Could molecular substitution occur?

[Frogeyedpeas]

Suppose we lived in significantly hotter conditions that what we live in right now (or lower pressure)... could organisms composed of Tin or Lead as opposed to carbon, Bismuth/Antimony as opposed to Nitrogen, Selenium and Tellurium as opposed to oxygen and sulfur respectively, and substances such as potassium and sodium in place of hydrogen exist?

Not exactly that but can life be fully functional as long as it has the proper substitutions in place?

 

[Ryan_m_b]

There are many ideas surrounding different hypothetical biochemistries but it's not a big field of research. Could be that will change in future with developments in synthetic biology or discoveries in exobiology.