Explain lewis theory of acid

\( \newcommand\) • • • • • • Acids and bases are an important part of chemistry. One of the most applicable theories is the Lewis acid/base motif that extends the definition of an acid and base beyond H + and OH - ions as described by ø The Brø nsted acid-base theory has been used throughout the history of acid and base chemistry. However, this theory is very restrictive and focuses primarily on acids and bases acting as proton donors and acceptors. Sometimes conditions arise where the theory does not necessarily fit, such as in solids and gases. In 1923, G.N. Lewis from UC Berkeley proposed an alternate theory to describe acids and bases. His theory gave a generalized explanation of acids and bases based on structure and bonding. Through the use of the Lewis definition of acids and bases, chemists are now able to predict a wider variety of acid-base reactions. Lewis' theory used electrons instead of proton transfer and specifically stated that an acid is a species that accepts an electron pair while a base donates an electron pair. Figure \(\PageIndex\)). A coordinate covalent bond is just a type of covalent bond in which one reactant gives it electron pair to another reactant. In this case the lewis base donates its electrons to the Lewis acid. When they do react this way the resulting product is called an addition compound, or more commonly an adduct. • Lewis Acid: a species that accepts an electron pair (i.e., an • Lewis Base: a species that donates an electron pair (i...

In practice, substances that are considered acids by the Lewis definition, other than those associated with hydrogen ions and protons, are specifically referred to as Lewis acids. Lewis bases include ammonia and its organic derivatives, the oxides of the alkali and alkaline earth metals, and most atoms and molecules with negative electrical charges (anions).

\( \newcommand\) • • • • • • • • • • • • • • • • • There are three major classifications of substances known as acids or bases. The Arrhenius definition states that an acid produces H + in solution and a base produces OH -. This theory was developed by Svante Arrhenius in 1883. Later, two more sophisticated and general theories were proposed. These are the Brønsted-Lowry and the Lewis definitions of acids and bases. The Lewis theory is discussed elsewhere. The Arrhenius Theory of Acids and Bases In 1884, the Swedish chemist Svante Arrhenius proposed two specific classifications of compounds; acids and bases. When dissolved in an aqueous solution, certain ions were released into the solution. An Arrhenius acid is a compound that increases the concentration of H + ions that are present when added to water. These H + ions form the 3O +) when they combine with water molecules. This process is represented in a chemical equation by adding H 2O to the reactants side. \[ HCl_\] This theory successfully describes how acids and bases react with each other to make water and salts. However, it does not explain why some substances that do not contain hydroxide ions, such as \(F^-\) and \(NO_2^-\), can make basic solutions in water. The Brønsted-Lowry definition of acids and bases addresses this problem. An Arrhenius base is a compound that increases the concentration of OH - ions that are present when added to water. The dissociation is represented by the following equation: \[ NaOH \...

Lewis Acids and Bases Lewis acids and bases are described by the Lewis theory of acid-base reactions as electron-pair acceptors and electron pair donors respectively. Therefore, a Lewis base can donate a pair of electrons to a Lewis acid to form a product containing a coordinate covalent bond. This product is also referred to as a Lewis adduct. An illustration detailing the reaction between a Lewis acid and base leading to the formation of a coordinate covalent bond between them is given below. Lewis acids and bases are named after the American chemist Gilbert Newton Lewis, who also made invaluable contributions in the fields of Table of Content • • • • • • • • Lewis Acid Lewis Acids are the chemical species which have empty orbitals and are able to accept electron pairs from Lewis bases. This term was classically used to describe chemical species with a trigonal planar structure and an empty p-orbital. An example of such a Lewis acid would be BR 3 (where R can be a halide or an organic substituent). Water and some other compounds are considered as both Lewis acids and bases since they can accept and donate electron pairs based on the reaction. Examples of Lewis Acids Some common examples of Lewis acids which can accept electron pairs include: • H + ions (or 3O +. • The cations of d block elements which display high oxidation states can act as electron pair acceptors. An example of such a cation is Fe 3+. • Cations of metals such as Mg 2+ and Li + can form coordination com...

The Lewis Definitions of Acids and Bases In 1923 G. N. Lewis suggested another way of looking at the reaction between H + and OH - ions. In the Brnsted model, the OH - ion is the active species in this reaction it accepts an H + ion to form a covalent bond. In the Lewis model, the H + ion is the active species it accepts a pair of electrons from the OH - ion to form a covalent bond. In the Lewis theory of acid-base reactions, bases donate pairs of electrons and acids accept pairs of electrons. A Lewis acid is therefore any substance, such as the H + ion, that can accept a pair of nonbonding electrons. In other words, a Lewis acid is an electron-pair acceptor. A Lewis base is any substance, such as the OH - ion, that can donate a pair of nonbonding electrons. A Lewis base is therefore an electron-pair donor. One advantage of the Lewis theory is the way it complements the model of oxidation-reduction reactions. Oxidation-reduction reactions involve a transfer of electrons from one atom to another, with a net change in the oxidation number of one or more atoms. The Lewis theory suggests that acids react with bases to share a pair of electrons, with no change in the oxidation numbers of any atoms. Many chemical reactions can be sorted into one or the other of these classes. Either electrons are transferred from one atom to another, or the atoms come together to share a pair of electrons. The principal advantage of the Lewis theory is the way it expands the number of acids and ...