Where did the different chemical elements come from?

Soon after the Universe appeared, the first atomic nuclei were formed, resulting in the Universe being filled with 90% hydrogen nuclei (protons) and 10% helium nuclei. Besides them, there was also a tiny amount of lithium, which did not exceed 0.00001% of all nuclei, while the content of heavier nuclei was even thousands of times less. However, we now have a huge amount of heavy elements in the composition of planets and gas-dust nebulae, and the source of all these substances is stars. <img alt="" src="https://miro.medium.com/v2/resize:fit:700/1*8tmd_Vxe5uo0WKB3hFujYA.png" style="height:394px; width:700px" /> All heavy chemical elements are formed through stars, but the mechanism is different for different chemical elements. <a href="https://medium.com/@deep.space/where-did-the-different-chemical-elements-come-from-a9d8613bd60c">Website</a>