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Where Did the Elements Come From? Section 4.4 Natural and Synthetic Elements • Not all elements are found on Earth – some were found in the spectra of the stars • Synthetic elements have been created by man Stars • Big bang THEORY • Explosions • Temperature only E could exist • Cooling matter produced Nuclear Reactions • Rxn involving a change in the composition of the nucleus of an atom • Centers of stars, H nuclei fused to form He • Nuclear fision takes place at extremely high temps Stars • As H is used up, the star shrinks and becomes hot • This causes He to fuse and form elements with higher atomic numbers • Fe and Ni are the largest formed by this (believed to be in Earth’s core) The Sun • When this happens in a sun sized star, it collapses and expands as a red giant • When this forms, other parts of nuclei are produced and larger elements than Fe and Ni are produced Artificial Elements • Transmutation – the process of changing one nucleus into another by radioactive disintegration or bombardment w/ other particles Transmutations • Transmutation rxns were discovered by bombarding elements with alpha particles • Cyclotron – device that shoots charged particles with E pulses at elements Synchrotron • Used to create superheavy elements • Particles in cyclotron can only reach max speed until it arrives for the next pulse too late. Synchrotron • Matches the acceleration of the particles • Accelerates fewer types of particles but reaches higher E than a cyclotron Superheavy Elements • When particles interact head on, they allow massive nuclei to interact and create superheavy elements. • SHE = element with atomic # higher than 106 Superheavy Elements • Some of these elements last only for a few seconds. • When meitnerium was created, it lasted for only 0.0034 seconds.