An Open e-Library for Engineering Entrance Exams in India.
Hard and soft acids and bases
  • Can anyone please explain what hard and soft acids and bases are? I have read through the text i have a number of times but i still can't get the hang of it....
  • 2 Comments sorted by
  • HSBA Theory: Its used in chemistry for explaining stability of compounds, reaction mechanisms and pathways. It assigns the terms 'hard' or 'soft', and 'acid' or 'base' to chemical species.

    'Hard' applies to species which are small, have high charge states (the charge criterion applies mainly to acids, to a lesser extent to bases), and are weakly polarizable. 'Soft' applies to species which are big, have low charge states and are strongly polarizable.


    Hard acids and hard bases tend to have:

    * small atomic/ionic radius
    * high oxidation state
    * low polarizability
    * high electronegativity
    * energy low-lying HOMO (bases) or energy high-lying LUMO (acids).[7]

    Soft acids and soft bases tend to have:

    * large atomic/ionic radius
    * low or zero oxidation state
    * high polarizability
    * low electronegativity
    * energy high-lying HOMO (bases) and energy-low lying LUMO (acids).[7]
  • nice on ranjan.. +1 for you there! ;-)

Howdy, Stranger!

It looks like you're new here. If you want to ask questions, login using your Google or Facebok IDs!

Login with Facebook Sign In with Google Sign In with OpenID Sign In with Twitter

In this Discussion

This is a beta version of the new Please provide your feedback here:

Share Me

  • Please share this topic with your friends. Click any of the icons below:
  • stumbleupon
  • Twitter
  • facebook
  • myspace
  • technorati
  • reddit
  • fark
  • email

Top Posters