High School Why are only hydrogen and helium created

[david2]

in the beginning the big bang only created hydrogen and helium.

why is that?

was there just not enough time to create heavier elements or is there another reason?

thx.

 

[rootone]

A small amount of Lithium as well.
The problem after that is the next element, Beryllium, cannot be made by fusion of Lithium with Hydrogen or Helium.
(If it did happen, that would be an unstable isotope which would quickly decay back to lighter elements)
After Lithium, the next sustainable fusion reaction is fusion of 3x Helium to 1 Carbon.
This occurs in stars, which have a stable high temperature and density in the core, and it is a more lengthy process than H to He,.
Immediately after the big bang conditions were not like that, the Universe was rapidly expanding and temperature falling.
https://en.wikipedia.org/wiki/Big_Bang_nucleosynthesis

 

[david2]

thank you very much for the answer.

I will dive into the info you gave me.

cheers

 

[kimbyd]

in the beginning the big bang only created hydrogen and helium.

why is that?

was there just not enough time to create heavier elements or is there another reason?

thx.

Yes. The universe became too cool for nucleosynthesis after only about 20 minutes. It takes much longer to fuse heavier elements, as they need long chains of sequential reactions to produce. So elements heavier than helium were only produced in trace quantities.

 

[david2]

after only about 20 minutes

wow, that is very very short.