![periodic table with molar mass periodic table with molar mass](https://db-excel.com/wp-content/uploads/2019/09/isotopes-and-atomic-mass-worksheet-answers-7-768x994.png)
See table 1 for details of range and original paper for the atomic weight of the element from different sources.However three such elements (Th, Pa, and U) do have a characteristic terrestrial isotopic composition, and for these an atomic weight is tabulated. , indicates the mass number of the longest-lived isotope of the element. Substantial deviations in atomic weight of the element from that given in the Table can occur.
![periodic table with molar mass periodic table with molar mass](https://d3rw207pwvlq3a.cloudfront.net/attachments/000/058/500/original/image.png)
Modified isotopic compositions may be found in commercially available material because it has been subject to an undisclosed or inadvertant isotopic fractionation.
![periodic table with molar mass periodic table with molar mass](https://printablee.com/postpic/2010/12/periodic-table-with-atomic-mass-and-names_401126.jpg)
![periodic table with molar mass periodic table with molar mass](https://i.pinimg.com/736x/b9/1b/ae/b91bae4a1abde11747e01a7017b60ed9.jpg)
Value being given the tabulated value should be applicable to any normal material.