Jove
Visualize
Contact Us
JoVE
x logofacebook logolinkedin logoyoutube logo
ABOUT JoVE
OverviewLeadershipBlogJoVE Help Center
AUTHORS
Publishing ProcessEditorial BoardScope & PoliciesPeer ReviewFAQSubmit
LIBRARIANS
TestimonialsSubscriptionsAccessResourcesLibrary Advisory BoardFAQ
RESEARCH
JoVE JournalMethods CollectionsJoVE Encyclopedia of ExperimentsArchive
EDUCATION
JoVE CoreJoVE BusinessJoVE Science EducationJoVE Lab ManualFaculty Resource CenterFaculty Site
Terms & Conditions of Use
Privacy Policy
Policies

Related Concept Videos

Bronsted-Lowry Acids and Bases02:58

Bronsted-Lowry Acids and Bases

The acid-base reaction class has been studied for quite some time. In 1680, Robert Boyle reported traits of acid solutions that included their ability to dissolve many substances, to change the colors of certain natural dyes, and to lose these traits after coming in contact with alkali (base) solutions. In the eighteenth century, it was recognized that acids have a sour taste, react with limestone to liberate a gaseous substance (now known to be CO2), and interact with alkalis to form neutral...
Relative Strengths of Conjugate Acid-Base Pairs02:29

Relative Strengths of Conjugate Acid-Base Pairs

Brønsted-Lowry acid-base chemistry is the transfer of protons; thus, logic suggests a relation between the relative strengths of conjugate acid-base pairs. The strength of an acid or base is quantified in its ionization constant, Ka or Kb, which represents the extent of the acid or base ionization reaction. For the conjugate acid-base pair HA / A−, the ionization equilibrium equations and ionization constant expressions are
Acid/Base Strengths and Dissociation Constants03:02

Acid/Base Strengths and Dissociation Constants

The relative strength of an acid or base is the extent to which it ionizes when dissolved in water. If the ionization reaction is essentially complete, the acid or base is termed strong; if relatively little ionization occurs, the acid or base is weak. There are many more weak acids and bases than strong ones. The most common strong acids and bases are listed below:
Lewis Acids and Bases02:33

Lewis Acids and Bases

In 1923, G. N. Lewis proposed a generalized definition of acid-base behavior in which acids and bases are identified by their ability to accept or to donate a pair of electrons and form a coordinate covalent bond.
A coordinate covalent bond (or dative bond) occurs when one of the atoms in the bond provides both bonding electrons. For example, a coordinate covalent bond occurs when a water molecule combines with a hydrogen ion to form a hydronium ion. A coordinate covalent bond also results when...
Lewis Acids and Bases02:16

Lewis Acids and Bases

This lesson delves into Lewis acids and bases in the context of the octet rule for electron-deficient compounds. Here, the concept is discussed, emphasizing the group 13 elements like boron or aluminium. Since group 13 elements possess three valence electrons, they form trivalent compounds with a sextet of electrons and a vacant orbital for the central atom. Consequently, these electron-deficient compounds accept electrons from other species to complete their octet in a chemical reaction. They...
Ions as Acids and Bases02:54

Ions as Acids and Bases

Salts with Acidic Ions
Salts are ionic compounds composed of cations and anions, either of which may be capable of undergoing an acid or base ionization reaction with water. Aqueous salt solutions, therefore, may be acidic, basic, or neutral, depending on the relative acid-base strengths of the salt’s constituent ions. For example, dissolving the ammonium chloride in water results in its dissociation, as described by the equation:

You might also read

Related Articles

Articles linked to this work by shared authors, journal, and citation graph.

Sort by
Same author

Hard and soft acids and bases: structure and process.

The journal of physical chemistry. A·2012
Same author

Hard and soft acids and bases: atoms and atomic ions.

Inorganic chemistry·2008
See all related articles

Related Experiment Video

Updated: Jun 21, 2026

Determination of the Gas-phase Acidities of Oligopeptides
11:00

Determination of the Gas-phase Acidities of Oligopeptides

Published on: June 24, 2013

Hard and soft acids and bases: small molecules.

James L Reed1

  • 1Department of Chemistry and Center for Functional Nanoscale Materials, Clark Atlanta University, 223 Brawley Drive SW, Atlanta, Georgia 30314, USA. jreed@cau.edu

Inorganic Chemistry
|July 11, 2009
PubMed
Summary

Chemical hardness in molecules was investigated using the Hard and Soft Acids and Bases principle. Responding valence electrons, particularly those near the binding atom, determine molecular hardness.

Area of Science:

  • Quantum Chemistry
  • Theoretical Chemistry
  • Chemical Reactivity Theory

Background:

  • The Hard and Soft Acids and Bases (HSAB) principle is a cornerstone of chemical reactivity.
  • Understanding molecular hardness is crucial for predicting chemical interactions and reaction pathways.
  • Previous studies focused on atomic hardness, with less emphasis on localized molecular properties.

Purpose of the Study:

  • To determine the operational chemical hardness of second-period anionic derivatives (hydride, chloride, fluoride).
  • To identify the structural origins and processes responsible for hard-soft behavior in small molecules.
  • To investigate the localized nature of chemical hardness within molecules.

Main Methods:

  • Application of the Pearson Principle of Hard and Soft Acids and Bases.

More Related Videos

Sub-nanometer Resolution Imaging with Amplitude-modulation Atomic Force Microscopy in Liquid
10:25

Sub-nanometer Resolution Imaging with Amplitude-modulation Atomic Force Microscopy in Liquid

Published on: December 20, 2016

Unveiling Histone Proteoforms using 2D-TAU Gel Electrophoresis
07:20

Unveiling Histone Proteoforms using 2D-TAU Gel Electrophoresis

Published on: October 18, 2024

Related Experiment Videos

Last Updated: Jun 21, 2026

Determination of the Gas-phase Acidities of Oligopeptides
11:00

Determination of the Gas-phase Acidities of Oligopeptides

Published on: June 24, 2013

Sub-nanometer Resolution Imaging with Amplitude-modulation Atomic Force Microscopy in Liquid
10:25

Sub-nanometer Resolution Imaging with Amplitude-modulation Atomic Force Microscopy in Liquid

Published on: December 20, 2016

Unveiling Histone Proteoforms using 2D-TAU Gel Electrophoresis
07:20

Unveiling Histone Proteoforms using 2D-TAU Gel Electrophoresis

Published on: October 18, 2024

  • Identification of 'responding electrons' (non-transferring valence electrons) as the structural basis for hardness.
  • Utilized a modified Slater model to describe the electronic relaxation process associated with hardness.

    • Main Results:

    • Chemical hardness in the studied anionic derivatives is directly linked to their responding valence electrons.
    • A relaxation process, modeled by a modified Slater approach, governs the hard-soft behavior.
    • Demonstrated that chemical hardness is a local property, primarily influenced by electrons near the base's binding atom.

    Conclusions:

    • The study confirms that molecular hardness, like atomic hardness, originates from specific electron populations.
    • The localized nature of chemical hardness is highlighted, emphasizing the role of the binding atom's electrons.
    • Findings provide a refined understanding of the HSAB principle at the molecular level.