ASTRON 101 Lecture Notes - Lecture 12: Protoplanet, Outgassing, Uranium-238
14 Aug 2018
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Document Summary
Radioactive decay neutron into proton or proton into a neutron. Inside atomic nucleus, weak nuclear force can spontaneously transform a. Neutron to proton - increase atomic number by 1. Proton to neutron - decease atomic number by 1. The time it takes for half of the atoms in a given sample to decay is called the. After a number n of half-lives, the fraction of original material left is fraction = material"s half-life (1/2) n. Fraction of radioactive elements vs their decay products tell us how old a rock is. The age of the rock is the time since it was last molten. The oldest rocks on earth are around 4 billion years old (some small crystals in other rocks are about 4. 3 gyr) Moon rocks up to 4. 5 gyr, and some meteorites too. Uranium 238 has a life of 4. 5 billion years that ultimately decays to lead.
