where did the elements come from? section 4.4. natural and synthetic elements not all elements are...

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.