Regarding the precision and accuracy of Atomic mass

In summary, the website of CIAAW provides a list of the 2012 atomic mass in Daltons and also mentions the atomic mass of stable isotopes with an additional number in braces. This number represents the standard uncertainty expressed in terms of the least significant digit. This is a convention used in citing sources, and while it may not be used in other sources, it is important to include it in order to avoid being faulted.
  • #1
Sebastiaan
84
0
The website of CIAAW list the 2012 atomic mass in Daltons (Atomic Mass Units) and mention the atomic mass of stable isotopes followed by an additional number between braces. For example Helium-4: 4.002 603 2541(4)
My first question is what does the number between braces mean? I assume it is some uncertainty, but how to interpreter it exactly? Secondly, why aren't these number used at many other sources which appear to use the dated 4.002 602 which originates from 1983.
 
Physics news on Phys.org
  • #2
Sebastiaan said:
Secondly, why aren't these number used at many other sources which appear to use the dated 4.002 602 which originates from 1983.
Welcome to the wonderful world of "standards/conventions." As to "Why," long as you cite your sources in excruciating detail, you cannot be faulted.
 
  • #3
Alright, I think I understand the brackets after another number means a bit better, it means the standard uncertainty expressed in terms of the least significant digit, so the (4) in 4.002 603 2541(4) means a standard uncertainty of 0.0000000004
 

1. What is the difference between precision and accuracy in atomic mass measurements?

Precision refers to the consistency of measurements, while accuracy refers to how close the measured value is to the true value. In atomic mass measurements, precision would be reflected in how closely repeated measurements of the same element's mass match each other, while accuracy would be reflected in how closely the measured value matches the accepted value for that element's mass.

2. How is atomic mass measured with precision and accuracy?

Atomic mass is typically measured using mass spectrometry, which separates and measures the masses of different isotopes of an element. This method allows for precise and accurate measurements by accounting for the mass of each isotope and their relative abundances in the sample.

3. Why is it important to have precise and accurate measurements of atomic mass?

Precise and accurate measurements of atomic mass are important for a variety of reasons. They are used in determining the chemical composition of substances, understanding the properties and behavior of elements, and in various industries such as pharmaceuticals and materials science. These measurements also contribute to our overall understanding of the fundamental building blocks of matter.

4. Can atomic mass measurements ever be 100% precise and accurate?

In theory, yes, but in practice, it is nearly impossible to achieve 100% precision and accuracy in atomic mass measurements. There are always limitations and sources of error, such as instrument sensitivity and human error, that can affect the results. However, with advancements in technology and techniques, scientists are constantly striving to improve the precision and accuracy of these measurements.

5. How do scientists ensure the precision and accuracy of atomic mass measurements?

Scientists use various methods to ensure the precision and accuracy of atomic mass measurements. These include using multiple instruments and techniques to verify results, calibrating instruments regularly, and using certified reference materials with known atomic masses for comparison. Additionally, peer review and replication of experiments play a crucial role in validating the precision and accuracy of atomic mass measurements.

Similar threads

Why wasn't fluorine used as a standard for atomic mass?
    • Chemistry
Replies
6
Views
2K
I In what cases (precisely) are Hund's rules valid?
    • Atomic and Condensed Matter
Replies
3
Views
2K
I Qs re the behavior of atoms after decoupling completed
    • Cosmology
Replies
1
Views
971
How do we know the mass of an electron?
    • Electromagnetism
Replies
28
Views
2K
I Why no plane waves of macroscopic bodies? The micro-macro threshold...
    • Quantum Interpretations and Foundations
2
Replies
41
Views
3K
Doubts regarding Atomic mass,relative atomic mass and mass number.
    • Chemistry
Replies
1
Views
3K
Chemistry - isotpic mass, atomic mass, mass number
    • Biology and Chemistry Homework Help
Replies
2
Views
4K
A Creating a new compound (involving K,Ca,H,N). Is it possible?
    • High Energy, Nuclear, Particle Physics
Replies
1
Views
631
What is the difference between atomic mass and molar mass in chemistry?
    • Chemistry
Replies
1
Views
3K
I Heisenberg Uncertainty vs Measurement Error
    • Quantum Physics
2
Replies
48
Views
4K

Hot Threads

Recent Insights

Back
Top