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Fundamentals of Acids and Bases

Terms

Fundamentals of Acids and Bases

Fundamentals of Acid-Base Chemistry

Acid  -  A substance that has the potential to donate a proton or accept an electron pair.
Acidic  -  Having a pH less than 7 or a pOH greater than 7.
Amphiprotic  -  A species that can either donate or accept a proton, e. g. water.
Amphoteric  -  A species that can either donate or accept a hydroxide ion, such as Al(OH)3. Many chemistry texts incorrectly use this term to mean that a substance can act as either an acid or a base.
Arrhenius Model  -  Arrhenius proposed that acids are substances that produce protons (H+) in aqueous solution, whereas bases produce hydroxide ions (OH-) in aqueous solution. Compare his model with the Bronsted-Lowry definition and the Lewis definition.
Base  -  A substance that can accept a proton, release OH-, or donate an electron pair.
Basic  -  Having a pH greater than 7 or a pOH less than 7.
Bronsted-Lowry Definition  -  Bronsted and Lowry define an acid as a proton (H+) donor and a base as a proton acceptor. Compare this model with the Arrhenius Model and the Lewis definition.
Conjugate Acid  -  A molecule that can be described as a base that has gained one proton.
Conjugate Base  -  A molecule that can be described as an acid that has lost one proton.
Dissociate  -  Separate into its ion constituents.
Lewis Definition  -  Lewis defined an acid as an electron pair acceptor and a base as an electron pair donor. Compare his model with the Arrhenius model and the Bronsted-Lowry definition.
Oxyacid  -  A molecule of the form AOn(OH)m, where A is a non-metal.
Pauling-Ricci rule  -  For oxyacids, the more electron withdrawing (more electropositive) the non- metal center, the stronger the acid due to a weakening of the O-H bond. This trend is approximated by the equation: PK a = 8 - 9f + 4n , where f is the formal charge on A when all oxygens are singly bound to A, and n represents the number of O atoms bound to A that are not bound to an H.
pH  -  A measure of the hydrogen ion concentration, it is equal to - log [H+], where [H+] is the concentration of protons.
pK a  -  A measure of the strength of an acid, it is equal to – log K a, where K a is the acid dissociation constant in water.
pK b  -  A measure of the strength of a base, it is equal to – log K b, where K b is the base dissociation constant in water.
pOH  -  A measure of the hydroxide ion concentration, it is equal to - log [OH-], where [OH-] is the concentration of hydroxide ions.
Strong Acid  -  An acid with a pK a less than zero. Strong acids completely dissociate in water.
Strong Base  -  A base with a pK b less than zero. Strong bases completely dissociate in water.
Weak Acid  -  An acid with a pK a greater than zero. Weak acids do not completely dissociate in water.
Weak Base  -  A base with a pK b greater than zero. Weak bases do not completely dissociate in water.

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