Correct is — 6Li (7,5 %) and 7Li (92,5 %); incorrect — 6Li (4.85%) and 7Li (95.15%)! Why? Becouse standard atomic weight in first case will be 6.940037 and in second 6.967460. Please find source for second one. source for the first one is ruwiki. Surprizi (talk) 13:42, 3 May 2023 (UTC)
More information isotope, Z ...
isotope |
Z |
N |
atomic mass |
% in nature |
average |
6Li |
3 |
3 |
6.015122795(16) |
7.59 % |
0.456547 |
7Li |
3 |
4 |
7.01600455(8) |
92.41 % |
6.483489 |
Ar°(Li) |
|
|
|
100% |
6.940037 |
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If I am wrong, would you please help me to calculate standard atomic weight — 6.94.--Surprizi (talk) 14:32, 3 May 2023 (UTC)
"Lithium is an element with only two stable isotopes, 6Li and 7Li, and so there is only one stable isotope ratio involved (see Figure 1). The standard isotopic reference material for lithium,1 IRMM-016, has a measured stable isotope ratio that leads to a mole fraction for 6Li of 0.0759 (which corresponds to an isotopic abundance value of 7.59%) and a mole fraction for 7Li of 0.9241 (which corresponds to the isotopic abundance value of 92.41%). The product of each isotope’s atomic mass and its isotopic abundance, summed over both isotopes leads to a calculated value of 6.94 for the atomic weight of lithium"[1][2][3].--Surprizi (talk) 14:38, 3 May 2023 (UTC)
- In addition, incorrect ratio 4.85:95.15 is comming from the average of four numbers [0.019, 0.078] ([0.019+0.078]/2=4.85) and [0.922, 0.981] ([0.922+0.981]/2=95.15). Calculation this way is incorect, becouse [0.019, 0.078] and [0.922, 0.981] are range, not simple two and two numbers. Everithing will changed through this diapasons. In case if we had only two isotopes, then everybody will be correct. On this site on the right is link to original pdf file, where you can see illustrations and will find that Lithium are not only in two places.--Surprizi (talk) 06:04, 4 May 2023 (UTC)