Who We Are
- Member Directory
  Looking for someone? Search IUPAC global network.
- Organizational Chart
  A Graph is Worth a Thousand Words.
- Strategic Plan
  Our mission, vision, values and unique place in the world.
- Divisions
  The fields of chemistry covered by IUPAC volunteers.
- Committees
  Advisory and operational bodies serving our community.
- Governance
  IUPAC Statutes, Bylaws, and Standing Orders.
- Leadership
  In office from two to eight years, the officers serve the Union as volunteers.
- Secretariat
  Meet the staff who support IUPAC and its activities.
- History
  From global chemists’ need for standardization and the vision to unite.
What We Do
- Periodic Table of Elements
  Latest release based on the work of the Commission on Isotopic Abundances and Atomic Weights.
- Top 10 Emerging Technologies
  Annual selection showcasing the value and importance of Chemistry.
- Recommendations and Reports
  Unambiguous and consistent nomenclature and terminology, evaluation of data, methods or techniques, guidelines and more.
- Nomenclature
  The expertise IUPAC is known for.
- Digital Standards
  Chemical standards for the digital workplace, e.g. InChI, ThermoML, JCAMP-DX.
- Databases
  Resources to search and retrieve output of IUPAC research activities.
- Journals
  Peer reviewed and open access publications, including PAC, CTI, CI, MS, and SDS.
- Color Books
  Authoritative resources for chemical nomenclature, terminology, and symbols.
- Awards
  Honoring scientists from early career to expert level chemists.
- JCGM
  The Joint Committee for Guides in Metrology.
- Projects
  How we do what we do and how we get the word out.
- Conferences
  Endorsement program and financial support opportunities.
Events
Projects
News

Comprehensive definition of valence as a quantity

Corresponding Author: Pavel Karen

pavel.karen@kjemi.uio.no

Provisional Recommendations Abstract:

In one of many uses of the chemical term valence, it means a quantity that characterizes the bonding situation of an atom. Historically, the definition of the valence quantity has varied across different branches of chemistry. Based on our analysis of the use of this quantity, we recommend limiting the definitions to two contexts; the noun valence as the number of two-electron bonds associated with an atom, and the adjective n-valent for the oxidation state of a metal, which cover the past 70 years.

Keywords: bond order; bond valence; Lewis formula; valence; valence electrons

> Access this form to return your feedback.

Download the full text of the Provisional Recommendation

PDF 670 KB

Comments by 30 November 2026

Project Details