The Arrhenius model of acids and bases.

There are three theories of acids and bases. These are Arrhenius,  Bronsted – Lowry, and Lewis, each named for the person (people) who developed the theory.

You can think of representing these theories in a Venn Diagram composed of 3 concentric circles.  The innermost circle is the Arrhenius theory which was the first of the three theories and explains the behavior of a special class of acids and bases.  The next larger circle, containing the Arrhenius circle, is the Bronsted-Lowry theory which is larger because it explains the behavior of a much larger class of chemicals.  Finally, the outer circle is the Lewis theory which explains the acid and base properties of all chemicals and encompasses the other two theories.

Acid-Venn-1

 

In 1886, a Swedish chemist named Svante Arrhenius proposed the idea that an acid is a chemical which releases a Hydrogen Ion when it is dissolved in water and a base is a chemical which releses an Hydroxide ion when dissolved in water.

{for an animation of how this works, see also our  post on strong and weak acids}

This is a fairly detailed video about Arrhenius acids and bases and slats. Its worth watching but be sure to take notes!

 

Next comes the Bronsted-Lowry theory