chemical changes

• what is oxidation

  the loss of electrons
• what is reduction

  gain of electrons
• what is created when a metal reacts with water

  a metal hydroxide and hydrogen are formed
• What happens to metal atoms when they react with other substances?

  Metal atoms lose electrons to form positive ions.
• What does the reactivity series of metals represent?

  It is a chart showing metals in order of decreasing reactivity.
• How does the reactivity of a metal affect its reactions?

  The more reactive a metal is, the more vigorous its reactions are.
• What is a characteristic of more reactive metals in terms of electron loss?

  More reactive metals lose electrons more easily to form positive ions (cations).
• What are the reactions of metals with cold water?

  • Potassium: Violent reaction
  • Sodium: Violent reaction
  • Lithium: Fast reaction
  • Calcium: Rapid reaction
  • Magnesium: Very slow reaction
  • Zinc: Usually no reaction
  • Iron: Rusts slowly
  • Copper: No reaction
  • Gold: No reaction
• What is formed when a metal reacts with water?

  A metal hydroxide and hydrogen are formed.
• What is an example of a metal reacting with cold water?

  Sodium reacts violently with cold water.
• What is produced when a metal reacts with dilute acids?

  A salt and hydrogen are formed.
• What happens when magnesium reacts with dilute hydrochloric acid?

  Magnesium reacts rapidly with dilute hydrochloric acid to produce hydrogen.
• What is the principle of displacement in solutions?

  A more reactive metal can displace a less reactive metal from its compounds.
• what happens when a metal reacts with a dilute acid

  a salt and hydrogen are formed
• Give an example of displacement in solutions involving magnesium and copper.

  Magnesium displaces copper from copper sulfate solution.
• What are unreactive metals found in the Earth's crust as?

  Uncombined elements
• How are most metals found in the Earth's crust?

  Combined with other elements to form compounds
• What is an ore?

  An ore is a rock that contains enough of a metal or a metal compound to make extracting the metal worthwhile
• Why are most metals extracted from ore?

  Because they are found combined with other elements
• What determines the extraction method used for a metal?

  The metal's position in the reactivity series
• What is the principle behind extracting any metal from its compounds?

  Using electrolysis
• Why is electrolysis considered expensive for metal extraction?

  Because large amounts of electrical energy are needed
• How can a metal less reactive than carbon be extracted from its compounds?

  By heating with carbon
• What is an example of a metal that can be extracted by heating with carbon?

  Copper
• What type of ores does copper mostly occur as?

  Sulfide ores
• How is copper produced from copper(II) oxide?

  By heating with carbon
• Why must aluminium be extracted using electrolysis?

  Because aluminium is more reactive than carbon
• Why is aluminium more expensive than iron despite being more abundant in the Earth's crust?

  Due to the large amounts of electrical energy used in the extraction process
• Anode

  The negative electrode where oxidation occurs.
• What is the first step in the electrolysis of aluminium oxide?

  Aluminium ore is treated to produce pure aluminium oxide
• What are the electrolytes used in electrolysis?

  Ionic compounds in the molten state or dissolved in water
• Why must aluminium oxide be molten to act as an electrolyte?

  Because it is insoluble in water
• What is the melting point of aluminium oxide and why is it significant?

  It is high, requiring a lot of energy to break its strong ionic bonds
• How is the cost of extracting aluminium reduced?

  By dissolving powdered aluminium oxide in molten cryolite
• What is the melting point of cryolite compared to aluminium oxide?

  Cryolite melts at a lower temperature than aluminium oxide
• What is required to melt cryolite during the extraction process?

  Significant amounts of energy
• Cathode

  The positive electrode where reduction occurs.
• what pH are acidic solutions

  values less than 7
• what pH are alkaline solutions

  values greater than 7
• what pH do neutral solutions have

  a value of 7