bonding

• why does diamond have a high melting point

  its a giant covalent structure so it contains strong covalent bonds which requires a lot of thermal energy to break the bonds.
• covalent bonding


  a pair of electrons shared between two atoms
• ionic bonding


  strong electrostatic forces of attracion between oppositely charged ions
• why the melting point of silicon dioxide is higher than the melting point of sodium chloride

  the covalent bonding in silicion dioxide is stronger than the ionic bonding in sodium chloride.
• Describe a chemical test to show that a substance contains ammonium ions.

  add a few drops of sodium hydroxide (NaOH) solution to the test tube.

  Gently heat the mixture in the test tube.

  Now, hold a piece of moist red litmus paper near the mouth of the test tube.

  If ammonium ions are present in the substance

  The litmus paper will turn blue.
• Describe a chemical test to show that a substance contains chloride ions

  if you add silver nitrate to a substance and it forms a white precipitate that turns gray or black under light, then it indicates the presence of chloride ions in the substance.
• explain why graphite is soft and conducts electricity


  the structure is in layers with weak forces between the layers so they can easily slide over eachother making it soft. Each carbon atom makes three covalent bonds with one delocalised electron per bond. The electrons can move around to conduct electricity
• why does a giant ionic structure have a high melting point?

  the strong electrostatic forces of attraction between oppositely charged ions require a lot of energy to break