Learning objectives

This module is concerned with classification of molecular substances as polar or nonpolar. Examples used have

• up to four electron pair domains at the central atom.
   
• hydrogen or halogen as the outer atoms
   

• for compounds of type AB, classify as polar or nonpolar based on the electronegativities of atoms A and B 
   
• for compounds of type AX_n where X are all the same
   
  • classify the compound as polar or non-polar based on its charge-density map
     
  • identify whether the compound is polar from its ball-and-stick structure 
  
  
  • to deduce the shape and identify whether a given AX_n is polar
  
  
  • the direction of polarisation


• recognise that molecules where A is bonded to more than one type of atom are all polar and be able to identify the direction of polarisation.