[docdave78]

For the life of me, I've been having a hard time replicating how the atomic mass of Tritium ³H is calculated.  It has 2 neutrons and 1 proton and using the atomic mass calculation I get 2 (1.008665) + 1(1.007276) = 3.024606u, but the texts I've been reading provide the atomic mass as 3.016049 u.  I know I'm going to run into this multiple times with other elements and I've been driving myself crazy.  I can't solve for the 0.008557u delta.

How is the 3.016049u calculated?  What am I missing?

Thanks,
Dave

[AWK]

http://faculty.spokanefalls.edu/InetShare/AutoWebs/AsaB/Phys103/Chapters31_32Solutions.pdf

[docdave78]

AWK,

Thank you, I've seen that example floating around the internet in my searches.  The 3.016049u appears to be the mass of the intact nucleus of Tritium and is used in calculating the mass defect.  But it still doesn't answer the question of the value of 3.016049u.

How is the weight of the intact nucleus calculated?  3.016049 is not equal to 2 neutrons and 1 proton given the constants of n=1.008665u and p=1.007276u.

I understand the proton value in the mass defect calculation to be equal to the mass of a proton and its corresponding electron (1.007276 + .000549 = 1.007825)

[AWK]

Mass defect is equal to binding energy of nucleons in nucleus of tritium.