Question and answer

Question and answer

Revision Notes

  1. Draw a dot and cross diagram and displayed formula to show how the covalent bonds are formed in chlorine gas (Cl2 ). The proton number of chlorine is 17.
  2. Draw a dot and cross diagram and displayed formula to show how the covalent bonds are formed in the gas ammonia (NH3 ). The proton number of hydrogen is 1; the proton number of nitrogen is 7.

  3.  Draw a dot and cross diagram and displayed formula to show the double bond in an oxygen molecule (O2 ). The proton number of oxygen is 8.

  4. Draw a dot and cross diagram and displayed formula to show the covalent bonds in hydrazine (N2H4 ). The proton number of hydrogen is 1; the proton number of nitrogen is 7.

  5.  Suggest whether you expect a covalently bonded compound such as ethanol to conduct electricity. Explain your answer.


     No. There are no ions or delocalised electrons present.

  6. Explain why a covalently bonded compound such as carbon dioxide has a relatively low melting point.


    The intermolecular forces of attraction between the molecules are weak.

  7. Explain why diamonds has a very high melting point.


    Each carbon atom is strongly covalently bonded to four other atoms forming a very strong giant lattice structure. A very high temperature is needed to break down the structure.

  8. Describe how the structure of graphite is different from that of diamond.


     In graphite, each carbon atom is strongly covalently bonded to three other carbon atoms. The remaining outer shell carbon electron is delocalized and so can move along between the layers formed by the covalently bonded carbon atoms.