Functional Groups and pKas

Vocabulary flashcards covering common organic functional groups, their structures, and approximate pKa values from the Proton Transfer Mechanism Worksheet.

Functional group

A characteristic group of atoms/bonds that possess a predictable chemical behavior, causing any compound containing it to display similar behavior.

$pK_a$ (acid dissociation constant)

An indication of how easily a functional group will give up a proton and whether the functional group will behave as an acid or a base in a chemical reaction; lower values indicate a stronger acid that gives up a proton more easily.

Alkane

A functional group with an approximate $pK_a$ of $50$.

Alkene

A functional group with an approximate $pK_a$ of $45$.

Amine

A functional group with the general formula $H\text{---}NR_2$ and an approximate $pK_a$ of $35$.

Alkyne

A functional group with the general formula $H\text{---}C \equiv C\text{---}R$ and an approximate $pK_a$ of $25$.

Ester

A functional group with an approximate $pK_a$ of $25$.

Ketone

A functional group with an approximate $pK_a$ of $20$.

Alcohol

A functional group with the general formula $H\text{---}O\text{---}R$ and an approximate $pK_a$ of $15$.

Phenol

A functional group with an approximate $pK_a$ of $10$.

1,2-diketone

A functional group with an approximate $pK_a$ of $10$.

Thiol

A functional group with the general formula $H\text{---}S\text{---}R$ and an approximate $pK_a$ of $10$.

Ammonium

A functional group with the general formula $H\text{---}NR_3^+$ and an approximate $pK_a$ of $10$.

Carboxylic acid

A functional group with an approximate $pK_a$ of $5$.

Hydrochloric acid

An acid with an approximate $pK_a$ of $-5$.

Sulfuric acid

An acid with an approximate $pK_a$ of $-10$.