chem

• 0 3 . 2 Explain why diamond has a very high melting point.

  bonds are strong

  bonds need to be broken

  so lots of energy is required
• 0 3 . 1 Describe the structure and bonding of diamond.

  giant srtucutre

  covalent bonds bonded to 4 carbon atoms
• describe how the student should obtain crystals of zinc chloride from a solution of zinc chloride.

  heat until crystallisation point is reached

  leave solution to evaporate
• 0 5 . 2 Explain why rubidium is more reactive than potassium.

  outer shell further from nucleus

  less electrostatic attraction between the nucleus and outer electron

  so electron more easily lost
• 0 6 . 6 Explain how the alkaline solution is produced.

  sodium ions and hydroxide ions are left (in solution) (because) hydrogen ions are discharged
• Explain why aluminium is more expensive than carbon.

  more energy is needed

  because aliminium is obtained by electroylsis
• Explain why the pH of an acid depends on: • the strength of the acid • the concentration of the acid.

  the stronger an acid the greater the ionisation

  the stronger the acid the lower the ph

  the higher the concentration of an acid the more acid in same volume

  so higher the concentration of acid the lower the Ph