Test unit 5

• Explain how the ions are held together in solid sodium chloride:

  • The ions are held together by strong electrostatic forces of attraction between metal (Na) and non-metal (Cl) which is ionic bond
  • This give them a regular, repeating pattern.
• Explain why sodium metal is malleable:

  • Due to metallic structure, It can be drawn out into wired due to layered structure of the lattice as they can slide over each other.
• Deduce the formula of the compound that contains 2+ ions and 3- ions that has the same electro-config as ARGON.

  • Ca and P
  • Ans: Ca3P2
• Bonding of Potassium Chloride:

  • Ionic bonding
• Deduce formula of ion that has charge of 2+ with the same electron config as KRYPTON

  • Sr2+
• Explain how the ions in Sodium metals are held together:

  • Soldium metal has the electrostatic attraction between the positively ions and the delocalised electrons in the metal
• Why is graphite soft:

  • only three of the four electrons in the outer shell
  • soft and slippery-layer can easily slide over each other
  • Weak forces of attraction which is easy to break meaning less energy is needed.
• The melting point of sodium chloride is much higher than that of sodium metal. What can be deduced from this information?

  • the ionic bonding in NaCl is stronger which requires more energy to 1 break than the metallic bonding in Na
• Compare the electrical conductivity of solid sodium metal with that of solid sodium chloride. Explain your answer.

  
  

  Comparison:

  • Sodium conducts and sodium chloride does NOT conduct
  • Na conducts, NaCl only conducts when molten

  Explanation:

  • Delocalised electrons flow through the metal
  • Allow e– move
  • Ions can’t move in solid state in NaCl
• Describe the bonding in a metal.

  • positive ions attracted to delocalised electrons (or sea of or free or mobile)
• Explain why magnesium has a higher melting point than sodium.

  • Mg2+ has more protons that attract delocalised electrons more strongly
• Why do diamond and graphite both have high melting points?

  • they both have giant covalent structure which means that they are bonded by strong covalent bonds that would take alot of energy to be broken.