Abundance of the chemical elements stars. Lithium, beryllium and boron are rare because although they are produced by nuclear fusion, they are then destroyed by other reactions in the stars. The elements from carbon to iron are relatively more common in the universe because of the ease of making them in supernova nucleosynthesis. Elements of higher atomic number than iron (element 26) become progressively more rare in the universe, because they increasingly absorb stellar energy in being produced. Elements with even atomic numbers are generally more common than their neighbors in the periodic table, also due to favorable energetics of formation. The abundance of elements
Element collecting auction sites such as eBay. Some commercial retailers now cater to the element collecting community, even selling large quantities in sets, since purchasing elements from large chemical companies like Sigma-Aldrich is frequently prohibited or uneconomical for individuals. There are a number of specialist element providers which retail to the public over the web, sell individual element samples in addition to full and partial element sets. Many also sell elements through auction sites, such as eBay. Established specialist providers include Nova Elements, RGB Elements, Smart Elements, Metallium, Collect the Periodic Table, Luciteria and Onyxmet. Element collecting presents many challenges: some elements,