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NNDC Wallet Cards 2023 Public domain

Nuclear data: nuclides, half-lives, decay channels and types, level spin and parity, isotopic abundances.

Publisher: National Nuclear Data Center, Brookhaven National Laboratory (U.S. Department of Energy). NNDC provides the data without any warranty of accuracy or completeness.

Data as of 15 October 2024

PubChem Periodic Table API CC0

Element properties: electron configuration, electronegativity, atomic radius, melting and boiling points, density, CPK color, oxidation states, group membership.

Publisher: National Library of Medicine (NIH, USA). PubChem collects values from many sources - the source of each value is shown on the element page in PubChem.

Retrieved on 29 June 2026

IUPAC CIAAW - Abridged Standard Atomic Weights 2024 Public domain

Standard atomic weights (CIAAW 2024 abridged values) shown on periodic table tiles and element pages. For elements without stable isotopes, the mass number of the longest-lived isotope (per NNDC data) is given in square brackets.

Publisher: Commission on Isotopic Abundances and Atomic Weights (CIAAW) of the International Union of Pure and Applied Chemistry (IUPAC). Values copied unchanged from the 2024 table.

Table version: 2024

NIST Atomic Spectra Database (ASD) © U.S. Secretary of Commerce

Ionization energies (6,019 records) and spectral lines over the full wavelength range - used to display the emission spectrum of each element.

NIST Standard Reference Database 78, © U.S. Secretary of Commerce on behalf of the United States of America. Citation: Kramida A., Ralchenko Yu., Reader J., NIST ASD Team, NIST Atomic Spectra Database, https://doi.org/10.18434/T4W30F.

Retrieved on 29 June 2026

Images of Elements CC BY 3.0

Photographs of chemical elements. Each image comes from the element page on images-of-elements.com and is used under the Creative Commons Attribution 3.0 license.

Photographs by Heinrich Pniok (images-of-elements.com). Each photo links to its source page.

Retrieved on 29 June 2026