1. Definition of Acids and Bases
Arrhenius acid-base definition
-acids donate a H+ ion
-bases dissociating to form hydroxide ions
Ex: NaOH  Na+ and OH-
Ca(OH)2  Ca+2 and 2 OH-

2. Definition of Acids and Bases
Brønsted-Lowry acid–base definition
-acids donate hydrogen ions
-bases accept hydrogen ions
-acids that are formed from the nonmetals found in the second and third rows of the periodic table easily dissociate to produce hydrogen ions because these nonmetals have a large electronegativity compared with that of hydrogen.
Ex. HCl
HNO3
H2SO4
-Acids dissociate by donating hydrogen ions
Ex: HCl  H+ and Cl-
H2CO3  2 H+ and CO3-2

3. Definition of Acids and Bases
Lewis acid-base definition
-based on Lewis dot structures
-a Lewis acid is an electron pair acceptor
-a Lewis base is an electron pair donor

4. Definition of Acids and Bases
Acid-Base Strength
-Some acids and bases either dissociate or ionize almost completely, and others do so only partially
-Nearly complete dissociation is strong; partial dissociation is weak.
-The strength of an acid or a base can vary depending on such conditions as temperature and concentration.