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
Extended periodic table (detailed cells) the seventh period, as they are calculated to have an additional so-called g-block, containing 18 elements with partially filled "g-orbitals" in each period. An eight-period table containing this block was suggested by Glenn T. Seaborg in 1969. It is not known how many elements are physically possible, if period 8 is complete, or if there is a period 9. Chemical series information for elements past hassium (except copernicium), is hypothetical and based on periodic trends. Superheavy elements may not exist, and may not follow the order of this table even if they do. Extended periodic table (detailed cells) This is