How the Chemical Elements formed
- Light Elements are formed as a result of fusion in Stars.
Stars like the Sun fuse Hydrogen nuclei (i.e Protons) into Helium and similar small nuclei including Carbon. When it becomes a Red Giant, it fuses Helium and the other small nuclei into a larger nuclei.
Nuclei larger than Iron cannot be formed by this process becuase too much Energy is needed.
- Heavy Elements are formed when a massive Star collapses then explodes as a Supernova.
The enormous force of the collapse fuses small nuclei into larger nuclei than Iron. The explosion scatters the Star into Space.
The debris from a Supernova contains all the known Elements from the lightest to the heaviest. Eventually, new Stars form as Gravity pulls the debris together.
Planets form from debris surrounding a new Star. As a result, such Planets will be composed of all the known elements too.