Iron peak

Iron peak — local maximum in the vicinity of Fe (V, Cr, Mn, Fe, Co and Ni) on the graph "abundances of the chemical elements".

For elements before iron nuclear fusion releases energy. For elements heavier than iron nuclear fusion consumes energy, but nuclear fission releases it. Chemical elements up to iron peak are produced in ordinary stellar nucleosynthesis. Heavier elements are produced only during supernova nucleosynthesis. For this reason we have more iron peak elements than in its neighbourhood.

Binding energy

The graph below shows the binding energy of various elements. Increasing values of binding energy can be thought of in two ways: 1) it is the energy "required" to remove a nucleon from a nucleus, and 2) it is the energy "released" when a nucleon is added to a nucleus. As can be seen, light elements such as hydrogen release large amounts of energy (a big increase in binding energy) as nucleons are added—the process of fusion. Conversely, heavy elements such as uranium release energy when nucleons are "removed"—the process of nuclear fission. Although nuclei with 58 and 62 nucleons have the very highest binding energy, fusing four nucleons to nickel–56 to produce the next element — zinc–60 — actually "requires" energy rather than releases any. Accordingly, nickel–56 is the last fusion product produced in the cores of a high-mass stars (see also Silicon burning process).

ee also

* Cosmochemical Periodic Table of the Elements in the Solar System