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Find the latest values of atomic weights of the elements based on the 2021 table with changes from the 2019 table. Compare the ranges of atomic weights for elements with multiple isotopes and see the periodic table with atomic weights to five significant figures.
- 2015 Atomic Weights
A number in parentheses indicates the uncertainty in the...
- Periodic Table
Atomic weights are quoted to five significant figures. For...
- 2015 Atomic Weights
26 Σεπ 2024 · Atomic weight, ratio of the average mass of a chemical element’s atoms to some standard. Since 1961 the standard unit of atomic mass has been one-twelfth the mass of an atom of the isotope carbon-12. Atomic weight is measured in atomic mass units (amu), also called daltons.
Interactive periodic table showing names, electrons, and oxidation states. Visualize trends, 3D orbitals, isotopes, and mix compounds. Fully descriptive writeups.
The standard atomic weight of a chemical element (symbol Ar° (E) for element "E") is the weighted arithmetic mean of the relative isotopic masses of all isotopes of that element weighted by each isotope's abundance on Earth. For example, isotope 63 Cu (Ar = 62.929) constitutes 69% of the copper on Earth, the rest being 65 Cu (Ar = 64.927), so.
Atomic Weights. Table with the current relative atomic weights (atomic weights) A r (E), based on the carbon isotope 12 C with A r (12 C) = 12 (exact). Abbreviations and symbols: see application notes below.
Interactive periodic table with up-to-date element property data collected from authoritative sources. Look up chemical element names, symbols, atomic masses and other properties, visualize trends, or even test your elements knowledge by playing a periodic table game!
Atomic weights are quoted to five significant figures. For more precise values see the table of 2017 recommended values and for the 2017 changes see IUPAC website. For elements with no stable nuclides the mass of the longest-lived isotope has been quoted in brackets.
