Other pages in this series (5)
A4
Elements left unchanged longest
Distribution of the year of the latest revision
Takeaway
- Only 4 elements have stayed unchanged since 1969 (Cu, Rb, Sr, Te); 56 were revised in 2000 or later.
- Definition
- For each element with a standard atomic weight, the year of its most recent revision.
- Formula
- Latest revision year per element.
- Denominator
- The 84 elements with a standard atomic weight today; radioactive elements without one (Tc, Np, Rn, Ra) are left out.
- How to read it
- 4 elements have not changed since 1969 (Cu, Rb, Sr, Te). 56 were last revised in 2000 or later.
- Caveats
- Counting radioactive elements would add more “unchanged” ones; their standard atomic weights were withdrawn or never existed.
| Symbol | Name | Latest revision | Current value |
|---|---|---|---|
| Cu | copper | 1969 | 63.546(3) |
| Rb | rubidium | 1969 | 85.4678(3) |
| Sr | strontium | 1969 | 87.62(1) |
| Te | tellurium | 1969 | 127.60(3) |
Download CSV: aw_a1_elements.csv
Source: Standard atomic weights © IUPAC/CIAAW 2016–2024. Commission on Isotopic Abundances and Atomic Weights, Historical changes of standard atomic weights (compiled by J. Meija), https://www.ciaaw.org/historical-atomic-weights.htm