The most comprehensive of all acid and base theories is Usanovich concept according to which Acid is the species
"Any specie which is capable of giving cations,combining with anions or neutralize
a base to give salt"
In other words,
"Acid is a cation ,cation donor or electron pair acceptor"
According to this concept base is,
"Base is any specie capable of giving up anions or electrons combining with cations
or neutralizing an acid to give a salt"
It is thus obvious that Usanovich concept of acids and bases includes all the previous acid-base definitions.It also includes many reactions such as Oxidation Reduction reactions.
Here are some examples
ACID + BASE = SALT
SO3 + Na2O = Na2SO4
Cl2 + 2 Na = 2NaCl
The acidic and basic nature of molecule depends upon the valence of atoms of which the molecule is composed and usually the atom of highest valence affects most the acidic and basic character of molecule.
TRENDS IN PERIODIC TABLE:
IN PERIOD:
The acidic character of of elements increases on moving from left to right in a period in the periodic table.
IN GROUP:
The basic character of elements increases on passing from top to bottom of group in the periodic table.
ADVANTAGE OF THIS CONCEPT
This concept is advantageous in classifying together all examples of acids and bases .It is the most general of all the acid base theories.
