"Decay Synthesis" indicates those elements that exist primarily as the decay product of another element. So, since radon exists primarily as the decay product of radium, it is listed as a "Decay" element. Since Uranium and Thorium have extremely long half lives and are not primarily created through the decay of another element, they are not listed as "Decay" elements.
"Human Synthesis", also referred to as artificial synthesis, indicates that the longest-lived isotope half-life of that element is too low for any of the naturally nucleosynthesized element to remain today. Therefore, only through human synthesis can this element exist at any one time.
[xxx], the last line for each element, is the mass number of the most stable isotope.
Attributions:
Information presented in this periodic table is derived from multiple sources.
"Decay Synthesis" indicates those elements that exist primarily as the decay product of another element. So, since radon exists primarily as the decay product of radium, it is listed as a "Decay" element. Since Uranium and Thorium have extremely long half lives and are not primarily created through the decay of another element, they are not listed as "Decay" elements.
"Human Synthesis", also referred to as artificial synthesis, indicates that the longest-lived isotope half-life of that element is too low for any of the naturally nucleosynthesized element to remain today. Therefore, only through human synthesis can this element exist at any one time.
[xxx], the last line for each element, is the mass number of the most stable isotope.
Since core-collapse and Type Ia supernovae are contributing sources, fractions are calculated using “Type II” and “WDD2” yields. Ncore collapse / NIa = 4
Fraction of s-process and r-process material from stellar model calculation. Potential contributions from a “weak r-process” by neutron capture in core-collapse supernovae are ignored.
Attributions:
Information presented in this periodic table was derived from multiple sources including Jennifer Johnson's blog, and 2019 article with supplementary data published in Science.