AtomicWeight: The Atomic Weights of Chemical Elements

AtomicWeightR Documentation

The Atomic Weights of Chemical Elements


Atomic weights of chemical elements according to the IUPAC table.




The capitalized version AtomicWeight is a data frame containing the IUPAC table of atomic weights. This data frame has following colums: Number, Name, Symbol, Weight, Footnotes.

Note that as in the IUPAC table, the Weight is given as a text rather than as numeric objects. It comprises the standard values and the uncertainties (in parentheses, following the last significant figure to which they are attributed). See IUPAC report for explanation of the Footnotes.

The lower case version atomicweight is a simplified list that only contains the weights (as numeric values) and allows symbolic computations with elements to arrive at molecular weights.


Molecular weights of chemical elements may vary due to different isotope compositions, depending on geology, industrial processes or biological activity. Please consult the IUPAC Technical report about the details. The data set contains NA for elements that have no stable isotopes (except U, Th, Pa).


Thomas Petzoldt


Wieser ME, 2006. Atomic weights of the elements 2005 (IUPAC Technical Report). Pure Appl. Chem. 78 (11), 2051–2066., 2006. DOI: 10.1351/pac200678112051

See Also

other datasets: Bathymetry, Constants, Oceans,

molweight for molecular weight calculations with molecular formulae.


## assess the data in the IUPAC table (with all footnotes)
AtomicWeight[AtomicWeight$Symbol == "C",]

## use the lower case version for simple calculations:
with(atomicweight, C)

## it can also be used to calculate molecular weights
## via symbolic computation
with(atomicweight, H * 2 + O)

marelac documentation built on Sept. 25, 2023, 5:06 p.m.