This is the situation when all the elements were formed
Abundance of primordial elements. ------------------------------------------- the Big Bang model it is possible to calculate the concentration of helium-4 , helium-3 , deuterium, and lithium-7 in the universe as ratios to the amount of ordinary hydrogen.The relative abundances depend on a single parameter, the ratio of photons to baryons. This value can be calculated independently from the detailed structure of CMB fluctuations. The ratios predicted (by mass, not by number) are about 0.25 for 4 He / H , about 10 −3 for 2 H / H , about 10 −4 for 3 He / H and about 10 −9 for 7 Li / H . The measured abundances all agree at least roughly with those predicted from a single value of the baryon-to-photon ratio. The agreement is excellent for deuterium, close but formally discrepant for 4 He , and off by a factor of two for ...