Intermediate Topic 513 of 1102 Acids, Bases & Electrochemistry
Lewis Acids and Bases
Lewis acids accept electron pairs and Lewis bases donate them.
Practise Acids, Bases & Electrochemistry All Acids, Bases & Electrochemistry topics
In-depth explanation of Lewis Acids and Bases
A Lewis acid is an electron pair acceptor and a Lewis base is an electron pair donor, so a Lewis reaction forms a coordinate covalent bond in which both electrons come from the base. This is the most general of the classic acid-base definitions because it does not require a proton to be involved. It covers reactions such as metal complex formation, where a metal ion accepts electron pairs from ligands like water, ammonia or chloride. It also explains catalysis by species such as aluminium chloride in Friedel-Crafts reactions. Boron trifluoride, which has an empty p orbital, is a classic Lewis acid and a central idea in coordination and organic chemistry.
Going deeper: Lewis Acids and Bases
Key ideas: A Lewis base donates an electron pair and a Lewis acid accepts one, forming a coordinate covalent bond. Typical acids: BF3, AlCl3, metal cations, CO2. Typical bases: NH3, OH-, halides, H2O. Complex formation such as Cu2+ + 4NH3 giving Cu(NH3)4 2+ is a Lewis acid-base reaction, and the product is called an adduct.
Common mistakes and connections: Mistake: thinking Lewis theory contradicts Bronsted. Every Bronsted base is a Lewis base, and H+ is simply a Lewis acid, so Lewis is the broadest theory. Another error is drawing the arrow from acid to base: curved arrows start at the lone pair. Connects to coordination chemistry and HSAB.
Visualization of Lewis Acids and Bases
Planar BF3 has an empty p orbital on boron that accepts a lone pair from a donor such as NH3, making it a classic Lewis acid. The interactive lesson shows this as a live animation or chart.
Worked example and use case
Boron trifluoride accepts a lone pair from ammonia: BF3 + NH3 -> F3B-NH3.
Frequently asked questions about Lewis Acids and Bases
What is Lewis Acids and Bases?
Lewis acids accept electron pairs and Lewis bases donate them.
Is Lewis Acids and Bases a beginner, intermediate or advanced topic?
Lewis Acids and Bases is a intermediate topic in Acids, Bases & Electrochemistry. It builds on the vocabulary of beginner topics in this area.
What should I learn before Lewis Acids and Bases?
Study these earlier topics in Acids, Bases & Electrochemistry first: Arrhenius Acids and Bases, Bronsted-Lowry Theory.
What comes after Lewis Acids and Bases?
The next topics in Acids, Bases & Electrochemistry are Conjugate Acid-Base Pairs and Amphoteric Substances.
Can I practise Lewis Acids and Bases with quizzes?
Yes. The interactive lesson includes a self-check question on Lewis Acids and Bases, and the Acids, Bases & Electrochemistry quiz draws on every topic in this area.
Where Lewis Acids and Bases fits in Acids, Bases & Electrochemistry
Lewis Acids and Bases is topic 3 of 105 in Acids, Bases & Electrochemistry.