oxide


  Can be split back into magnesium and oxygen, where the magnesium atoms are being reduced (losing oxygen)
• Reaction of calcium with copper oxide

  Calcium + Copper Oxide → Calcium Oxide + Copper
• In the reaction of calcium and copper oxide

  Calcium is oxidized (gains oxygen), copper is reduced (loses oxygen)
• Reaction of potassium with water

  1. Potassium reacts with water

  2. Produces potassium hydroxide

  3. Produces hydrogen gas
• Reaction of sodium with water

  1. Sodium reacts with water

  2. Produces sodium hydroxide

  3. Produces hydrogen gas
• Reaction of lithium with water

  1. Lithium reacts with water

  2. Produces lithium hydroxide

  3. Produces hydrogen gas
• Reaction of calcium with water

  1. Calcium reacts with water

  2. Produces calcium hydroxide

  3. Produces hydrogen gas
• Reactivity of metals with water

  • Potassium (most reactive)
  • Sodium
  • Lithium
  • Calcium
  • Magnesium
  • Zinc
  • Iron
  • Copper (least reactive)
• Reactivity of metals with dilute acids

  • Calcium (most reactive)
  • Magnesium
  • Zinc
  • Iron
  • Copper (least reactive)
• Reactivity series


  Order of elements based on their reactivity, used to predict the outcome of reactions
• Scientists usually include carbon and hydrogen in the reactivity series
• You are not expected to memorize the reactivity series, but you could be asked to construct one from data on how elements react
• When metals react


  They lose electrons and form positive ions
• Reactivity of metals


  Depends on their ability to lose electrons and form positive ions
• Metals at the top of the reactivity series readily form positive ions, while metals at the bottom are much less likely to form positive ions
• Active metal


  Metal found in the earth as the metal itself (e.g. gold)
• Oxide


  Compound of a metal with oxygen
• More reactive element will displace a less reactive element from its compound
• Reactivity series


  Elements ordered from most reactive to least reactive
• Extracting metal using carbon

  1. Carbon reacts with metal oxide

  2. Produces metal and carbon dioxide
• Reduction


  Loss of oxygen
• Oxidation


  Gain of oxygen
• Impossible displacement reaction


  • Zinc cannot displace calcium
• Possible displacement reactions


  • Magnesium displaces lithium (Mg reduced, Li oxidized)

  2. Copper displaces carbon (Cu reduced, C oxidized)
• Oxidation


  Loss of electrons
• Reduction


  Gain of electrons
• Equations involving the loss or gain of electrons are called half equations
• Identifying oxidation and reduction in a symbol equation


  Identify the ions present

  2. Determine which element has lost electrons (oxidation)

  3. Determine which element has gained electrons (reduction)
• Acid


  A chemical that produces hydrogen ions (H+) in aqueous solution
• Acids in aqueous solution

  • Produce hydrogen ions (H+)
• Base


  A chemical that can neutralize an acid, producing a salt and water
• Alkali


  A soluble base that produces hydroxide ions (OH-) in aqueous solution
• Alkalis in aqueous solution

  • Produce hydroxide ions (OH-)