radiometric dating- a method of dating geological or archeological specimens by knowing the decay rate of radioactive isotopes

isotopes- atoms of the same element that differ in the number of neutrons they contain

mass number- the total number of protons and neutrons in the nucleous

radioactive decay- when unstable nuclei release particles or radiant energy until they are stable

radioactive isotopes- isotopes that undergo radioactive decay

half life- the amount of time it takes for one half of any sized sample of an isotope to decay into a stable form

this depends on the isotope
the amount of radioactive isotope can be measured to help determine the material's age
see page 283 for details

first organic compounds

amino acids may have been formed when high temperatures combined the gases ammonia, hydrogen, water vapor, and methane
complex chemical reactions from lightning and uv radiation would resultn proteins
some scientist think these have been carried to earth on debris

	Created by Finley Coleman over 4 years ago

9th grade Biology Note on chapter 14: history of life, created by Finley Coleman on 25/11/2019.