Search research articles

ABOUT JoVE

Overview Leadership Blog JoVE Help Center

AUTHORS

Publishing Process Editorial Board Scope & Policies Peer Review FAQ Submit

LIBRARIANS

Testimonials Subscriptions Access Resources Library Advisory Board FAQ

RESEARCH

JoVE Journal Methods Collections JoVE Encyclopedia of Experiments Archive

EDUCATION

JoVE Core JoVE Business JoVE Science Education JoVE Lab Manual Faculty Resource Center Faculty Site

Terms & Conditions of Use

Related Concept Videos

VSEPR Theory

VSEPR Theory

Valence shell electron-pair repulsion theory (VSEPR theory) enables us to predict the molecular structure around a central atom from an examination of the number of bonds and lone electron pairs in its Lewis structure. The VSEPR model assumes that electron pairs in the valence shell of a central atom will adopt an arrangement that minimizes repulsions between these electron pairs by maximizing the distance between them. The electrons in the valence shell of a central atom form either bonding...

The Energies of Atomic Orbitals

The Energies of Atomic Orbitals

In an atom, the negatively charged electrons are attracted to the positively charged nucleus. In a multielectron atom, electron-electron repulsions are also observed. The attractive and repulsive forces are dependent on the distance between the particles, as well as the sign and magnitude of the charges on the individual particles. When the charges on the particles are opposite, they attract each other. If both particles have the same charge, they repel each other.

The Pauli Exclusion Principle

The Pauli Exclusion Principle

The arrangement of electrons in the orbitals of an atom is called its electron configuration. We describe an electron configuration with a symbol that contains three pieces of information:

The Aufbau Principle and Hund's Rule

The Aufbau Principle and Hund's Rule

To determine the electron configuration for any particular atom, we can build the structures in the order of atomic numbers. Beginning with hydrogen, and continuing across the periods of the periodic table, we add one proton at a time to the nucleus and one electron to the proper subshell until we have described the electron configurations of all the elements. This procedure is called the aufbau principle, from the German word aufbau (“to build up”). Each added electron occupies the...

VSEPR Theory and the Effect of Lone Pairs

VSEPR Theory and the Effect of Lone Pairs

Effect of Lone Pairs of Electrons on Molecule Geometry

Electron Configurations

Electron Configurations

Electron configurations and orbital diagrams can be determined by applying the Aufbau principle (each added electron occupies the subshell of lowest energy available), Pauli exclusion principle (no two electrons can have the same set of four quantum numbers), and Hund’s rule of maximum multiplicity (whenever possible, electrons retain unpaired spins in degenerate orbitals).
The relative energies of the subshells determine the order in which atomic orbitals are filled (1s, 2s, 2p, 3s, 3p,...

You might also read

Related Articles

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

Sort by

Same author

The Iso-Inverse: A Contravariant Sparse Approximate Inverse Matrix.

The journal of physical chemistry. A·2024

Same author

How delocalized are the polyacenes?

Journal of computational chemistry·2023

Same author

Economical Models for Electron Densities.

The journal of physical chemistry. A·2023

Same author

DFT exchange: sharing perspectives on the workhorse of quantum chemistry and materials science.

Physical chemistry chemical physics : PCCP·2022

Same author

Software for the frontiers of quantum chemistry: An overview of developments in the Q-Chem 5 package.

The Journal of chemical physics·2021

Same author

Q-MP2-OS: Møller-Plesset Correlation Energy by Quadrature.

Journal of chemical theory and computation·2020

Same journal

Porphyrin Aggregation Revisited: From the Four-Orbital Gouterman Model to an Eight-Orbital Framework in Porphin H-Dimers.

The journal of physical chemistry. A·2026

Same journal

Unraveling the Electronic Origin of Selectivity in Ambimodal Transition States with Valence Bond Theory.

The journal of physical chemistry. A·2026

Same journal

Mechanism and Kinetics of the Initial Oxidative Ring-Opening of Corannulene Radicals under Combustion Conditions.

The journal of physical chemistry. A·2026

Same journal

High-Resolution Absorption Spectroscopy of ND<sub>3</sub> between 59,000 and 93,000 cm<sup>-1</sup>.

The journal of physical chemistry. A·2026

Same journal

Twisted-Driven Photoionization of Aligned Chiral Molecules: Signatures of Circular and Helical Dichroism.

The journal of physical chemistry. A·2026

Same journal

Modeling the Clustering of Fumaric/Maleic Acid with Water and Na<sup>+</sup>, Cl<sup>-</sup> Ions.

The journal of physical chemistry. A·2026

See all related articles

Search research articles

Related Experiment Video

Updated: Aug 14, 2025

Computation of Atmospheric Concentrations of Molecular Clusters from ab initio Thermochemistry

Computation of Atmospheric Concentrations of Molecular Clusters from ab initio Thermochemistry

Published on: April 8, 2020

Avoiding Negligible Shell Pairs and Quartets in Electronic Structure Calculations.

Ellena K G Black¹, Andrew T B Gilbert², Simon C McKenzie¹

¹School of Chemistry, University of Sydney, Sydney, NSW2006, Australia.

The Journal of Physical Chemistry. A

|January 17, 2023

Summary

This summary is machine-generated.

Researchers identified significant shell pairs and quartets in electronic structure calculations. The Cauchy-Schwarz bound effectively identifies nonsignificant quartets, while the Hölder bound is better for nonsignificant pairs, improving computational efficiency.

More Related Videos

Probe Type II Band Alignment in One-Dimensional Van Der Waals Heterostructures Using First-Principles Calculations

Probe Type II Band Alignment in One-Dimensional Van Der Waals Heterostructures Using First-Principles Calculations

Published on: October 12, 2019

Excitonic Hamiltonians for Calculating Optical Absorption Spectra and Optoelectronic Properties of Molecular Aggregates and Solids

Excitonic Hamiltonians for Calculating Optical Absorption Spectra and Optoelectronic Properties of Molecular Aggregates and Solids

Published on: May 27, 2020

Related Experiment Videos

Last Updated: Aug 14, 2025

Computation of Atmospheric Concentrations of Molecular Clusters from ab initio Thermochemistry

Computation of Atmospheric Concentrations of Molecular Clusters from ab initio Thermochemistry

Published on: April 8, 2020

Probe Type II Band Alignment in One-Dimensional Van Der Waals Heterostructures Using First-Principles Calculations

Probe Type II Band Alignment in One-Dimensional Van Der Waals Heterostructures Using First-Principles Calculations

Published on: October 12, 2019

Excitonic Hamiltonians for Calculating Optical Absorption Spectra and Optoelectronic Properties of Molecular Aggregates and Solids

Excitonic Hamiltonians for Calculating Optical Absorption Spectra and Optoelectronic Properties of Molecular Aggregates and Solids

Published on: May 27, 2020

Area of Science:

Computational chemistry
Quantum chemistry
Electronic structure theory

Background:

Electronic structure calculations involve complex computations of two-electron integrals.
Identifying and discarding nonsignificant integrals can significantly improve computational efficiency.
Existing methods for identifying nonsignificant integrals may not be optimal for all cases.

Purpose of the Study:

To define criteria for significant shell pairs and quartets in electronic structure calculations.
To explore and evaluate methods for identifying nonsignificant pairs and quartets.
To improve the computational efficiency of electronic structure calculations by avoiding unnecessary computations.

Main Methods:

Defining significance based on two-electron integral values exceeding a threshold.
Investigating the effectiveness of the Cauchy-Schwarz bound for quartets.
Investigating the effectiveness of the Hölder bound for pairs.

Main Results:

The Cauchy-Schwarz bound successfully identifies a majority of nonsignificant shell quartets.
The Hölder bound demonstrates slightly higher power in identifying nonsignificant shell pairs.
Both methods offer potential for computational savings in electronic structure calculations.

Conclusions:

The choice of bound impacts the efficiency of identifying nonsignificant pairs and quartets.
The Hölder bound is a more effective tool for identifying nonsignificant pairs.
Implementing these identification strategies can lead to substantial improvements in computational performance.