Why do some materials have higher melting points than others?(e.g metal & plastic?)

Question: Why do some materials have higher melting points than others?(e.g metal & plastic?)
- Keywords:
  material,
  melting point,
  temperature
Asked by maddiec to Christina, Jess on 28 Jun 2013.
- Christina Pagel answered on 28 Jun 2013:
  
  Jess will answer this better than me, but i think it’s due to the structure of the materials – structure with tighter bonds between the atoms/molecules will have a higher melting point (because it takes more energy to break those bonds and let the atoms/molecules move around more freely).

Question: Why do some materials have higher melting points than others?(e.g metal & plastic?)