2. OBJECTIVES
ď Define a Lewis acid and base.
ďDeduce the Lewis acid and base in a chemical reaction
3. How can one substance, such as
water, be both an acid and a base,
according to the Brønsted-Lowry
definition?
Because water can act as both a
hydrogen-ion donator and a hydrogen-ion
acceptor, it can act as both an acid and a
base according to the Brønsted-Lowry
definition.
Warm up :
4. According to Gilbert Lewis, an acid
accepts a pair of electrons a base
donates a pair of electrons during a
reaction.
⢠This definition is more general than
those offered by Brønsted and Lowry.
LEWIS ACIDS AND
BASES
5. ⢠A Lewis acid is a substance that can
accept a pair of electrons to form a
covalent bond.
⢠A Lewis base is a substance that can
donate a pair of electrons to form a
covalent bond.
LEWIS ACIDS AND
BASES
â The Lewis definitions include all the
Brønsted-Lowry acids and bases.
6. Consider the reaction of H+ and OHâ.
⢠The hydrogen ion donates itself to the
hydroxide ion.
â H+ is a Brønsted-Lowry acid, and OHâ is a
Brønsted-Lowry base.
LEWIS ACIDS AND
BASES
8. Acid-Base Definitions
Type Acid Base
Brønsted-
Lowry
H+ donor H+ acceptor
Lewis
electron-pair
acceptor
electron-pair
donor
This table compares the definitions of acids
and bases.
â˘The Lewis definition is the broadest.
â˘It extends to compounds that the Brønsted-Lowry theory does
not classify as acids and bases