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.