George Chen   •   over 7 years ago

SRD 144 question about values

In 144, what do the numbers in parentheses mean?

"Atomic Symbol": "H",
"Mass Number": "1",
"Isotopic Composition": "0.999885(70)",
"Relative Atomic Mass": "1.00782503223(9)"

"Atomic Symbol": "H",
"Mass Number": "7",
"Relative Atomic Mass": "7.0527(11#)"

• 2 comments
• 

  Heather Evans Manager   •   over 7 years ago

  Hi George, Thanks for the question! The numbers in parentheses denote the uncertainty in the value. If there is #, the value and the error were derived not from purely experimental data, but at least partly from systematic trends.

  This information can also be found in the references on the data.gov page for SRD 144.

  If you have more questions, let me know!

  heather

• 

  Don Burgess   •   over 7 years ago

  Extra info on the numbers in parentheses.
  0.999885(70)
  means 0.999885 +/- 0.000070
  The uncertainty number in parenthesis is for the last digits

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