chemistry end of unit test

• What happens to boiling and melting points as you go down Group 0?


  They increase.
• What is the characteristic of Group 0 gases?


  They are colourless and unreactive.
• Why are noble gases considered unreactive?


  They have a full outer shell of electrons.
• What is an ore?


  An ore is a rock that contains enough metal to be extracted.
• What do you do if a metal is less reactive than carbon?


  You react it with carbon to extract it.
• What method is used to separate more reactive metals from their ores?


  Electrolysis.
• How is the rate of a reaction measured?


  By how much reactant is used up or how much product is formed.
• What factors increase the rate of a chemical reaction?


  Higher temperature, concentration, surface area, and gradient of the run.
• What is activation energy?


  It is the minimum energy needed for particles to react.
• What role do enzymes play in reactions?


  They increase the rate of reaction without being chemically changed.
• What is an exothermic reaction?


  It releases energy, shown by a rise in temperature in the surroundings.
• What is an endothermic reaction?


  It absorbs energy, shown by a fall in temperature in the surroundings.
• What does the height of the hump on a reaction graph represent?

  The activation energy needed to break one mole of bonds.
• How do you calculate bond energy in an exothermic reaction?


  By subtracting the energy in from the energy out.
• What happens when the energy out is greater than the energy in?

  The reaction is exothermic and has a negative energy change.
• What is the reactivity trend of halogens as you go down Group 7?


  Reactivity decreases.
• How can you test for chlorine gas?


  Using damp blue litmus paper, which turns red.
• What is a displacement reaction in the context of halogens?


  A more reactive halogen will displace a less reactive one.
• What are the properties of alkali metals in Group 1?


  • Soft
  • Low melting and boiling points
  • Form 1+ ions
  • 1 electron in the outer shell
  • Reactivity increases as you go down the group
• What is the reaction equation for sodium reacting with water?


  2Na + 2H₂O → 2NaOH + H₂
• What happens to the reactivity of alkali metals as you go down the group?


  It increases.
• What is the general reaction of potassium with water?


  It reacts very hot.
• What is the general reaction of sodium with water?


  It reacts very hot.
• What is the general reaction of lithium with water?


  It fizzes and warms.